Chapter I Vision Ahead
Chapter II The Aims of Keyline
Chapter III Soil, its Life and its Climate
Chapter IV The Keyline Scale of Permanence
Chapter V Climate--The First Factor
Chapter VI Land Shape
Chapter VII Water Supply
Chapter VIII Farm Roads
Chapter IX Trees
Chapter X Farm Buildings
Chapter XI Subdivision
Chapter XII Soil--The Eighth Factor
Chapter XIII The Keyline (Research) Foundation
Chapter XIV Unfolding the Plan
Chapter XV Completing the Landscape
Chapter XVI Fertilisers and Fertility
Chapter XVII Why Soil Conservation?
Chapter XVIII Design and Construction Of a Farm Dam
CHAPTER XIX Drains and Irrigation
CHAPTER XX The Choice of Farm Dam Designs
CHAPTER XXI Rewards of the Balanced Landscape
Addendum The Development of Narrow Tyned Plows for Keyline
The Late Percival Alfred ("P.A.") Yeomans: A Man Before His Time
By Allan Yeomans
As a young, man after abandoning a possible career in banking, he tried several fields, including the then very new, plastics industry. , mining geology , earth moving contractor
war time taxes, not on land "conservation", failed first attempt, fire killed brother-in-law
"off contour cultivation" , keyline
By Rita Yeomans
To some the work may seem a major undertaking, and consequently beyond their consideration, yet they will find it just as possible on a small scale, the pattern is the same, and in the development of a property there is pleasure and satisfaction watching the plan unfold.
Chapter I Vision Ahead
No specialist in a segment of agriculture is likely to do as much good for agriculture with his specialty as the general agricultural officer. It is this officer's duty to present the matter more practically to farmers and to ensure that each item of accumulated knowledge is seen in its proper perspective.
Chapter II The Aims of Keyline<P>
<P>The aim of the Keyline plan then is to improve all farming and grazing lands by reversing the tendency of land to deteriorate under man's occupancy
While Keyline rejects the wholly or dominantly chemical or artificial fertiliser approach of generally orthodox agriculture, it finds great value in some artificials from a new or unorthodox approach.
The plan aims generally at conserving as much water in the soil from each rainfall as the soil can use
All surplus run-off is conserved in farm dams
When water is the limiting factor, storages are designed against maximum run-offs, and not the minimum annual run-off of orthodox recommendation.
Planning not only protects land from floods, but turns flood water to advantage. Planning beats drought very easily. Planning protects land from fire.
The flood waters from prolonged heavy rains, which now go to sea within a few days, would still be in the soil and in the farm dams months later.
the increased soil moisture would be feeding ground water supplies which flow as springs to feed the creeks and rivers.
river flow would be more constant. Then the continuous but slow seepages from farm dams would be adding to these underground supplies. This water would be clean and clear, as well as constant. The present accelerated silting up of rivers would first cease and the constant flow of silt-free water would speedily regenerate them.
If six farmers or six agricultural scientists were to plan the agricultural development for the same enterprise of 1,000 acres of undeveloped land, it is certain that six different plans would emerge. They all would have differing .ideas on subdivision, house sites, trees, water conservation, soil treatment and pasture management.
if such an area was handed over to six competent Keyline farmers they would independently look at the land in the same manner, have the same appreciation of land shape and climate, the same knowledge of the value of trees in relation to land shape, and the same ideas on water. The separate plan that each would produce would be identical.
What has struck me over the last few years is the deep-rooted pessimism of most people regarding soil. Even when they examine our deep fertile soil on a hillside which they had seen previously as subsoil or even yellow shale, they. are still apt to discuss agriculture shortly afterwards in such a way as to indicate that they have not really accepted the fact that such poor material can be changed quickly into rich soil. They have seen it, they have dug their hands into it, they have accepted it on an intellectual level, but they are still bound by the dogma of orthodox agriculture.
Chapter III Soil, its Life and its Climate
SOIL is the film of life which covers much of the land surface of this planet Earth. It is so thin that a light coat of paint on a large-scale model of the earth would be much too thick to represent to scale the thickness of the soil.
Soil has a climate of its own. It is composed of the three factors, moisture, warmth, and air in combination.
[Soi] is teeming with a great variety of life forms ranging in size from the submicroscopic viruses, through bacteria, microbes, fungi, to the colossus of the various species of earthworms.
Good fertile natural soil was made or developed in a suitable climate by plants growing in the soil, by animals and birds feeding on the growth from the soil, and by the complex of soil life - Therefore, soil controlled by the farmer and grazier should rapidly increase in fertility and not deteriorate as so much soil has been doing for so long.
to increase the quantities of vegetable matter in an environment that supplies the best conditions of moisture, warmth and air for soil life, is the outstanding way to accelerate the dynamics of this life, then the landman has the basic knowledge to greatly improve and increase the fertility of his soil.
the experiments being conducted by our Commonwealth Scientific and Industrial Research Organization (CSIRO) to produce rain
fertility erosion, which is a presoil erosion - caused by a change for the worse in the soil's climate, and the villain here is man.
As the various soil-life communities feed on each other, there has to be a continuous new source of food to balance the whole ecology and biology of soil. This continuous new source of food is some form of vegetable matter.
The practices and agricultural methods that deteriorate soil climate and reduce soil fertility may take many years to produce a noticeably harmful effect on good soil, but only a few seasons to destroy the low fertility of a poor soil.
these operations in orthodox agriculture [straight line fences, roads, clearing] breaks the flow lines of water movement, causing new concentration of flow.
certain types of cultivation, notably chiselling and ripping, may increase the absorption of rain and reduce flow. [of water overland causing erosion]
It is not so essential that soil never be treated in such a way as to deteriorate its climate as it is for the farmer to understand the process he is using, and its ultimate effect, if continued, so that he can keep the general balance always in favour of his soil.
Chapter IV The Keyline Scale of Permanence
to plan the development and management of land, the many factors that are involved should be related in some logical order. The planning of one aspect cuts across others, so some must have preference.
If something is to be planned and built it needs a basis or a foundation.
A man decides to buy a tie; this decision is not as important as the decision to buy a suit of clothes. It is unlikely that he buys the suit of clothes to match the tie, but logical to buy the tie to match the suit.
Every decision should be based on adequate consideration of the whole plan of development.
I know a man who bought a dairy farm which he cursed every day. The house was at the top of a steep hill, the dairy buildings at the bottom. Maybe it is much worse to climb a steep hill after working all day than climbing a hill to work in the morning.
Man makes his moves and Nature sooner or later signifies approval or disapproval. If it is approval, man can hold it permanently, but if it's disapproval, Nature reshapes the land again in a fashion that does not suit man.
the impact of the industrial revolution on the traditional agriculture of Europe caused grave ills; in the new countries the effect was swifter, deeper, and in places disastrous. For better or for worse modern technology speeds things along enormously. It is, however, just this powerful tool of modern technology, a lever, as it were, on the fulcrum of all traditional agricultural knowledge, that can reverse the process of deterioration with equal speed.
I knew water, earth and rocks, and enough of many branches of engineering. The rest I learned by doing it. Over and beyond all this I could do what I liked, there was no one to dictate. I had the supreme advantage and the great privilege of making my own mistakes in my own way. For fifteen years my experiments, mistakes and failures have pointed the way to the solution of each approach of the work and to the completion of a workable and successful plan.
The Keyline scale of the relative permanence of things agricultural, for the planning, development and management of agricultural lands is set out in this way:
Chapter V Climate--The First Factor
Planning, then, is designed to retard moisture loss in hot weather after more moisture from rain has been induced to enter the soil's depth.
The dominantly summer rainfall region of north-eastern Australia often creates a problem of extreme water shortage in conditions where the annual rainfall is 50 and more inches.
[Tree belts will retard extreme heat and cold as well as slow drying winds]
The effect of trees on wind velocity is significant at a quarter of a mile from a good tree belt.
take complete advantage of all weather and climatic phases that will enhance soil climate
Chapter VI Land Shape
We now have a land unit with both a start and a finish. Its upper limit is the main ridge, its sides are the primary ridges and it ends at the valley or stream course below.
When land is cleared there is likely to be slower and less absorption of rain into the soil, thus causing water to concentrate quicker and flow faster in the valley.
The volume of flowing water progressively increases from the neutral line of the ridge to the valley floor.
[water flowing from neutral line to stream] In my studies of the flow patterns of water over various land surfaces I have discovered that the complete pattern, i.e., the flow pattern from the neutral line of the primary ridge to the bottom of the primary valley, always forms a flat S curve.
the one slope or saddle valley, has its keypoint at the saddle, but this keypoint is also the keypoint of another valley falling on the other side of the saddle.
Above the keyline of the valley the distances between contours in the valley are shorter than the distances between the same contours on each side of the valley, also the centre valley slope is steeper than the slopes on each side of the valley. Below, the keyline of the valley this relationship is reversed. The distances between the contours in the valley then are greater than the distances between the same contours on each side of the valley, and the slope down the valley bottom is flatter than the slopes on each side of the valley.
Water can be induced to flow where it is wanted and as it is wanted--except uphill--if our treatment and management of land is based on a full appreciation of land shapes.
if water is the critical factor by being in short supply or by unreliable rainfall, then the simple logical approach is not to waste it.
The higher the storage the more valuable is the water.
the highest cost on any of my own farm irrigation dams is below £50 per acre foot, and this cost under the circumstances stated above is sufficiently attractive to warrant the outlay to conserve all the available run-off. By comparison the lowest cost of any of our dams was £6 per acre foot, on prices and values at time of writing.
Chapter VII Water Supply
"If water is critical none should be wasted" is the Keyline aim and the guide to planning.
The picture then is of three types of dams--(1) the high series, which may be true "Keyline dams", in suitable undulating country; (2) intermediate dams, i.e., reservoirs; and (3) lower dams.
With full water control from Keyline planning, the farm environment improves, the soil improves; the pasture, crops and stock improve in health and condition and their numbers may increase many fold with the growing capacity of the property.
Now, water conservation and the use of water on farming and grazing land is essentially agricultural. Education on the matter should be controlled agriculturally. But the present water authority, namely the civil engineer, will immediately cry, "What do they know about the matter? This is a job for the engineer!"
It must be patent, too, that the engineers cannot greatly assist until agriculturalists themselves fully appreciate all that is involved and lay the whole problem before the engineer, who may then be able to advise with practical designs.
There is just no substitute for wide experience (particularly experimental or trial and error experience) and mature judgment in this specialised agricultural field of farm water control.
big dams never can control floods as effectively and cheaply as the many farm dams.
viruses or the forces in neuclei. Power and immense control comes from controlling the little things. Again, water on the rampage in a flood is uncontrollable, yet it is easy to control the smaller quantities of water where it falls as rain before its accumulation gets out of control.
Glenbawn is a moderately large dam. The total height of the wall is 251 feet, the maximum depth of water at the wall is to be 245 feet, the width of the wall is 1800 feet at the base, and the length of the wall is 2700 feet; the quantity of earth and rock in the wall is 10,000,000 cubic yards. The total cost of the dam is to be £15,000,000, and the total cost against yardage is thirty shillings per cubic yard. Again, the total water storage capacity of Glenbawn Dam is 293,000 acre feet from a catchment area of 500 square miles, equal to 320,000 acres. The dam will require a total run-off of ten and a half inches from the whole of its catchment to fill it from the empty condition.
cost of its [Glenbawn Dam] water storage capacity, which will be about £50 per acre foot
Glenbawn Dam represents an expenditure of £47 for each acre of its entire catchment area, or £47,000 for each one thousand acre farm or grazing property or forest area. This money does not improve any of the catchment area, while it renders useless some of the best land in the vicinity by covering it with water. The catchment area has to be improved in other ways with more money if Glenbawn Dam is to be protected from siltation from its deteriorated catchment.
The irrigationist wants all the water held. The flood-threatened want the dam kept empty.
Water conservation costs in Glenbawn are £50 per acre foot. The cost of the conservation capacity on the farms in a catchment area of Glenbawn's size would be less than half of this cost
My costs of water conservation capacity on our farms range from £6 to under £50 per acre foot
There is also another great storage capacity available on the farming and grazing properties of such a five-hundred-square-mile area. A Keyline soil development programme would increase the general capacity of the soil to absorb at least two inches of additional rainfall, thus providing the lowest cost storage of all.
The money required for the project under this approach would not be spent with little return, but would produce directly a quick and certain return. If advanced to the farmers and graziers it would be repaid quickly and be available for further work. There is big profit to be made from water control in agriculture.
if £15,000,000, as spent on Glenbawn, was made available as loan money to the farmers and graziers for the development of their properties in the Hunter Valley, not only would the present shocking waste of water cease, but a lot of other wonderful changes would follow.
Another interesting cost comparison is that the cost of Glenbawn on a yardage of earth in the wall basis is at least eighteen times greater than my own recent costs of earth moving for farm dams.
The ratio of earth moved to water storage capacity in Glenbawn is in the order of one cubic yard of earth to forty-two cubic yards of water. The best ratio of any of my farm dams is one cubic yard of earth moved for a capacity of sixteen cubic yards of water. A more usual ratio for farm irrigation dams is one to five or six. The higher the ratio, other things being equal, the lower the water storage cost. So, while Glenbawn's earth-water ratio is perhaps eight times more favourable than many of the farm dams of Keyline, the earth-moving cost is eighteen times higher, and, as is seen, provides a heavy balance in favour of agriculture and for keeping the flood rain where it falls.
Forests, when managed for the express purpose of disposing of excess water, can constitute the greatest absorption capacity of any type of land, and may also provide profitable use of the surplus water later in the trees themselves as a timber crop.
The glowing success stories in words and pictures of some Government irrigation areas are not confirmed in the profit and loss account of the project, since the costs of irrigation are not directly assessed against the irrigated land. The capital costs, if disclosed against each acre of irrigated land, would be found in some instances to be so high that only the toll of tax on all the people of a State allow the schemes to exist at all. However, my quarrel is not with the concept of the big dam as such but with the viewpoint that fails to realise or even consider the comprehensive nature of, and the very wide national effect to be secured from, the many farm dam and irrigation projects.
At present we are in a position of serious lack of public thought as to what is correct in methods of water conservation. We must get our thinking right first, otherwise we are likely to impose a dreadful legacy in the form of continually wasting lands upon a beggared posterity. Education of public opinion on the basic importance of agricultural land as the foundation of the nation's very existence should begin in the schools.
There just must be a new approach to water. Can't we forget about the site for the giant dam on the river for a while and take a look at water where it falls, since it is here our greatest source of wealth originates?
Expert advice says that a farm dam for irrigation should be planned against the minimum annual run-off of its catchment, so that the dam is sure to be filled each year. The water supply is therefore said to be reliable, but at the time of writing there has been no run-off for over eighteen months in nearly all the areas where this advice is given.
This structure is built usually in the valleys of the farm first--anywhere--and it frequently has land below it which could be cheaply irrigated were there an outlet. But is has no large outlet to enable water to flow from it and do at least part of its own distribution. - the water has to be pumped up from the dam i Invariably, such water is used for spray irrigation
From my experience, I feel confident that the designs of the dams presented in this book will completely satisfy the requirements of the farmer and grazier, and that the construction methods and the various techniques for the use of the water will be so economical and profitable for the farmer that the ultimate aim of not wasting any water can logically be instituted as the best possible investment policy a farmer may make.
With Keyline planning and design the farmer and grazier will find that he can conserve just about all the water that would now run to waste from his property. He will certainly carry more stock and he will need more watering points and paddocks. If he has not yet, he will soon realise that farming is big business. The capital value of all farms can be increased
Water from any big scheme has to be transported great distances, which costs both large sums of money and big water losses in channel seepage and by evaporation, but from the farm dam the transport of the water is necessary for the shortest of distances, often only a few feet
risk of collapse, especially in war time, but with the innumerable small storages spread over the whole country there is presented no major risk.
finance. In the big project there is never any expectation that the big outlay will ever be returned quickly - [farm] dam is constructed quickly in a few days or a week or two, the dam is successful, irrigation is profitable, and the capital cost of the work, be it loan money or farmer's capital, is paid back in a very short time.
The big dam for irrigation and the farm size project for irrigation are both necessary for the realistic development of this country, but one aspect of this development, the farm project, has been grossly neglected.
Chapter VIII Farm Roads
Increasing volumes of flow water are hazards to roads
centre of main ridges, which form part of the boundaries of the secondary valleys, are neutral lines of no flow, and being high and dry are very suitable sites for main roads.
roads which run across the land follow the water conservation drain either above or below it; others which follow the irrigation drain are located above it so that irrigation water will not flow across the road. Again, other roads may follow the lower boundary of an irrigation area and another road on either side of the breaks of the land, namely the watercourses.
Farm roads, while serving their purpose, change the natural drainage pattern either towards destruction or preservation of land profiles. From the general planning of Keyline it will be seen that the position or sites of farm roads become natural, obvious, and constructive.
Chapter IX Trees
tree belts, where located in respect to land shape, are of tremendous benefit to land and have no disadvantages to the development and maintenance of a highly fertile soil in a stable and permanent landscape
in no circumstances is the complete clearing of a property necessary or justified
notably best pasture in a dry winter growing near the tree lines.
stock is assisted by adequate shade in the summer
retarding the drying effect of hot winds and ameliorating cold windy days.
Tree belts, since they are cooler in hot summers and warmer in winter, help to maintain the constitution of farm animals.
In wet weather the better conditions in the tree belt encourage stock to stay on pasture only a sufficient time to feed, thus keeping them for long periods in the tree belts and off the pasture, and preventing trampling damage caused by stock roaming on wet soil.
trees will be necessary for their continuous turnover of the deeper elements of fertility. They may draw these from great depths in the earth and shower them back on to the surface as leaf fall.
Steep country is not left in full timber but partially cleared to plan with timber strips left to serve as wind protection for the property. [especially if fire hazard]
The Keyline is again the planning guide for clearing. The first timber strip twenty to thirty yards wide is left immediately above or below the Keyline and forms a Keyline timber strip--our basis for planning in clearing operations. [more strips left on contour up and down the land]
important guide for determining this vertical interval between timber strips is related to the height of the trees. If trees are forty feet high and the vertical height occupied by the land in the width of the tree belt is ten feet, the timber strips would be vertically fifty feet apart.
locates the timber strips closer together in the steep country and farther apart as the country flattens. Even in very flat country of low scrub or mallee only ten to fifteen feet high, a similar formula for clearing will provide greatly improved farm conditions.
The only way to ensure perpetual timber is by providing conditions that allow trees of all ages to grow together. If each paddock in turn is closed to stock and cropped for three or more years, young trees develop in the timber strips and permanency of timber belts is assured.
The preparatory cultivation takes place some months prior to the time for planting the young trees so as to collect, in the drier conditions, as much deep moisture into the earth as possible.
A delay in planting for a year while the soil improves from a cultivation after each rain will be quickly offset by the faster growth of the trees.
allow a timber strip to develop of its own accord.
Chapter X Farm Buildings
The selection of sites for the permanent farm buildings may influence the pattern of clearing trees adjacent to the site; therefore the sites should be fixed early during the planned clearing of the land.
Permanent farm buildings should be located in respect to climatic features and land shape so that the best living and working conditions are provided on the site. Consideration is also given in the planning to the general water conservation scheme
access road must be trafficable in all weathers
The Keyline planning of the land opens up and often creates beautiful vistas
[direct access to main] work area should be of sufficient size at least to enable any vehicle working on the farm or one likely to carry goods to the farm, to turn and manoeuvre satisfactorily.
Prevailing winds in relation to smell and dust are considered.
Sufficient small paddocks are associated with the building area [for sick animals etc]
[fireproof] Improvement of land could logically start at the steps of the homestead and the first irrigation area to be developed could be the one closest to the buildings. There is no better fire break than paddocks which can be irrigated at the turn of the large water control valve on a dam.
Chapter XI Subdivision
The main subdivisions on a farming property are usually closely associated with the roads. The roads in most instances take precedence over the fence line
two main divisions: (1) All land that may be travelled by the farm tractor, or, in other words, land that can be developed mechanically by farm equipment. (2) Land that is too steep or too rocky for any farm equipment. A fence line can divide these two types of country in any large natural land division.
irrigation paddocks, large or small, may be fenced off as island paddocks which take their shape and form only from the line of the irrigation drain and the land strip below it which is to be irrigated.
With the land fenced off into its natural larger divisions, with island paddocks within these boundaries as irrigation areas, subdivision for smaller paddocks would quite logically be enclosed by fences running from the irrigation area straight up hill to the high boundary or straight down hill to the lower fence.
the better the development and improvement of a property the greater will be the number of stock watering points necessary
All subdivision paddocks should be located with the continuous possibility in mind of their further subdivision. The higher the fertility and productiveness of a property, the greater the number of paddocks that will be required to take the greatest advantage from increasing productiveness.
Chapter XII Soil--The Eighth Factor
[soil is considered last because it can be converted to high fertility soil in very short time.]
[special considerations for a specialized soil requirement]
The permanence of stock breeds and their continuous breed improvement depend firstly on the pastures and crops which in turn depend always on the soil.
No other property will be like it because all land shapes, while following as it were natural rules and patterns, are different just as are finger prints; no two are alike, they are all individual.
first gaining a complete appreciation of the overall plan as it applies to the property
water relationship - affects all the work, both as to the short-term aspects of day-to-day working and to the long-term benefit [of the farm]
full, if gradual, development.
First, a property is thought not suitable for Keyline, and then when the lines are marked in and the work starts the same folk see just the opposite--it is then the "ideal".
Generally the more critical the climate agriculturally the greater is the need for planning and the wider is the improvement that good planning will bring.
Chapter XIII The Keyline (Research) Foundation
principally in the grazing of beef cattle and sheep.
the most money consuming aspect of the whole work was that of education.
Sir Stanton, after two earlier short visits, spent ten days on "Nevallan" studying and investigating every aspect of my work. An agricultural scientist who had been engaged for many years in the academic teaching of agriculture, and who is now continuously occupied with the broad advisory field to farmers and graziers, said, "Yeomans has discovered in the Keyline concept itself something of great importance that has somehow eluded scientists all these years." The distinguished chief of a national research organisation said to me after a world trip, "Keyline in Australia is the most interesting development in world agriculture".
We needed more experiment and demonstration farms. Nothing is more convincing than the accomplished fact.
Experimental farms are never expected to pay. Our farms must do so, because that is the meaning of development.
insurance of farm dams
[visitors would often focus on what they were interested in instead of seeing the Keyline as a whole. A soil scientist may overlook the value of shelterbelts.]
Chapter XIV Unfolding the Plan
a dam with a depth of 24 feet of water at the lockpipe has generally been found to be double the cost of a dam on the same site but having a depth of 20 feet
The more water the farmer conserves the more water moves underground as seepage from his soil and from his dams. More water will also evaporate over his land.
I have suggested that dams for farm irrigation be limited to those with a capacity of a minimum of 2-1/2 million gallons, or ten acre feet.
A valley floor slope of one in twelve is too steep a site generally for a dam unless the rest of the valleys are similar or steeper. One in twenty is a satisfactory slope and one in thirty or flatter is considered good for a true keyline dam site.
[bunyip can find the slope of the valley]
The length of a dam is the distance from the water line at the middle of the wall up the valley to the top water line of the dam near the keypoint. If the length of the proposed wall (a line across the water level contour) and the length of the dam are equal, then the site satisfies what I consider minimum requirements. But if the wall length is longer than the length of the dam, then the site is rejected for water storage.
The water surface area of the proposed dam can be calculated by taking two-thirds of the area found by multiplying the length of the water line at the wall and the length of the dam measured at right angles to the wall
assume that the average depth is nought point four (0.4) times the water depth [at the lockpipe]
a width of twenty-five (30 is better) yards of trees in approximately these conditions [tree belts] appears to promote good conditions for timber-tree life and growth
The keyline tree strip works satisfactorily whether it is above or below the keyline drain. I prefer it above, so that in crossing the valley it does so above the dam, and thereby protects the dam from wind which causes wave erosion and the trees also retard evaporation; but the tree strip of an irrigation drain is located always above the drain, so that water does not flow through the trees when irrigating the paddock.
[roads] preferred site is down the neutral line of a suitable primary ridge
The most suitable minimum vertical height is estimated from the general approach that the tops of the highest trees of the lower tree strip, in this case the keyline strip, should be approximately on the same level as the ground at the lower side of the timber strip next above.
The keyline, the actual line itself which forms the water conservation drain, needs to be ten feet clear of the tree belt above it so that equipment can build the drain without obstruction from trees; the tree belt is twenty-five yards (seventy-five feet) wide and the distance therefore is eighty-five feet minimum from the keyline to the higher edge of the timber belt just above it. The grade of the land--assumed one in eight--places the top edge of the keyline tree belt ten feet six inches vertically above the keyline and which, added to the height of the trees--forty feet--gives a vertical interval of fifty feet six inches,.
generally accepted relevant figure is that such a tree belt will appreciably retard wind velocity for a distance of 1,200 feet on the windward side of the tree-belt windbreak
A tree belt or windbreak also retards the velocity of wind on the leeward side of the windbreak for a distance of approximately 200 feet under these conditions, and so provides greatly increased effect in the area approaching a second tree belt where the protection afforded from the lower tree belt would be petering out.
Where water can be conserved and flowed on to hill country, such land will become the highest valued pasture and crop land, not excluding river flats. I realise that to most people such a statement will require a lot of proof. [keyline extends irrigation to hilly land types]
(1) A keyline tree belt with cleared land above and below it. (2) A tree belt in the areas above the keyline trees with cleared land above it to the top of the watershed or main ridge. (3) A tree belt along the main road on the watershed divide or main ridge. (4) A tree belt along the upper side of the irrigation drain with rain-only pasture or crop land above it and irrigation land below. (5) A tree strip along the lower boundary of the irrigation area with the irrigation country above it and rain-only land below it to and including the bottom of the secondary valley.
each primary unit is designed individually
Other than the tree strip which crosses a valley when continued to plan, all trees should be cleared from both primary and secondary valley bottoms.
There are many who recommend the leaving or planting of trees along a broken stream course or an erosion gully in the bottom of a primary or secondary valley to protect the land from soil erosion. In the great majority of cases in our climate and soil conditions, all that the trees "protect" is the permanence of the gully. They will prevent the easy smoothing over of the break when smoothing may be warranted.
Chapter XV Completing the Landscape
[if you burn, focus on the hard to burn large pieces first; use the small pieces to burn the large pieces]
soil is improved far beyond its best natural state
The time that is required to improve and consolidate the improved soil climate is generally three years. The soil and with it the pasture will continue to improve for some, as yet, indefinite period of time beyond the three years with no further treatment beyond reasonably good management practices.
Keyline cultivation at the end of the first year is designed to promote the best association of moisture, warmth and air in the soil to the full depth of the pasture rooting system so that a rapid climax development of the beneficial soil life takes place. All of the available vegetable matter including the valuable dead pasture root mass is quickly incorporated into the soil and so forms part of the soil itself.
If the first-year keyline cultivation is affected by drought conditions preceding and following the work, there will be little, if any, apparent improvement in the soil, and pasture will be temporarily reduced.
The benefit would then be obtained later in the rapid response of both the soil, in the improvement of its fertility, and the pasture when moisture and warmth are again present. This condition was experienced in 1957 on our new properties. Where the second or third of the three yearly keyline cultivations were done there was a very noticeably lessened loss of pasture, the worst results being only on the first keyline cultivation--the one-year-old soil--and in 1956 the soil condition, at the time set for the keyline cultivation of some areas, was very wet, and in the new areas, soil asphyxiation was evident. It would probably have been better to cancel the keyline cultivation for all the areas but as our work is continuously experimental, the cultivation proceeded. Rain persisted and kept all the soil overwet right through to and past the middle of winter. Under these conditions, air which is so obviously essential, is excluded by excess water. The desirable balance of moisture, warmth and air in the soil had been destroyed.
[by working around existing timber, leaving it in the form of belts, you can get a 40-year-old looking property in 2-3 years.]
Chapter XVI Fertilisers and Fertility
The two landscape pictures, the one that is all good and the other that is nearly all bad, may have started together on similar land and during the first decade or two may have remained very much alike. The factors that influenced them in the improvement of the one and the deterioration toward complete destruction of the other may have been very small or slight. Yet in the one case these factors produced a change in the balance of things which caused a movement in the downhill direction of ruin, while in the other the changed conditions of the environment resulted in an improvement.
the matters of greatest importance in the change and improvement of soil are those factors of soil life which are very responsive to the improvement or otherwise of soil climate.
The older use of the various lime products had set a pattern, which in varying degrees was followed in the use of superphosphate. Later the failure of superphosphate to produce, on some land, its early success stories was found to be due to another factor which, when provided for, extended again the use of superphosphates on the pasture lands. The addition of lime with superphosphate to neutralise its acidity, which had prevented the early establishment of clover species on some lands, was a notable advance.
On complete and fertile soils neither superphosphate nor any other chemical fertiliser could show results.
lack of response to chemical treatment was said to indicate an absence of another and new mineral element or chemical, and so "trace elements" came into agriculture. While the quantity of the applications of superphosphate, which had so often produced amazing results, were extremely low, with as little as a mere hundredweight to the acre compared with 1000 tons of soil in only the top six inches of each acre, these new chemicals produced their also amazing results with minute applications of a few pounds down to an ounce to each acre of land.
Always these new advances, which were the results of the discoveries of farmers, agricultural officers and soil scientists, were paralleled by advances in bigger, faster and better mechanical equipment with which to use and apply the new knowledge to the land, and thus the development of new country became almost an accelerating process.
There is no doubt in my mind that the increased prices of wool following the second world war and the conversion of much badly erosion-damaged [after too much super-phosphate] wheat land to sheep pasture, and coupled with a succession of better rainfall seasons, has done more to check the accelerated rate of soil erosion than has the combined efforts of all Soil Conservation Departments.
there was a notable and continuing drop in the quality and food value of the wheat.
[NSW] Here again we find a general but less noticeable deterioration of the soil, which in its damaged condition still does not show a worthwhile result from superphosphates. Therefore, the lack of response is not a true indication of fertility on these north-western soils.
From this brief glance at soil in relation to the use or otherwise of superphosphate, there is no evidence that superphosphate has any material effect either way in destroying or maintaining soil structure or causing or mitigating soil erosion. The evidence suggests that the effect of superphosphate is governed solely by the condition of the natural phosphate in the soil.
One of my men in the course of his duties visited a client who had been notably successful in growing wheat by using cultivation procedures suggested by us with his Graham plow. Standing on the verandah of the farmer's home, they were looking over two adjoining paddocks which had recently been plowed in preparation for wheat crops. One paddock, the neighbour's, had been cultivated with a disk plow which had produced the fine seed bed thought necessary, and the other, the farmer's, had been cultivated with the Graham to our recommended depth, which, in this case, was about one inch deeper than the disk-cultivated land of the neighbour's adjoining paddock. Suddenly the farmer said, "Watch this". The "this" was a whirlwind, or willy-willy, in Queensland parlance, where the incident occurred, which entered the neighbour's paddock, whirling a dark thick column of his fine seed bed high into the sky. As they watched, it increased in size and blackness and moved across the neighbour's paddock and entered our farmer's paddock. Immediately it ceased to pick up dust so that the lower part of the column was practically clean air with only pieces of dry grass or stubble whirling about. These pieces indicated that the willy-willy was still twisting at its full speed, probably upwards of 50 miles per hour. All was soon over and an immediate examination of our farmer's paddock, initially left somewhat rough and cloddy, showed it contained considerable quantities of very fine soil particles or dust with the clods. The fact that the dust (or fine clay particles) did not rise indicates that the effective wind velocity of the willy-willy at the fine dust zone had been reduced by the special cultivation to less than ten miles per hour.
Now the fact that our farmer friend did not lose any soil under his method of cultivation and the neighbour did from his fine seed bed is not the really significant point to the story What appears to me to be so very important is the fact that a method of cultivation reduced wind velocity very drastically; wind which, on other occasions, may continue for days to draw critical quantities of moisture out of the soil and to its great detriment.
[creating a fine silt with a disk plow can lead to compacted soil below the plow (aka plow-sole). This inhibits moisture/air exchange, a Graham plow can chisel into the new compacted layer, greatly increasing moisture holding capacity]
[if keyline type cultivation can produce such beneficial results, does that not call into question element, trace elements, and chemical fertilizers?]
Agricultural practices should be designed to accelerate nature's beneficial processes.
What, for instance, was the weight of phosphate, including the plant available and unavailable types, that was carried to sea in a period of five weeks when six major floods occurred in the Hawkesbury River of New South Wales. As I saw it then, the floods were not water, but soup, its ingredients the finest and most valuable constituents of soil. At the same time other rivers were likewise transporting to the ocean not only phosphates but every other valuable soil element.
would the trace element be abandoned as a method of soil improvement? The answer to this question is simply no, and the reason is a direct one concerning time and money. The results from trace elements are very rapid, and they would almost always have the great advantage of promoting quicker initial growth, when compared with root organic accumulation, the main basis of the high development of soil in Keyline.
the period that must elapse before any effect is strongly evident is from twelve to fifteen months, but our experiments do not yet cover a sufficiently wide field for me to be sure whether this time is relatively constant or otherwise.
In climatic conditions similar to those on my own farms this time factor appears to be relatively constant, but reports on these matters from dryer areas are conflicting, some suggesting the apparent release of a trace element within a few months of the first rain on the new cultivation, and others, that two years or a little more brings the desirable release. No doubt the actual chemical association of the element is a factor also with climate and weather conditions. The very important effect though to the landman who is developing a pasture and strictly following a Keyline programme, is that the application of the trace element saves valuable time, and therefore should be used as a "trigger" element to quickly get a stronger fertility cycle under way. With the new soil programme I am now advocating it is my belief that it is generally unlikely that there will ever be any need for a second application of trace elements.
As with the trace elements, it seems likely that the major elements are generally present in those soils also which show the best responses to their use. But on these soils the elements are again in an unavailable condition as far as plants are concerned, or alternatively, the rate at which they naturally become available is too slow.
Now the chemical school could show wonderful results which never lost in the before and after pictures with which they continuously supported their claims. Furthermore, because chemical fertilisers are very big business, and big business, very sensibly, always allocates appropriate moneys for special advertising and public relations generally, the chemicals had the advantages of the big money. On the other hand, there is little or no money to be made in the advocacy of the organics in farming. When organic fertilisers such as composts and farmyard manure were claimed, and more often than not, in my opinion, proved to be superior and in fact something more than superior in that they were right, logical and natural, it became a simple matter for the chemical adherent to analyse the organic fertilisers and show that on the chemical analysis they offered less in value of the basic chemical known to be plant foods than did the artificial fertilisers. Then the organic school believed in the "cycle of life" and that everything that came from the soil should be returned to the soil to complete the cycle and continuously improve the soil. The adherents of the chemicals then could show that in the modern world, with its various waste disposals, including water-borne sewage, the cycle of complete return was impossible in a general way, even if possible in some instances by concentrating the waste of other lands on to the organics farms. Therefore, they argued that the chemicals taken by the plant and animals from the land must still be returned by artificial fertilisers. It is my view that eventually all agricultural land should be capable of supporting its own fertility without the additions of outside chemical fertilisers or organic materials other than those produced by the land itself
It is my firm conviction that any system of farming and grazing which will create conditions in soil which increase its organic life is creating simultaneously a sound and sure basis for healthy pastures and crops.
I have decided in my own case to assume that any chemical not a natural ingredient of soil should be considered as probably very harmful to soil and the general health of all life which comes from the soil.
all artificial fertilisers do not have the same degree of harmful effects.
sulphate of ammonia quickly affects the earthworm population
This last experiment was conducted on my own property, where two similar-sized paddocks were treated identically as to keyline cultivation and stocking control, except that one paddock had an initial dressing of one hundredweight of superphosphate while the other had three hundredweights applied each year. The stock reactions were watched, but there was none until after the end of the third year, when it was found that the cattle concentrated unduly on the one hundredweight paddock. The two paddocks adjoined and with the common gate left open for free movement the stock at this time very definitely favoured the one hundredweight paddock. After the third year they were often driven back into the heavy -superphosphate dressed paddock but would not eat it down, so that the one paddock was nearly bare while the second carried plenty of grass which the stock refused. At the same time there were then fewer earthworms in evidence in the second paddock. In 1956 number one paddock yielded a good crop of mushrooms and number two, with the heavy application of superphosphate, had no mushrooms.
On the other hand, an experiment to improve soil and develop pasture without the use of superphosphate or any other fertiliser as compared with the initial use of one hundredweight of the superphosphate showed two things very clearly. One, that my own soil can be developed by Keyline methods without superphosphate, and two, that then it takes longer.
in good seasons soil development in Keyline proceeds very satisfactorily with a one hundredweight initial application, but if the season is dry and no climax development takes place in the soil after the first application, then a second application is an appreciable advantage. Many other experiments of our own tend to confirm the belief that superphosphate is much more valuable when used in Keyline methods to directly improve the soil by providing the initial "kick" for the rapid development of the pasture root system, which then is the real basis for soil and pasture development, than it is when used simply to stimulate pasture growth.
[landmen with 30 years using super phosphate] Each of them told me that he was considered a crank by other farmers when he started the use of superphosphate to develop improved pasture, but, on the other hand, was considered a progressive farmer by soil scientists and, of course, by himself. They all applied superphosphate generally each year and saw their poor pasture develop a higher and higher carrying capacity. The top dressing, with various added pasture seeds, was spread by similar means by each of them. Then, after some years, the period varied with each farmer, something went wrong. With some the higher carrying capacity was followed by higher and higher lamb mortality rates, more disease, and, as one put it, queer behaviours in the flock. There was more need to be a progressive farmer to keep up with the newest cures for the newest diseases and troubles. Pastures that had been their pride and pleasure later collapsed and some of the farmers faced disaster. Great efforts were made to determine the cause of the troubles with every help being given from the various sciences of agriculture. There was a consistent pattern to the various accounts, although the causes and cures were not the same. The pasture which was developed with the aid of the superphosphates had gradually become shallower rooted, and so the plant nutrients other than the applied phosphate, were progressively extracted from a very shallow horizon of the soil. Eventually one or other of these elements was gone, and the collapse of the pasture resulted.
the application of the missing element some sort of recovery took place, and each was able to carry on again, some with the help of bank finance. But while the pasture recovered, the health of stock and survival rates were not good. Often the pasture was plowed up in some paddocks and a crop grown. On this land the following pasture was better, with notably less health troubles.
It seemed to me that the length of time their pasture lasted in apparently flourishing conditions was very closely related to their climate. The better the climate the longer the period before the collapse. One farmer opined that the continuous dressing of superphosphate had made the pasture lazy. It simply took the line of least resistance and grew only shallow roots in the very surface of the soil where the superphosphate was applied.
Another compared his pasture failure to feeding a jackass (Kookaburra) at the doorstep. Eventually, so he said, the bird becomes completely dependent and if not given the food he needs he forgets to hunt his own and will be found dead on the doorstep if the householder is away for any length of time. The pasture roots, when the deficiency becomes critical, cannot go down into the soil below, which has probably become dead because roots and the full soil life do not live there.
I had the rather wonderful experience of visiting, with two of my own men, an area of pasture which had received a yearly application of three to four hundredweights of superphosphate per acre for thirty years, and, we were told, never been dry or even short of water. It was irrigated land. Under such circumstances it is difficult not to ask pointed questions which often, by the mere perversity of human nature, are countered in a manner to disguise the real truths which one wants to know. However, I signalled my men, whom I could see were anxious to ask the questions, to wait for the story to unfold itself; and a very interesting and informative story it was.
On this area carrying capacity ranged from nine sheep per acre in the winter to thirty-three per acre in the summer, with an average of seventeen sheep to the acre all the year round. Immediately lambs were born on the pasture both the lambs and their ewes were moved to dry, undeveloped, unirrigated land, where they remained to rear them. Older sheep were then placed in the pasture paddock. But no lamb could be raised on this wonderful irrigated pasture; it seemed that they just died. Other sheep could not be kept too long on the pasture because they did not do well. No lamb had ever been born and survived to a ewe born on the irrigated pasture paddock.
In other words, this pasture was not capable of breeding anything. It was manifestly well supplied with some of the growth factors, but what about the others? Would this pasture affect hereditary factors in the sheep that were fed there for a time after they were raised to a suitable age on the completely undeveloped land?
We asked to be permitted to examine the soil of the pasture area with a spade. This was readily assented to but caused a surprise. We dug down into the soil for perhaps a foot, disclosing a near perfect moisture condition to this depth. The bulk of the pasture roots were confined to the top two inches of soil, but there was more root growth, although little enough, below this depth than I have ever found in a heavily superphosphate-dressed pasture without irrigation. The continuous but slow movement of water through the clayey soil probably carried superphosphate with it, encouraging a few roots of cocksfoot to go down. The soil itself in the top inches had a pleasant smell, but below the top there was no smell whatever. There were earthworms present in the soil of a size which to me indicated an age of up to two months, but of this I cannot be sure. However, the largest were about two inches long and of a thickness near eight-gauge fencing wire.
The pasture itself appeared to be almost entirely composed of cocksfoot and white clover, but the cocksfoot, although evidently a profuse growth, was so small and narrow of leaf that it was necessary to examine it near the crown to realise that it was really cocksfoot. The leaf of the white clover was extremely small, a leaf being of the size of the half of a little finger nail. The nodules (rhizobium) on the roots were very white and clustered tightly under the crown in perhaps half an inch of soil.
Apart from a very shallow "renovation" at infrequent intervals over the years our spade work was probably the only time the soil had been disturbed.
One subdivision of the pasture area, which was without stock at the moment, appeared to have a good sward of grass ready for stock. We enquired as to how long since it was eaten off and were told it was both eaten off and watered fourteen days earlier. On our comment that the irrigation water had produced a very quick growth we were told that the growth following irrigation had been very slow but that a shower of rain only four days prior to our visit had produced the main result.
Here then was a soil never short of water and with all the advantages of regular and adequate dressings of superphosphate producing evidently a great bulk of pasture to carry its heavy stocking rate yet incapable of providing the necessary unknown factors or ingredients of health which would enable it to breed stock or even carry the same sheep for any lengthy period. On similar adjacent soil but with no extra water on the 17-inch or 18-inch rainfall country and with no added artificials, sheep could live, maintain good health and propagate their species. Surely there can be little doubt that the methods of irrigation and pasture management followed are very much at fault. The fact that the pasture is still high producing after so many years would be of little consequence if it was not supported by the natural unirrigated unfertilised land available, which, after all, does supply the unknown health factors that enables the sheep to live.
A totally different but equally interesting area came under my notice where exceptionally heavy cattle stocking rates had been carried on deep river silts. No superphosphate dressings were employed earlier, but when carrying capacity declined seriously superphosphate was applied without success. However, an examination with a spade disclosed the story. Although the rich black river silt soil was many feet deep, the spade showed that only the top inch or two was being used by the roots of the pasture species. Indeed, the main root of white clover had penetrated to two inches only and had then rotted off to an inch below the soil surface and produced laterals which grew out horizontally and just below the soil surface.
factors other than heavy dressings of artificial fertilisers can cause a soil to lose its fertility depth and restrict pasture roots to the top inch or two of a formerly very deep and exceedingly fertile soil.
A report from the last Grasslands Conference in New Zealand recorded that it was now generally impossible to breed from year-old heifers in a certain New Zealand district. The course of the district's pasture development had followed that of almost complete reliance on heavy applications of superphosphates which produced very large returns of butter fat.
not all growth factors in the soil are understood
These unknowns operating through the soil affect the plant, its health, and constitution, and its susceptibility to disease and pests. Through the plant an effect is produced in animals later, and in humans eventually.
[artificials should be used] more in the manner of a drug which will cure disease (the disease of infertility)
Chapter XVII Why Soil Conservation?
[landmen, farmers, and scientists are often so involved in their little day-to-day activities that they fail to observe the broader development/degradation of the land until it creeps up on them.] concentrated on the things of their special field, and the day-to-day work, and have tended to become even more remote from the broad environmental fields with which they should be most vitally concerned.
Agricultural pursuits must be adjusted to become methods which improve the soil so that the stability of the environment is preserved.
In man's attack on his problems he usually fights the obvious, the results rather than the causes, and through failure progresses to these causes and later to the real solutions. No doubt in the fight against soil erosion the results of erosion were fought and not the causes which he may have little understood.
There are two completely distinct types of man-made soil erosion and they have two different causes.
The first type is the erosion or washing away of soil and earths and decomposed rock and which is caused by the concentration of water flow. This type of soil erosion is a veritable land erosion and may start anywhere and at anytime. It is generally the result of public and private works that, in breaking both the small and major pattern of water flowing over land, cause new and unnatural concentration of water flow.
The second type is the soil erosion resulting from an agriculture which is not adjusted to its environment and is caused by the general change and deterioration of the soil's climate. This type of erosion may be local to one farm or regional and widespread. Its direct cause is from farming and grazing methods and practices that cause a loss of soil fertility. The agency which removes the soil is water or wind or both.
The first type of soil erosion is seen widely in the erosion that has resulted from road building. Wherever roads stretch out to conquer new land great erosion problems have followed. These are caused by diverted drainage
The methods that cure soil erosion depend on the degree to which it has broken the original land forms and profiles. The type of soil erosion that is most widespread in Australia's general agricultural areas still permits reasonable land management and can be cured by methods of land improvement and soil development that need not treat the erosion directly but cures and prevents it as incidental to better farm planning and soil and water management. I believe I have proved in my own work that the Keyline planning and development of land and its soil care is not only the economic and most effective method of preventing or controlling this type of erosion, but also the most profitable and logical.
If such a deteriorated landscape problem were put forward for Keyline management, then reclamation would proceed as follows: Disregarding the damage, the land shape would be first appraised in the same manner as would be done on a good farm, and, of course, backed up with a knowledge of the climate.
[for reclaiming lands with little economic value even after fixed] cheapest-to-make natural shapes is all that is required
avoiding the uncontrolled concentration of water flow
In Australian conditions farmers usually require more water, and particularly at those times when the natural environment does not provide it, so they should control and conserve the water. This also makes certain that the valley will have less run-off to handle and even at the same time increase its capacity to handle more than it could initially. Farming and grazing, as practices for the management of the environment, will produce a soil more fertile than the original soil and improve the environment beyond its best natural condition.
unnatural concentration of flow water may enter the land
If these inflows are not treated specifically, then wide destruction of the land form may occur.
[water] should be controlled at the immediate point of entry and transported by water conservation drains to a specially constructed storage.
To start at the beginning of modern-day soil conservation, wide land surveys were conducted in America to investigate the losses from soil erosion there, and determine the course that events would take if the problem was not attacked in a practical way. Prior to 1930 these reports indicated that about one hundred million acres of once productive land were seriously affected by soil erosion, and even half of it to the stage of complete abandonment. The continuing rate of loss exceeded the equivalent of a million acres of fertile topsoil each year and the rate of loss was sure to increase. However, despite these facts and the lessons of history, there seems to have been no widespread awareness of the march of soil erosion in the new world until what are known as the depression years of the early nineteen thirties. Then in America there started probably the greatest campaign to educate public opinion on the menace of soil erosion than ever had happened before in all agricultural history. No mad scrambling land boom ever approached in publicity the course of the "sale" of the great land menace of soil erosion. No other land subject ever received such wide and popular press support. Then later, when the wonderful press co-operation and response started to die down somewhat there grew up association after association, formed by public-spirited people, who, themselves "sold" on the reality of the menace of soil erosion and the need for action in the matter, wanted to keep it continuously in the public eye.
America, like the rest of the world, was suffering from the shocking and repeated blows dealt out by the great depression and their unemployment figures ran into many millions. Consequently the great "soil erosion menace" became a boon to many unemployed as the Federal Government, fighting the two national menaces of unemployment and soil erosion, started project after project, all of which had their impetus from these dual menaces to the nation. Agricultural officers were taken from their work in departments and became soil erosion experts as vast sums of money were poured into the battle. For a start the new experts seemed to forget agriculture, but in keeping with the virile spirit with which America tackles her problems when her people are really aroused, many of these officers became instead of agriculturalists, enthusiastic amateur engineers. But the American people were told that she was losing by soil erosion the equivalent of a million acres of fertile top soil every year, and there does not seem much doubt that this figure may have reflected the true position. The new experts therefore were going to fight this great battle and win it, and where should they concentrate their major efforts but on the biggest and best soil erosion gullies. So their requirements in plant and equipment got bigger and bigger until the new experts had tasted to the full the thrill of the direction of huge accumulations of big equipment.
Here in Australia, however, we did not have the spending at that time of even reasonable sums of money, and little, if any, equipment was forthcoming. By contrast in 1957 the Soil Conservation Department of N.S.W. spent the large sum of half a million pounds. Shortly afterwards Australia was in the second world war and it was not until 1946 that our soil conservation departments really got under way. In the meantime books on the subject became available for study and Australians had been sent to America to learn the American methods and become soil erosion experts.
"Why wasn't all the water conserved?"
The emphasis was still too much on water flow as a menace; water had to be got away from the farm land safely, was the general attitude of soil conservationists. Contour drains, contour banks, absorption banks, pasture furrows, grassed waterways became widely-known terms and the use of these structures spread slowly.
soil conservation generally worked and that it did stop soil erosion where the methods were applied properly.
In learning anything, mistakes are always made, and so the costs of improved farming practices are paid for by many landmen.
Soil conservation as an approach was never really necessary. Indeed, the accumulations of its mechanical procedures are not its own, but are borrowed from agriculture, ancient and modern irrigation systems, and from mining. To many laymen the use of the contour in agriculture is the invention, even the great inspiration, of soil conservation, but nothing could be further from the truth. In the study of aerial photography of Great Britain parallel contour lines were found, lines unseen from ground observation, which are interpreted to mean that contour working of land must have been practised in early Roman times
the landman's job is not so much to conserve soil as it is to develop soil
Soil is not dead, inert matter; it is alive and vital.
the successful soil conservationist naturally works himself out of a job
Agriculture is growing up and extending, and it must take a wider and more comprehensive view of all its own functions. If Keyline or any other equally good and broad environmental approach to land and water can automatically control soil erosion, eliminate the disastrous effects of droughts by preventing the waste of water and floods, and increase productivity, then the large staffs of Soil Conservation Departments could be very profitably employed on expounding the new approach and teaching it to farmers and graziers, and thereby adding greatly to the national benefit.
land and its problems must be seen as a whole and not as separate
CHAPTER XVIII Design and Construction Of a Farm Dam
In these writings I have tried to avoid the customary fault of describing any one thing or aspect as "the most important" in agriculture, because I see agriculture as composed of many factors, and all, in their respective ways, are important, since each is a necessary part and without one the rest mean nothing, or, at any rate, nothing that is permanent and stable.
The first of these two ways [to store water on a farm] is to make the soil itself hold a large storage, and the means of accomplishing this are widely applicable, greatly economic and highly productive.
Fertile soil will absorb the first two or three inches of rainfall rapidly before heavy run-off can start
soil could hold more water than all the huge 'big' dam storages built and projected
The fact that we have both flood wastage and shortage of water illustrates the need for a solution of the problem of rain run-off.
second type of storage, the farm dam or the farm irrigation dam
[lockpipes under the dam are better than syphons b/c they don't need to be primed and, more importantly, they allow drainage while the dam is being constructed]
On other occasions a miner may want a pipeline beneath the wall of his dam, and lacking experience may simply lay the pipes and build the wall over the pipeline with little thought that this could cause the failure of his dam. Water will tend to flow along the outside of a smooth pipe and make a tunnel of increasing size until the wall collapses
mix rotted grass, chaff or horse manure with the earth around the pipe on the theory that if water movement should occur the lightweight material will also move and tend to block up the porous area and automatically seal the leak. Surely this dodge is the invention of some hard-pressed mining man, and while it is difficult to prove that the practice works, it is known that when it is employed pipelines do not usually fail, and that they often do when no such care is taken. [or baffles]
Only sufficiently heavy steel lockpipe is, in my opinion, universally successful. [brittle pipes can break]
There are many failures that have turned out to be successes, and many of them go unrecorded
The word "dam" refers to and means the whole thing, including the valley or basin area below top water level, the water and the wall. This is a different meaning for the word to that generally employed for the "big" dam, where "dam" applies to the wall itself In the farm dam the back of the dam is behind the wall or the side away from the water. The inside of the dam is the water side. Parts of the wall are its top or crest, which is the roadway along the top of the wall. The wall has an inside and an outside or front and rear batter (or slope), the rear batter in behind the dam-the downstream batter. The particular slope of the wall is described in figures such as 1 : 2, which mean that a vertical fall of 1 occurs in a horizontal distance of 2. The wall has a foundation or foundation area which is the bottom of the wall shape on the prepared earth of the valley below it, but the bottom of the dam itself is the land of the site which is or will be below the water level of the dam when it is filled with water.
In preparing a site for a wall, the foundation area of the wall has two trenches, both usually of the same width, called first the cut-off trench and second the lockpipe trench. The cut-off trench runs the full length of the wall from end to end and in the finished dam is usually directly beneath the crest or roadway which is along the top of the wall. The lockpipe trench crosses the wall foundation area from front to back at right angles to the cut-off trench. The lockpipe trench then runs in the same direction as the bottom of the valley but is located to one side of the valley centreline.
a farm dam conserving 400 acre feet of water would be considered a very large farm irrigation dam, but a "big" dam more than one thousand times that size conserving 500,000 acre feet of water is considered of moderate size.
[farm dam can often open lockpipe to avoid disaster, big dams you must evacuate]
[the drains/swales filling a dam will prevent siltation. Big dams will often silt up.]
The essential design features that are to be provided for in the farm irrigation dams are listed below:
1. Site selection.
2. Constructional practicability of design.
3. Study of materials available to determine: (a) Texture-whether uniform or not. (b) Degree of compaction necessary for stabilising. (c) Correct shrinkage allowance. (d) Foundation area.
4. Height of freeboard.
5. Spillway size.
top width of the wall crest is wide enough to allow farm equipment to travel safely so that the dam can be always properly maintained. A good minimum workable width is 10 feet.
The critical factors in site selection are: (1) sufficient catchment available; (2) the contour shape of the valley at the proposed water line; (3) the valley floor slope; (4) suitability of earths for construction; and (5) suitable adjacent area for irrigation land.
a depth of water of 24 feet as against a depth of 20 feet will in many circumstances double the cost of the wall. It should also be understood that in considering a dam of this size, the extra four feet of water may double the conservation capacity of the dam, and for this reason the larger undertaking may become well worthwhile.
The site is then cleared of timber to a little beyond the water level contour (10 feet clear above this line is suitable) and down valley about 30 feet minimum from the YY peg. [YY = deepest part of the dam]
[more of P.A.'s detailed instructions on dam building that are pretty difficult to understand. Many pics to help out. I've said several times the entire keyline work needs re-written]
an examination of the materials should be made to a depth of two feet below the deepest excavation area indicated in the design. A few small holes made with hand tools or even a small auger may be sufficient. The material is to be examined for cohesion, stability and water-holding capacity. If the dampened material will roll into a small bar or sausage three-eighths to half an inch diameter three inches long and can then be bent without breaking into a curve nearly a half circle, cohesion is satisfactory, and so generally is the water-holding capacity. If this earth is very fine with no sand or larger particles it may lack stability, and so wall batters would be designed flatter than in circumstances of good stability. Very fine and uniform particle clays and very fine silt are the less stable earths. Silts generally also lack cohesion, so silt earth walls generally need the flattest batters. Water-holding capacity is low in sand and high in clays, so that if there is in the earth a little more of the clay fraction than is necessary to fill all the interstitial spaces between the coarser particles, water-holding capacity will be suitable, but where this condition is not met the earth will not hold water well and often not at all. In these cases special sealer blankets are employed. Generally they are of two types; selected clay is used to cover the whole of the inside of the dam and inside wall batter with up to two feet thickness of clay or, alternatively, bitumen emulsion products incorporated with the earths of the structure itself form the blanket. Of other methods sometimes suggested I have found none yet that are sufficiently effective and economically priced.
allowance for shrinkage of 8-1/2% is satisfactory. Generally, clay material shrinks more than mixtures of clay and sand.
A freeboard of three feet is suitable on most farm dams.
A spillway needs to be wide enough so that the maximum storm run-off likely when the dam is filled will flow through the spillway as a stream not much more than one foot deep.
From the point of the spillway at maximum water level of the dam the spillway is given a drop of 0.5% and the spillway section carried far enough around the land so that overflow water from the spillway cannot flow on to the back toe of the wall.
The lockpipe trench is cut in one foot deep from the Y line at the back of the wall and constructed under the wall site right through to the inside of the wall, and must be dead level (a horizontal line). The level of the trench throughout is the same as that of the low point of the valley on the YY peg. The lockpipe trench will then be one foot into the solid ground on the Y line at the back of the wall, but, according to the valley floor slope, may be four to seven or eight feet deep at the inflow end of the pipe on the water side of the wall.
Filling the Cut-off Trench: With the completion of the lockpipe trench and the cut-off trench, a chisel plow is brought in to cultivate to about four inches deep the bottom of the two trenches and the whole of the area of the wall site, particularly from the cut-off trench to the Z pegs, working parallel to the centre line of the wall. The roughing-up of this material, which is now the prepared foundation of the wall, aids the better bonding of the wall into the site.
[use anti-seep material around the lockpipe]
It is to be remembered that an irrigation dam will sometimes be filled with water and sometimes empty. The period of greatest stability for the inside of the wall is during the time when the dam is completely filled. The water helps to hold the inside of the wall stable. Its period of greatest instability occurs when the water is drawn from the dam and the dam becomes empty. Inside slumping and slipping of the earth of the wall towards the bottom of the dam is the manifestation of this instability. If earth is removed from inside the Z pegs, i.e., from below the inside toe of the wall (a universal fault in farm dam construction) during the early stage of wall construction, then fill material will later have to replace it. The result is that a greater length of material that will settle and shrink occurs at the most vulnerable inside point of the wall. If, however, the shape of the land below the wall is preserved in its original form (less the stripping of topsoil), then there will be a very much smaller length and total area of shrinkage surface and the wall is improved at what is usually a point of weakness. (See Fig. 14. )
If rain has fallen on the work area the whole of the wall section should be travelled and ripped up if necessary before starting again, so that continuous bonding of the earth as it is placed in the wall occurs satisfactorily.
In many types of earth work, moisture conditions are maintained within precise limits, but generally the only occasions that may be troublesome in the construction of a farm dam are when the earth is very dry and does not bond properly, or is in an overwet condition, causing clays to ball-up and leave air pockets in the wall.
the water conservation drain, which will later help to fill in dam, is not constructed until the wall is completed, so that run-off is restricted to the small natural catchment. It can, however, be even further restricted, if need be, by constructing that part of the water conservation drain only that is around the dam. Provision is then made for the disposal of the small natural catchment run-off through the spillway area of the site.
Some bulldozer operators like to concentrate on one spot to bring it up to its finished height, but this is bad practice, since it tends to work against uniformity of texture and proper bonding of the earths in the wall. Furthermore, areas of compacted stabilised earth are likely to be placed adjacent to areas of very loose earth. Shrinkage later would form large cracks between the different textured materials. There is a tendency also for bulldozer operators to push all the earth of the blade-load into the wall and leave it as a loose mound. This is avoided by the operators starting to lift the blade at the correct position on the wall so that the earth is distributed evenly. Again, there is a likelihood of earth being carried forward too far onto the wall site, the result being that much loose material is spilt over the back of the wall. This loose material in a finished wall tends to absorb a lot more rain than the rest of the wall, which, by increasing its weight, could cause sliding and slumping of the rear of the wall. The back batter of the wall should be maintained throughout by trimming with the bulldozer when it becomes necessary.
Sometimes a bulldozer operator "rushes-for-height", which often results in a concave line up the wall. The line up the wall should always be a straight line. A concave line encourages slumping
It is advisable to construct the spillway before the earth in the centre of the wall approaches its finished height, and when there is still plenty of wall area unfilled and available for the use of the spillway material.
The area of the dam is cultivated with a chisel plow in a single-run cultivation about three inches deep. The cultivation parallels the water level contour downwards (keyline cultivation), so that flow water later spreads as it flows into the empty dam. Next, the wall and the whole of the site is sown with the regular pasture seed mixture and combined with a dressing of fertiliser.
Our own valves are provided with a 2-inch constant-flow outlet on the water side of the valve closure, so that water is always available for such items of smaller supply as stock troughs, etc.
CHAPTER XIX Drains and Irrigation
Preferably a line is pegged rising at 0.5% right round the dam in the direction of the general rise of the country. (N.B. The spillway is usually on the downland side of a keyline dam.) Where the land shape has smooth contours, pegs 50 feet apart may be suitable for the construction of a drain, but it is preferable that Pegs be placed at closer intervals around the inside bends of valleys or the outside curves of ridges. When a peg intermediate between two 50-feet pegs is to be placed, it is not necessary to level in the peg 1-1/2-inch fall in 25 feet.
The pegs, when placed, represent the centre line of the embankment of the drain, so that when digging commences in the construction of the drain, earth is moved from a line some feet above the pegs, so that the centre line of the finished bank will coincide with the pegs.
Various implements can be used for the construction of the drain, from 3-point linkage attached-farm-graders through to the angle-blade large bulldozer. If a farm implement is to be used, a chisel plow should first cultivate the area above and below the pegs, and by just missing the line of pegs and leave them undisturbed. From two to four runs of the plow may be necessary, according to the size of the drain. The plowing of the land below the pegs assists the bonding of the subsequent bank material.
A single deep rip furrow made with a small tractor, travelling so that the downhill wheels leave the pegs undisturbed, is a further aid to the construction of the drain with the smaller type of equipment. The farm grader can then be operated, digging the earth from a regular distance above the pegs and throwing it towards the pegs; in this way half a dozen or more runs may be necessary to form the drain, including its bank. Throughout the operation the pegs should be preserved in their true position. Pegs are preferably about two feet high.
The whole area of the drain is cultivated once and parallel with the drain. The drain should be immediately sown down to the usual pasture mixture, together with an application of fertiliser.
It is desirable in the interests of the efficiency of the drain and the working of the property to have the pasture in the drain area of as good or better quality than the rest of the paddock, so that stock will keep this area eaten off.
In our own irrigation drains we generally provide a steeper fall (up to 1% grade) for the first 50 feet of drain from the lockpipe in order to counter an occasional tendency for a wet area to form near the outlet.
(NOTE: After irrigating, the drain stops are placed at intervals along the drain, so as to distribute any run-off rainfall.) [place all flags in the irrigation drain]
Keyline cultivation is simply cultivation with a chisel plow which parallels a selected contour line in such a way that when the parallel cultivation inevitably moves off the contour, the furrows oppose the natural flow pattern of the run-off water. The irrigation water then spreads evenly over the surface. The main art in keyline cultivation, when it is used in this manner as a positive control for the spread of irrigation water, lies in an understanding of the actual contour shape of the irrigation area, and in being able to select the line which is to guide the parallel cultivation, and then to determine the correct paralleling of this line, whether above or below it.
The first watering of a new area is preferably given in the morning, so that, with the mistakes and delays that may occur, the irrigating can be at least completed on the day it is started.
land thoroughly immersed or saturated in water for any period of time longer than one hour may suffer "drowning". The beneficial soil life, which, after all, produces the various factors which we call fertility in soil, require oxygen. The whole complex of this life can be seriously disturbed and changed if water is continuously left too long flowing over land. The ideal length of time is somewhat less than one hour.
The drain block or dam may be a piece of sheet metal cut to the shape of the drain and pushed into the earth. A few shovelfuls of soil on the water side of the block may be necessary in order to make the block effective.
The first irrigation of a new area should provide the information for future watering procedures. The length of time that it takes flow water to reach the lower side of the irrigation paddock is determined and it should be less than one hour. Later irrigation of the area would simply mean that the farmer controlling the watering would come back to the area every half to one hour period, according to this time of flow, and with experience after a few waterings it is a simple matter for one man to control three or four dams contained in an area of, say, 600 acres.
The paddock should be examined twenty-four hours after watering to determine the effectiveness of the spread, and unless sizeable areas have been missed, it would be unnecessary to especially irrigate a dry area. Thirty-six hours after watering the condition of the land should be such that all is moist but none is wet and none is dry.
Clay soils may allow water to flow at the first irrigation a relatively long distance rapidly. With the improvement in soil fertility due to well-managed irrigation, the distance water will flow then may be considerably reduced.
Soils that are poor and porous, such as some low-quality loams or sandstone soils and some granitic soils, will, by seepage, limit the distance of water flow in the hour, but with rapid fertility improvement the distance will increase.
the depth of cultivation is somewhat more critical in the light sandy soil, and, as a general rule, the cultivation depth of these soils should only be allowed to penetrate just enough through the major root zone. [after 1 year the soil will be totally changed. Earthworms will appear, etc.]
On "Nevallan", our experiment farm at North Richmond, we had country of very varied earth types. In one part it ranged from the shallowest grey soil through to yellow clay subsoil; others from yellow subsoil to soft yellow shales, even to medium hard blue shale, and all to be seen on the surface. There were other areas of sandy soil, with places where the sand was dean enough, and we used it in cement work for our buildings. On all these earths and under natural rainfall conditions, eight inches of highly fertile soil had developed in three years of Keyline treatment. During the next two years, the depth of this fertile soil had increased to two feet, with the roots of the pasture grasses well in evidence at that depth. Some green growth was continuous through the recent drought, the worst since 1944. A dramatic soil development during the fourth and fifth years had taken place naturally from the fertility that had been developed through the first three years of Keyline work.
Cultivation of the soil in its condition after two years of development by irrigation and keyline cultivation will be a different matter to the cultivation of the first year. It will now be practically impossible to cultivate too deeply, because of the depth of the developed soil. From then on the soil can be worked, when cultivation is needed, to as deep as the logical maximum that is suitable to the chisel plow and the particular farm tractor, with, however, the effect kept in mind that it will have on irrigation water.
The assumption, which I do not accept, is that the important factor is to keep the top inch of the soil in a good pasture-growing moisture condition and replace the loss of nutrients from this thin band of soil by regular applications of the appropriate artificial fertiliser. It is assumed that, in general, phosphates are deficient in soils and need to be replaced by regular applications of superphosphate.
The Keyline methods, however, assume generally that there are adequate minerals of all varieties present in the soil, but not necessarily in available forms or states, and it is good practice to make the unavailable minerals (phosphates generally being the critical one) available immediately by an appropriate application of superphosphate at the start of the development of the soil of an irrigation area. However, the rapid climax development of soil life due to the improved condition of the soil climate act on the existing but unavailable minerals and breaks them down rapidly into forms readily available to plant life. Chemicals, such as superphosphate, are, with advantage, used once or twice in the initial stages of soil development. Their purpose in Keyline is to provide rapid development of pasture root growth as well as pasture, so that -a basic food of soil life, dead roots of grasses, is in abundant supply as soon as possible. The continuous development of soil by the maintenance of the best possible soil climate right through to the depth of the zone of maximum root development during the first two seasons, continuously and progressively makes available the mineral elements of fertility and processed to their most perfect form by the natural factors operating on them. The effect is that in irrigation in Keyline the pasture is soon produced from some feet depth of fertile soil instead of from an inch or two of a very artificial growth medium.
CHAPTER XX The Choice of Farm Dam Designs</b>
Both the reservoir and the lower valley dam are larger usually than the high or keyline dam.
the same wall section may, in different circumstances of land shape, impound quantities of water varying from 2-1/2 million gallons to 150 million gallons (10 acre feet to 600 acre feet).
The minimum capacity of a dam that is worthwhile for regular and effective irrigation is 2-1/2 million gallons, and this should be a limitation imposed only by land shape and run-off. The minimum size for a reservoir may be eight million gallons, and for a lower valley dam perhaps twelve million gallons.
Reservoir Sites: The reservoir in Keyline is classified as a reserve water storage located. at an intermediate elevation between the high or keyline dams and the lower valley dams. A reservoir may be located at the low end of a large primary valley and just above the point where the primary valley joins a secondary valley; or where a primary valley flows into a creek, a river, a lake, or flows to a flat plain. A reservoir is also suitably located in the upper area of a secondary valley and in height somewhere below one or all of the keyline dams in the primary valleys
[reservoir] most suitable for fish stocking, and one on which other forms of pleasurable water activities may be planned. Dams, such as keyline dams, in which the water level is constantly changing, are not so suitable for fish stocking or as pleasure resorts.
the use-pattern for the stored water should be such that when some of the dams have storage capacity available by having been in use for irrigation, and run-off rain occurs, then no water will leave the property until all dams are again filled.
keyline dam should be designed to hold 1-1/2 times the annual run-off of its total catchment area, and this capacity is considered more a minimum than a maximum.
If a farmer or grazier can sell when most others have nothing fit for sale he can profit considerably. If he is also in a position to buy when others must sell, he is even better off.
the lower valley dam is designed to hold the overflow of all dams above it in the secondary land unit as well as all the run-off from areas below these keyline dams and reservoirs. It represents the last opportunity of conserving all such run-off before it leaves the secondary land unit.
The spillway of a lower valley dam, because of its generally larger catchment area, needs to be wider than those of the other two types of dams.
The spillway, according to this method, should be a width in feet equal to the figure obtained from the square root of four times the catchment area in acres. Using simple figures, the spillway of a dam having a catchment area of 36 acres is equal to the square root of four times 36, which is 12 feet, and the spillway of a dam having a catchment area of 400 acres is equal to the square root of four times 400, which is equal to 40 feet.
The use of the lower valley storage is similar to that of the keyline dam, it being a continuous-working and quick-profit dam. Whenever it contains water above the level of the lockpipe the dam is used continuously if irrigation is needed and can be put to advantage. Lower valley dam storage is not a supplementary system but is part of the regular farming and grazing enterprise.
It is suggested that the outlet of the dam is the most suitable point for a permanent or casual pumping set-up.
The arrangement whereby a pump and engine are placed somewhere around a dam, and, after pumping for a few hours the outfit has to be reset and often put down in the soft muddy area of the dam, is not a money-making arrangement, although in drought times the worst layout is better than nothing. Often after a dam has been constructed and has filled with run-off water and irrigating has been undertaken, the trouble of chasing the receding water into the mud begins; and it is a frustrating, time-consuming and money-wasting effort. Sometimes, too, a bulldozer is brought in to cut a trench from the deep part of a dam back to a spot on the water line to get at the deep water, so as to avoid changing the pump position. A small drag line excavator may be used for the same purpose. However, these things are evidence of not only inexperience, because the inexperienced can make a very good dam from a good plan, but the lack of proper forethought.
The art of land utilisation is largely a matter of making the best use of water
A contour dam may be used to advantage on slopes which contain no valley form. This dam is essentially a long earth wall of medium height constructed from earth which is excavated from immediately above the dam, and with wing-walls made to taper up land to above the water level.
In the flat lands all design features of the dams are flatter; the dams themselves are shallower; the water conservation and the irrigation drains are both flatter, but the irrigation drains are built up to flow water slightly above the level of the land. The land to be used for irrigation is also flatter and all the flat land methods of irrigation, already mentioned, can be used from the supply held in contour dams.
Features similarly associated with the location of the first valley dam are to be looked for in the site selection of a first contour dam for a property. It should be as high on the property as convenient
In the medium-size farm dam, a suitable freeboard height is three feet, but the circumstances of design in a contour dam suggest that this figure be reduced to two feet.
an allowance for settlement and shrinkage will be increased to 10%
The price per yard of earth moved in a contour dam of this wall height win be considerably less than in the higher wall dams. The average haul will be less, the push up the batter of the wall is shorter, and more of the operation, which is only shallow digging, can be performed in second gear. A reduction of 40% in earth-moving costs is to be expected.
We may suppose now that the water is all used in producing a spring crop and consider the empty dam. The dam area, which was provided during the construction with good draining slopes to the outlet, can then be cultivated, when dry enough, and sown to a summer crop. Because of the deep moisture of the dam area, a good summer crop could be produced in the driest of years. If, when this crop is nearly ready, heavy summer rains occur, the water conservation drain along the higher side of the dam, which filled the dam, can be used effectively to prevent run-off reaching the dam. The water conservation drain is blocked or breached before it reaches the dam and the section of the drain along the dam is put in order, so that run-off from the area immediately above the dam is made to flow out through the spillway.
Under the same climatic conditions, a grazier may decide to use the conserved water for flood or flow irrigation of a smaller area of pasture, say 20 to 30 acres, so as to enable him to have ample water available throughout the season.
Calculations for both dams show that the ratio of earth moved to storage capacity is somewhat better in the contour dam when compared with the ring dam, but the ring shape provides more water per acre of land under top water level, its average depth is a little greater and it has a smaller area of shallow water.
There is an idea in the minds of some that water has to be pumped "over the top" of the wall of such a dam. On the contrary, this is a disadvantage against pumping through a suitable pipe beneath the wall. The higher water has to be lifted the greater is the power required, or, alternatively, less water will be delivered for a given power.
Many branches of agricultural science have been improved considerably by utilising knowledge gained from mistakes, and it is hardly an exaggeration to say that science generally is largely the accumulated knowledge gained from innumerable mistakes.
After Care of Farm Dams: All newly-constructed farm dams, including those described in this book, are subject to change, The covering of all raw earth with soil and the sowing of grasses on every part of the dam and its immediate surroundings must be considered a part of the construction of the dam itself. Grass may grow and quickly cover the wall and the surroundings, but, even so, the wall will shrink and crack, and so needs inspection, and especially so during the first year of its useful life.
The earliest and best check on the general performance and accuracy of the newly completed dam takes place with the first occurrence of heavy rainfall. If it is heavy enough to promote considerable run-off, so much the better. To learn all that rain can teach, the farmer should get out in the rain with a longhandled shovel. He should walk the wall of the dam and look for little ponding areas on the wall crest, ponds which will later break out in one particular spot and flow water in a small but concentrated stream down one or other batter of the wall, and cutting little gutters. These first little gutters, if they are left, will form real flow paths for the continuing rain and so increase quite rapidly in size. It is therefore necessary to fill up the little ponds on the crest of the wall with earth from higher spots. The shape of the wall preserved at this very early stage ensures an even and harmless flow of water in the heaviest of rainfalls. Next, the four areas should be inspected where the constructed wall joins the banks or sides of the valley. Often water may flow along these junctions in small concentrated streams, and so should be diverted and spread away from the wall.
the new wall of a dam constructed of earth which was too dry should be controlled to fill more slowly, since the material of such a wall often lacks cohesion until it becomes slightly moist right through. If the first cracks on the water side of the wall of a new dam discloses dry, powdery earth in the wall, the water level may need to be lowered immediately. The very wet earth can slip off the dry, deeper material into the dam, and in doing so fracture the full section of the wall and result in the loss of a large part of it.
After or during the first heavy rain on a new dam, the first notable shrinking and cracking of the wall may take place. These movements are normal in a farm dam. They are a part of the design and construction of the dam, since the wall costs have been reduced by about half, because, instead of going to the expense of using sheepfoot rollers or pneumatic-tyred rollers to get complete compaction of the wall material, the natural compacting forces of settlement and shrinkage are allowed to operate. There are two types of wall cracking, and they are named according to their mode of occurrence--longitudinal cracking and cross cracking. The early longitudinal cracks usually occur near the outer edge of the crest of the wall and are often associated with the paths the tractor made along the wall. The looser earth on the outside of the path will pull away or shrink away from the more settled earth where the weight of the tractor compressed it. Such cracks are rarely a hazard, but they should be treated by raking earth to fill them a day or two after rain, when the wall dries out a little. just sufficient earth is raked to fill the crack. Neglected longitudinal cracks become larger and could, after further heavy rain, hold water in such quantities, which, in finding its way out through the wall, could cause a slip in the wall.
Cross cracking or cross-the-wall cracking is not usually associated with early settlement and shrinkage of a new wall. It may occur only after a dam has been first filled, and then all the water used and the wall has started to dry out. Though rarer, it is a more serious form of cracking if neglected or overlooked. These cracks may form a continuous split across the wall or be in the form of short cracks from the front and back of the wall to a longitudinal crack, and so form a crooked path through the wall. The cross cracks never or very rarely reach down the wall to the water level. Danger lies in cross cracks forming when the water level is reduced and the crack reaching down near to water level. Should flow water cause the dam to rise above the cracks, water will flow through the wall. If this flow occurs below spillway level, and is undetected, quite considerable damage to the wall can occur. Prevention of damage lies in filling in the cracks as with longitudinal cracks, but paying particular attention to the crack on the inside of the wall where it appears above the present water line of the dam. Here the crack should be rammed after filling, then filled again after ramming. Dry, more so than moist earth, is always to be used for filling cracks. Fine dry earth is probably the best.
I favour planting only the usual pasture mixture on the wall and fencing the dam off, or, alternatively, fencing the dam into a smaller paddock. Stock can be put on to graze the wall and the surroundings of the dam as part of the improvement programme, and the grazing should be controlled properly to these ends.
Failures in farm dams are generally presumed to arise from three main causes. The first cause is inadequate spillway size, which fails to convey the overflow water and forces the water over the wall of the dam. Soon a channel will be cut in the wall by the water, which, once it has got down below the spillway height, causes all the water entering the dam to flow through the break in the wall. The second presumed cause is from a low spot near the central area of the wall crest caused by inadequate or no allowance for shrinkage in the construction of the wall. The effect is the same as before; water flows over the low place in the wall, cutting a channel and destroying the wall. The third cause is presumed to be inadequate compaction of the wall, material, which allows heavy seepage to build up into a strong flow through the wall. All the water may be lost and the wall remain in position, or the flow through the wall may cause the wall above the hole to collapse into the flow and leave a break in the wall from the bottom to the top. Overtopping may destroy a new wall in 20 minutes and an older wall in two hours or more.
With the coming of the large bulldozer many men are unaware or have. forgotten what they can do without the bulldozer. While the bulldozer is a wonderful tool, farmers, by becoming too bulldozer conscious, tend to let a job wait, when the smaller equipment already available on the farm or even their own hand work can be used cheaper and more profitably. There is too great a tendency for farm workers to let a job or an earth works repair await the arrival of a bulldozer, a job which, considering the high hourly cost of a £10,000 to £15,000 bulldozer, they can do cheaper without it.
The accepted engineering counter to wave erosion is the provision of a riprap (heavy loose stone or rock) covering over the inside batter of the wall.
the prevailing winds in relation to the shape and lie of the dam will indicate the portion of the wall where the highest waves will strike.
A recommendation in the design of dams that are of a size where wind erosion is likely to be a factor is to design the wall with an extra foot of height and an extra foot of width for the one-third distance of the wall where the waves are most likely to affect the wall.
These suggestions should be effective in dams with a water surface 400 yards in front of the wall; and the allowance of extra width and height could be doubled for those very rare occasions of a farm dam having half a mile of water surface extending out in front of the wall.
CHAPTER XXI Rewards of the Balanced Landscape
For myself, the whole development of Keyline, of which the first experiments had no real point until the problem of producing good soil from almost nothing had been solved, has been a fairly long task.
so much trial-and-error work
miracle of soil change does not take place in one year, particularly when it is a drought year.
I suppose one could say that the whole scheme has constituted years of hard work, although I have never felt that way about it, as the improving of land always involved the proving of men too, and so the making of new and genuine friendships has made the work one of pleasure as well as all-absorbing satisfaction.
experiences that we have had over about twenty years, fifteen of which were in the agricultural field and all connected with farm water supply.
As for money, if the amount spent in one week in wartime were made available to finance the initiation of a scheme, then its completion would be definitely assured.
Addendum The Development of Narrow Tyned Plows for Keyline
The production of fertile soil from biologically inactive subsoil is not difficult and one technique is well known. We know that if sufficient quantities of dead vegetation and animal manures are available for composting, and the composted materials are blended into inert subsoils, rapid fertility can occur.
For broadacre farming however, there is never sufficient waste materials available. The soil and the soil life must be managed to produce its own composting material. Keyline techniques do just that and do it extremely well.
The plow business was sold in April 1964, with a proviso that P. A. Yeomans, and myself as the design engineer, had to keep out of the agricultural machinery business for a minimum of five years. The designs for a deep working, low disturbance chisel plow with the strength characteristics of earth moving rippers, a "sub soiler chisel plow" were moth balled.
They re-emerged, after this enforced hibernation, as the "Bunyip Slipper Imp" with "Shakaerator". This implement won the Prince Phillip Award for Australian Design in 1974.
The plow has an extremely strong, solid, rigid frame. The tynes or shanks are made from cast tool steel. They are narrow with a tapered leading edge. They travel through the soil with very little resistance, like a sail boats fin. The separate digging point is shaped like a long flat arrow head, tapering out to about 4" (100 mm) wide at the rear. The digging angle is very flat, only 8 degrees. A vertical "splitter fin" is incorporated on the top face, and becomes a vertical blade to the arrow head. In use, and in deep cultivation, the splitter fin initiates a vertical crack through the soil above, up to the surface. The side blades lift and loosen the earth between the shanks, and then allow it to re-settle. No mixing occurs between soil profiles and root disturbance is insignificant and gentle. After cultivation, the ground surface often appears as if undisturbed, yet is strangely spongy to walk on.
After my father's death in 1984
Greater emphasis is now placed on the location and size of the first dam constructed. This first dam now tends to be of greater capacity than previous designs called for. Fewer and larger farm dams now prove to be economically more viable.
the cash value of a soil is determined, firstly by the basic mineralisation within the soil. This is ordained by its geological history and formation. The farmer is not able to change this, outside the addition of some exotic trace elements. And the second determining factor, is the amount of humic acids within the soil, their age and their stability. The fulvic acids are here considered as subvarieties of the humic acids. If both abundant minerals and abundant humic acid is present, the soil is acknowledged as basically rich. Farming can, and does, change the content of humic acid within the soil. Most classic current farming practices in the Western World decrease the humic acid content of soils. The resulting soil deterioration manifests itself as, increasing dependency on chemical inputs, increased erosion and rising salinity levels.
Humic acid is not a simple acid, like hydrochloric acid or sulphuric acid. Humic acid is hardly an acid at all. When organic matter has been through all the biological processes within the soil, very large, relatively stable organic molecules are the ultimate result. Their formation is extremely haphazard and their actual chemical composition can have millions of variations. They are mildly acidic and so collectively they are described as "humic acid". Individual molecules can contain thousands of carbon atoms. They are so big that they can be acidic on one side and alkaline a little further around the same molecule.
For the farmer they have two very important characteristics. For a plant to take up an element for its growth, it must be in an available form. However, if the elements in the soil were in soluble form, they would have long since been washed, or leached away. Something else therefor, must occur for plants to exist at all. When acids break down basic geological minerals, nutritious soluble chemical elements become available, and these, fortunately, attach themselves loosely to the highly variable outer surface of the humic acid molecules. The element is no longer soluble, but it is readily available to the tiny root structures of plants and fungi. As far as a plant is concerned, the humic acid molecule is a supermarket, and its outer surface is the richly stocked shelves.
Carbon dioxide dissolved in rainwater forms carbonic acid. This carbonic acid breaks down the fine rock particles, replenishing the shelves in the supermarket. Also, biological activity within the soil can produce tiny quantities of acids, a thousand times stronger than the carbonic acid of rain water. These acids make available to the surface of the humic acid molecule, elements that would otherwise be totally inaccessible or unavailable.
Humic acid molecules can last thousands of years, and these were described in German literature as "Dauerhurnus" (dauer - German and endure - English). The long lived dauerhumus does not itself form part of soil biological activity. Other humic acid molecules however, do form that are much less stable. They can last anywhere from minutes to months. These molecules can, and do, get involved in biological activity. They contain, within themselves, protein and other similar structures containing nitrogen, as also do the long lived variety. Soil biological activity breaks down the short lived molecules and release a constant, and harmless trickle of ammonia to the fine plant roots, invigorating plant growth. This is "Nahrhumus", (nahr to nourish). Almost all of the nitrogen supplied to plants in healthy soil, is derived from this organic material within the soil.
It is well known that total soil organic matter constantly decreases with mono-cropping, and by the use of soluble chemical fertilisers, almost all of which kill earthworms and destroy microbiological soil life. The organic matter content decreases over periods, usually in excess of thirty years, and up to one hundred years, to a level of about half that in the original soil. Then a stability seems to be attained. This, it is claimed, proves that chemical agriculture does not continue to decrease soil fertility. I tend to believe that most biological activity has already ceased, and the organic matter, still in evidence by high temperature soil testing, exists only in the form of dauerhumus. These then are the extremely stable, but now empty, supermarket shelves.
So many problems are solved simply by increasing soil's natural fertility. And it all starts with dead plant material, air and water. Activity then starts, bacteria, fungi, actinomycetes and worms devour the dead plant material, die, and in turn devour each other. In the process, concentrated acids are produced that break down tiny rock structures, making available crucial elements in the life cycle. Complex humic acid molecules are ultimately formed. Some are broken down by more biological activity, producing ammonia for plant growth. Around others, the soluble newly released element become attached, but still available for healthy plant growth. Long chains of sugar like chemicals, polysaccharides, food stores for bacteria, are formed that bind the soil together. The tiny root like structures of fungi bind the soil particles in the same way. Small aggregates of these soil particles and sand and clays accumulate. In our hand we feel the whole thing as good soil structure.
Pieces of the less stable humic materials reform, and reform again until ultimately, relatively stable humic acid molecules are created. As the total organic content rises, earthworms move in and establish themselves. Their casts are a rich source of humus and their slimes and glues enhance soil structure. The soils ability to retain moisture, its "field capacity", rises dramatically and, to the farmer, rainfall patterns become less critical. This intense biological activity is the necessary "bio" in "biodegradable". Soluble heavy metals, poisons, become attached to the humic acid molecule and are no longer in solution and a threat. They won't be selected by the plants' discerning fine root structures.
The most rapid increase in soil fertility, and soil organic content in broadacre farming, is obtained by the utilisation, and the growth manipulation, of the legumes and grasses.
If conventional chisel plows are used to an excessive depth, for subsoil aeration and rain water retention, destructive mixing of soil layers results. For this reason, chisel plow use in Keyline required a program in which cultivation was only progressively deepened. Depth of cultivation was determined by taking a spade, and checking the depth of the root structures resulting from the previous cultivation. Tine spacings were kept at 12" (300 mm).
Using these new implements we can now recommend an initial cultivation depth of 8" (200 mm) or more. Any less than 6" deep the cultivating effect is similar to a chisel plow, with a typical V shaped rip mark of loose earth being formed. If a hard pan exists, and conditions are dry, large clods can still be turned up. By increasing the depth of cultivation, a point will be reached where clods are not produced at all. Horizontal fracturing spreads sideways from the plough point and surface disturbance is minimal.
Tyne spacings should be much wider than would be recommended for chisel plows. 24" (600 mm) spacings are perfectly reasonable. 18" to 20" (about half a metre) would be a good general guide. If horsepower is limited, it is wiser to maintain the cultivation depth, and, if necessary, decrease the number of tynes being used.
Within weeks of the first cultivation the decomposition of cast off root structures, following mowing or grazing, can promote soil colour changes from biological activity deep in the subsoil. This is quite impossible using a conventional chisel plow.
Cultivation, prior to cropping, using this plow at these depths invariably and dramatically increases crop yields. These dramatic increases are not always permanent. I believe that the dramatic increases result from exploiting soil layers, that have been "fallowing" for hundreds or even thousands of years. The minerals having accumulated on clay particles, as they do on the humic acid molecules. The dramatic increase in crop yields can only be maintained, by the inclusion of grasses and legumes into the cropping programs.
Again; So many problems are solved simply by increasing soil fertility.