Soil, its Life and its Climate
SOIL is the film of life which covers much of the land surfaceof this planet Earth. It is so thin that a light coat of paint on a large-scale modelof the earth would be much too thick to represent to scale the thickness of the soil.But it is the home of all earthly life and the great raw material of agriculture.We will never know all there is to be known about soils, but if a farmer understandsand has a feeling for soil life, he can manage his soil just as well as if he hadall the accumulated knowledge of all the scientists who are concerned with soil andsoil life.
Soil is composed of rock fragments of every size and variety,representing all or nearly all the minerals of the earth's crust, together with aninfinite variety of chemical and organic compounds made up of its rock particles,liquids and gases, all reacted on by the life that lives and dies in the soil andon the surface of the soil.
Rock is broken down by all the agencies of climate, sunlightand heat, freezing and thawing, wind and rain, and by gases as in the oxidisationprocess, but the disintegrated material is not soil until it is invaded by life;until plant life grows in it and animal life lives on it, and until soil life developsand lives and dies in it and thus forms part of the earth itself. Once soil has startedto form, the greatest influences on its ultimate development are always those factorsthat most influence these life forces of the soil. The higher the life forces withinthe soil, the greater is the fertility of the soil, and the maximum development thatany form of life may attain depends on its living conditions and its food supply.This truth, therefore, is of vital importance in the management of soil.
Monumental examples of this natural law can be seen in geology;for example, to mention only two cases, in the huge limestone deposits formed fromthe skeletons of a prehistoric life that developed rapidly in a favourable environment;and in the extensive coal deposits found in many parts of the world which representan ancient vegetable life that flourished in a suitable climate and was nourishedby a constant food supply.
Soil has a climate of its own. It is composed of the three factors,moisture, warmth, and air in combination. Good soil climate produces the best inpastures and crops. The natural soil climate is dependent on the effect of generalclimate on the basic geological makeup of the soil. Climate is a dominating influencein agriculture as well as on soil quality.
Soil is not, then, something that is dead. It is teeming witha great variety of life forms ranging in size from the submicroscopic viruses, throughbacteria, microbes, fungi, to the colossus of the various species of earthworms.A mere handful of warm, moist, fertile soil contains a life population that is astronomical.Some of the species of soil life multiply at fantastic rates when conditions aresuitable. Some species which increase by the mature individual dividing to form two,multiply so rapidly that if one single cell could conceivably have an inexhaustiblefood supply in good living conditions it would increase to a mass the size of theearth in a week or so. Many fascinating examples of the rapid rate of developmentof various species of soil life are contained in books on soil microbiology.
Oddly enough, although many distinguished soil scientists haveobserved these phenomena and commented on them, none of them seem to have made thenatural inference, namely, that soil development under optimum conditions can bevery rapid indeed.
Just about everything is food for some form of this soil life.Some live on others. Many are dependent on organic matter and some break down mineralelements for their food. The processes of living and dying form a variety of gases,acids and compounds. Minerals are acted on and altered to forms suitable for plantnutrition.
Represented within the soil is probably every factor of healthand disease of plant, animal and humans. This fact, somewhat clouded by magic, wasappreciated instinctively by primitive man, and was incorporated in the pattern oftribal rites and cures. Civilised man for a long time forgot it, but this soil healthfactor has gained a new significance in recent years through the development of theantibiotics--all constituents of fertile soils. Nowadays many of the chemical processesof the soil are regulated and reproduced in the laboratories in medicine, chemistryand industry.
A wide variety of some of the species of soil life seems tohave a counterpart in the glands, organs and secretions of all animal life.
While there are processes within the soil that may be detrimentalto crops and animals and humans, there is always a heavy balance favouring the healthfulnutrition of grasses, crops, animals and humans in all really fertile soils. Thesebeneficial or benevolent factors operate at their best when the conditions of moisture,warmth and air are most suitable for the optimum production of the best pastures.
Soil is dynamic and complete, forming and producing its ownfood supply. In a good soil the continuous production of vegetable matter, particularlythe newly dead roots of pasture grasses, supply the force for its continuing processes.
Good fertile natural soil was made or developed in a suitableclimate by plants growing in the soil, by animals and birds feeding on the growthfrom the soil, and by the complex of soil life living in the soil and processingthe necessary nutrients of plant growth. These same processes describe our agriculturalpursuits. Therefore, soil controlled by the farmer and grazier should rapidly increasein fertility and not deteriorate as so much soil has been doing for so long.
The development of soil is greatly influenced by climate. Inthe past, in my opinion, natural soil quickly reached its optimum development. Itwould then probably have maintained that particular fertility stage, only fluctuatingslightly according to the varying climates from year to year. It would have reacheda state of balance with all the factors that affect it, and remain relatively stable.
This idea conflicts with the general impression that soil takesgreat ages to form. Some rocks, it is true, decompose very slowly, but the formationof the live soil from rock particles can be very rapid in a good environment.
The study of soil life and all the soil-life processes is coveredin soil biology, and particularly soil microbiology. There is probably a lot moreto be learned about these various processes of the soil life than we yet know. Butprovided it is realised that to increase the quantities of vegetable matter in anenvironment that supplies the best conditions of moisture, warmth and air for soillife, is the outstanding way to accelerate the dynamics of this life, then the landmanhas the basic knowledge to greatly improve and increase the fertility of his soil.An improved soil climate itself acts to produce greater quantities of suitable organicmatter and especially from the valuable root systems of pastures.
Regionally, weather sets the course for the general agriculturalpattern. Agriculture is dependent on soil, and soil is largely dependent on the climatethat affects it.
Perfect agricultural weather or climate, if it were possibleanywhere, would soon produce perfect agricultural soil. Any soil, cleared of itsunwanted growth of scrub and trees and planted to the best species of grasses andclovers would also rapidly increase in depth and fertility. If the effect of climateon soil is fully understood, I believe we have a basic knowledge that will enableus to increase the fertility and productivity of any natural soil. We have a knowledgethat will allow us to increase the fertility of soil far beyond that which was producedin nature; but we need a new soil technology based on this knowledge.
I am well aware of the influence of rocks and their mineralparticles on the development of soil. Some rock types, for example the basalts whichbreak down rapidly and release the essential mineral elements of fertility, willquickly produce a fertile or at least a productive soil in climatic conditions thatwould not produce a similar stage of fertility in another type of rock. There hasalways been a wide range in the fertility of natural soil produced under identicalclimatic conditions over a range of varying rock types. Some rocks have been reformedagain after breakdown from original rocks and the disposition of, not only theirmineral elements, but also the plant availability of these elements, have been widelychanged. Some rocks will produce a complete soil with only one inch of decompositionfrom the hard rock; other rocks will need much deeper decomposition to supply allthe mineral elements of fertility. Granites, apparently identical, may differ widelyin fertility with only moderate variations in their general climatic influence.
Soil on earths formed by wind deposits may produce maximum productivenessfrom minimum climatic influence. On the other hand, former good soil can deteriorateinto poor soil by a changed climate that may cause the leaching down of a particularnecessary element. Clearing and cultivating have first of all made way for good grassand good crops. Then, almost dramatically at times, the land seems to collapse andwill not grow a crop or feed a sheep. The changed environment has caused a loss tothe soil of a necessary mineral element resulting from a deterioration of the soilclimate. Missing or unavailable mineral elements of fertility will never be veryfar away, but unless they are within the zone of plant roots they are not a partof the soil.
A suitable climatic change could rapidly improve a soil andbring within range formerly missing elements of fertility.
Disregarding for the moment the experiments being conductedby our Commonwealth Scientific and Industrial Research Organization (CSIRO) to producerain, there is little we can do to improve climate. But as the critical factor issoil climate, are there ways and means of managing soil and land to improve the effectthat the general climate has on soil climate?
It is most conclusive that some types of soil treatment andland management do deteriorate the beneficial climatic effect on soil climate. Theevidence is there in a deteriorated and eroding landscape. Before what is calledsoil erosion has its effect on soils that were originally of even moderate fertility,another very serious form of erosion took place. This is fertility erosion, whichis a presoil erosion, and paved the way to major soil losses. It is caused by a changefor the worse in the soil's climate, and the villain here is man.
While there are numerous ways of worsening the soil climateto reduce the fertility of soil, and we have no doubt employed them all, there are,in my opinion, as many ways of improving the soil climate and increasing soil fertility.
Good living conditions and plenty of soil-life food producea soil that becomes increasingly more fertile. Perfect living conditions, or whatamounts to the same thing, perfect soil climate, never exists and probably cannotexist continuously, but may be a present factor for short or longer periods onceor more each year, according to the particular general climate. During the time thatgood soil climate extends to the limit of the food zone, the soil-life communitiesdevelop very rapidly to climaxes. The climax period in these conditions is limitedonly by the available food supply.
As the various soil-life communities feed on each other, therehas to be a continuous new source of food to balance the whole ecology and biologyof soil. This continuous new source of food is some form of vegetable matter. Allforms of vegetable life become part of soil by these processes, and, I believe, thatthe greatest source of best possible food supply is contained in the newly dead rootsof the best clovers and grasses under a good pasture on which a variety of grazinganimals have fed.
Perfect soil conditions or soil climate involve a soil conditionin which there is ample moisture but not complete saturation, a degree of warmththat suits most of the life forms, plus sufficient air for the life that needs itbut not enough to dissipate overmuch warmth and moisture. These conditions producethe climaxes of soil life. To have maximum benefit they obviously must extend toat least the depth of the major root zone of a pasture.
If these optimum conditions can be induced in the soil, eventhe recognised poorest of soil, once each year for three years, as in Keyline, thenthese poor soils, or any soil, can be improved to something beyond that which thenatural climate produced. Further, once the greatly increased soil fertility hasbeen produced and maintained for three years it has the ability within itself toimprove its quality and depth without further treatment. Just how far or for howlong this self-contained improvement will continue I have no way of knowing, butI am quite certain that the correct answer will reverse the present beliefs and thatit takes much less time for man to build a bounteous fertility into his soil thanit does for him to reduce, deteriorate and ruin that fertility.
The practices and agricultural methods that deteriorate soilclimate and reduce soil fertility may take many years to produce a noticeably harmfuleffect on good soil, but only a few seasons to destroy the low fertility of a poorsoil.
Altered practices that improve soil climate and fertility cancreate, because of the fantastically rapid response of soil life to better conditionsand food supply, a highly fertile soil in a few short years; and it will always requirea much longer time to destroy this fertility than it need take to build it.
Perhaps the most dramatic evidence that there are many thingswrong in our agriculture is the effect that it has produced on the land in ever-increasingsoil erosion. I regard soil erosion as the perfectly natural reaction of land tochange its shape in keeping with changing conditions of environment. But the stableshape of land, with its cover of soil, before it is brought into the category ofagricultural land, represents a balance of all the conditions that affect it. Ifa soil that supports plant life and animal life has been produced naturally, thenthat soil is in balance with all the conditions that formed it and are continuingto act on it.
The factors that have affected and produced natural land shapeare very numerous, but those of its basic geology and climate are no doubt the dominatingones, since they produce or influence all the other factors that affect land shapeand soil class.
The features of land that make it suitable for agriculture areits soil coverage and its stable rounded or smooth form. These forms may range fromlarge and low, as in our flatter land, to small and high, as in our steeply undulatinghills and to all shapes between. Valley and hills are of a rounded smooth form.
To produce the best agricultural shape and the deepest coverof soil requires a climate, not only agriculturally suitable but one that has beenoperating for a long period of time over stable geological conditions. The deeperrich soils formed and shaped under favourable climatic conditions are very stable.Fertile soil has within itself capacities that resist change, or, as it is called,soil erosion.
When these natural soils and their land shapes are brought underagriculture many conditions may be altered and produce a lack of the former balance.The soil will eventually change and the land reshape itself to a new balance withthe new conditions affecting it. (See Pictorial Section.)
Fertile soil resists change or erosion, but changed conditionsmay reduce and destroy fertility, and then reshaping of the land form takes place.This is man-made soil erosion.
For illustration, we can take the extremes of two classes ofsoil, both in a similar natural undulating landscape, one highly fertile soil, theother a very poor soil, and consider the changed conditions that affect them whenthey are converted to agriculture.
Usually, the first thing to happen is that the land is surveyedand cut up into holdings or blocks with straight line boundaries which will be fenced.The fences cross hills, ridges, small and large valleys, watercourses and creekswith little regard to natural land divisions. Travelways, tracks and roads followthe fence lines and the first altered condition that may affect the land shape takesplace. Water flowing over land has natural flowlines according to the land shape,and falls in curved lines to the valleys from the hills and ridges. It flows as asheet, losing its natural flow path or pattern in the first depression. Roads andtracks cross these natural flow lines and cause water to concentrate earlier andin new places. The velocity of water moving on a hillside is greatly increased ona soil that did not develop in such conditions and is less able to support the flowwithout soil movement. When the velocity of water is doubled its power to move thingsis, theoretically, increased by about 60 times, and in the conditions as they affectsoil movement in erosion, by about 30 times. The poor natural soil then may commenceto erode immediately by the concentration of flow water caused by the road, but thehighly fertile soil, because of its fertility, will easily withstand this first slightconcentration. (See Fig. 4, Chapter 6.)
The answer to this first problem of agriculture is the betterplanning of land subdivision, and it must be based on a knowledge of the naturalflow movement of run-off rain so that the planning avoids causing unnecessary concentrationof water flow. Rain falling on the limited land area of a farm is fairly uniformall over the farm, but when rain reaches heavy general run-off proportions, thenthe water moving over the land varies greatly in volume and depth. Water which hasfallen somewhere else is flowing over every point of the land except the centre linesof the ridges and hills. The amount of flowing water is progressively greater fromthe ridge toward the centre of the valleys.
Now, once boundary fencing as above is completed, large-scaleclearing may be undertaken; preparation made for further subdivision and the landmade ready for plowing and planting to crops and grasses.
Every one of these operations in orthodox agriculture breaksthe flow lines of water movement, causing new concentration of flow. The very poorsoils show some erosion immediately; the highly fertile soil is completely unaffected.
Every plow furrow that crosses a valley, every vehicle thatmoves on the farm, crossing even the flatter gentle valleys, breaks the natural flowline of run-off rain water and steepens its path to the valley, causing new and increasingquantities of flow. Side by side with this mechanical change in the conditions thataffect water movement on land march others that directly and progressively changethe soil climate. All, or nearly all, the trees may have been cleared, allowing dryingwinds to have a worsening effect on the soil, which then does not hold its moistureso well between rains. And the period of time that optimum conditions for soil-lifedevelopment and plant growth exist is lessened. The dynamic forces of the soil areat first slightly, but then progressively, reduced.
The poor soil shows the effect quickly; the highly fertile soil.is apparently unaffected. It may show no positive soil erosion effect for many decades.
Reducing these damaging effects, general farming practices maybe improving conditions in other ways. The growing of plants in the soil and thefeeding of stock on the crops and pastures are in themselves the same processes thatform and improve soil. If the balance of all factors generally has the effect ofimproving soil climate, then the soil will improve and remain stable.
A property may be overstocked; concentrations of stock may firmthe soil and at first even improve it. Then a real compaction may set in restrictingthe former depth to which suitable aeration extended. Beneficial soil life is restrictedto the top inch or so of soil. The dead roots of the pasture grasses cannot formthe best food for the most beneficial soil life, because this life cannot live withoutair. The fertility factor of the dead root is largely wasted, the current formationof new products is lessened and the soil is then deteriorating by fertility erosion.Less, moisture is absorbed in the soil, more water runs off with increasing velocities,carrying soil with it. Apart from the erosion which is caused solely by the artificialconcentration of water flow, fertile soil must always suffer this fertility erosionbefore widespread soil erosion can touch it.
Concentrated water flow will move almost anything, but fertilesoil can be plowed badly, up and down hill, and everything wrong can be perpetratedon it, but it still will be little affected by soil erosion until the treatment hasreduced its fertility, reduced drastically its life and the current formation ofnew food or humus. The forces tearing down its fertile structure must be greaterthan the forces building them before soil erosion can affect it.
Some soils that farmers may believe are very fertile erode badly.But always such soils have lost their former power to produce year by year new orcurrent humus. Among the many products of fresh humus is the gum-like substance whichforms the crumb structure of fertile soil and resists movement. The good crops whichthey may still produce in good seasons, and the seasons affect them more and more,come from readily available minerals inherent in the original rock or produced inthe past by the soil's former biological fertility.
Land which once carried some of the most fertile soil on earthis now distinguished by its giant erosion gullies. It took decades of plowing, badplowing and cropping or wrong management, to start the serious erosion. Many of thecultivating implements of agriculture are condemned by the terrible land destructionthat followed their use, for example the mouldboard plow in the great corn beltsof, North America, the disk plow in the drier wheat areas of America, Australia andAfrica. It would, however, be just as logical to blame the destruction of land ona most popular tractor because it pulled the plow, destroying land much more quickly,as to blame this type of erosion entirely on the implements. The failure of agriculturaleducation or the general attitude of some early farmers to the land, the mistakenbelief that exploitative farming was good farming, the lack of farming experienceand knowledge by the early settlers, the failure to adjust the best in European farmingmethods to the new conditions of the new lands, the cheapness and abundance of goodland, the thoughtless and careless rush to produce for a profitable and expandingmarket--all these factors are causes of the erosion problems of soil that worry thenation and other nations today.
Cultivation equipment, to be effective, has to produce a mechanicalcondition in the soil that permits crops to be planted, controls unwanted growthand allows the crop to grow, mature and be harvested.
Cultivation according to how and when it is done can eventuallydestroy soil fertility and start serious erosion or stabilise, develop and improvesoil far beyond its natural state.
Continuous year-by-year cultivation to an even depth with orthodoxmouldboard and disk plows is likely to form quickly a new artificial soil horizonthat changes the soil climate and reduces soil fertility. The smashing and pulverisingeffects of many types of cultivation, if continued, change the soil climate by graduallysealing more and more with the first following rain, which restricts both the intakeof moisture and air. The most desirable type of cultivation at the wrong time ofthe year is still bad. It promotes the rapid loss of moisture in summer and on thelight soils in winter reduces the temperature of the soil.
Cultivation that promotes the best conditions of moisture, warmthand air in the soil together improve soil climate and promote fertility.
Any straight line cultivation or round and round the paddockplowing is tending to break the flow path of run-off rain, steepening its path andconcentrating its flow. Acting and compensating against this though, certain typesof cultivation, notably chiselling and ripping, may increase the absorption of rainand reduce flow. Again, if the balance of the factors improves soil climate, thesoil improves and its stability is preserved. If the balance deteriorates soil climatethe reverse is true.
It is not so essential that soil never be treated in such away as to deteriorate its climate as it is for the farmer to understand the processhe is using, and its ultimate effect, if continued, so that he can keep the generalbalance always in favour of his soil.
Some soil treatments or management processes which work againstsoil fertility may be necessary at times in the course of farming operations, butalways the more fertile the soil the better it is able to withstand damaging treatmentfor a time. Various types of cultivation are necessary in farming enterprises andmany cultivation processes are damaging to soil fertility. But just as surely, inmy. opinion, cultivating processes can be a great aid in improving soil climate andsoil fertility if the farmer understands just what he is doing.
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It seems that the aim must be to redesign every mechanical agriculturalprocess so that it has the effect of improving soil climate. Then every other usefulart and science of agriculture and property management will have greater benefitbecause each is applied or used on a fertile and improving soil.
Soil climate is so vastly important because, apart from itsinfluence on agricultural production, it is the dominating influence on the developmentof the soil-life communities. This life in turn is likewise very important, becauseits products, the products of its living and dying and reacting on the various componentsof soil, supplies the necessary nutriments for plant life. It is a necessary partor process of fertile soil. The more dynamically alive the better it is.
The farmer should know that as soil dries out so the soil lifedies out, but will regenerate again rapidly from its vital forces and eggs and sporeswhen soil climate is again suitable. He should know that cold soil reduces the forcesof soil life to a lower ebb; that moisture, warmth and air produce the climaxes ofsoil life; and, finally, that soil life feeds on every type of food, including otherorganisms of soil life, minerals and organic matter.
When soil has been eroded and almost completely lost, soil lifecan be regenerated in the dead earth by cultivating and sowing grass and cloverswith fertilizers to stimulate early growth, and by the introduction of stock. Somespecies of soil life are distributed by all classes of animals and birds from theirrumen glands and organs, and the wider the variety of the stock the more completeand beneficial is the whole complex of soil life.
Even without appreciating or knowing much about the soil lifehe cannot see, the farmer will know that his soil is as it should be when he cansee that it contains a large and vigorous population of earthworms.
During the early part of 1944 1 commenced to develop "Yobarnie".I was a well-informed and ardent follower of American soil conservation methods andthese techniques soon dominated the appearance of the property. Many experimentswere conducted on pasture and soil improvement, both with the strongly artificialfertiliser approach of our orthodox agriculture and the wholly organic methods. Bothmethods, when we irrigated, produced good-looking pastures, but we were never consciousof an earthworm population. I do not remember seeing, earthworms or their casts inthe paddocks at that time, but no doubt there were some present. Some years lateradjacent land was purchased and "Nevallan" was established. After two yearsof Keyline on this property, which was much more eroded than "Yobarnie",earthworms and their casts became so evident they could not be ignored. We commencedto take a great deal of interest in this remarkable phenomena. We dug, counted, measuredand weighed earthworms.
Suddenly they disappeared; there were no casts nor earthwormsto be seen. We found the earthworms with the aid of a spade, deep down in the earth.
Towards November they were everywhere again and ten times asmany were casting on the surface of the ground. They had again disappeared by December,but at the end of March the following year they were in their millions and were seenby some of our largest parties of agricultural scientists as well as by more andmore landmen. Now the earthworms were much larger. There were many more of the smallerearthworms, but the large ones--which we believed must be the older worms--were nowover fourteen inches long. Many visitors both from Australia and overseas told uswe had the largest population of earthworms they had ever seen. Other visitors saidthat they knew of only one area, the fertile Nile valley, which had a greater earthwormpopulation than "Nevallan".
However, the point is not the development of the earthworm populationon "Nevallan", which could be another story, but their function in thedevelopment of soil. Visitors have said to me, "Oh, yes, the earthworms followthe good soil", and others just as positively, "Once the earthworms areintroduced they make good soil". But we did not have any good soil on "Nevallan"when we started Keyline and we did not introduce earthworms there.
I believe that the earthworm is merely a part of the life processwhich is soil. When the soil climate is slightly improved a few more earthworms breedand stay alive and active a little longer. At the same time, this applies to manyother species of soil life which, although we cannot see them, increase in numbersby countless millions in a week. The minute forms of this life have a very shortlife cycle, but the earthworm, truly the giant of the beneficial soil life, may liveto a great age. I have not yet found a reliable reference to the age to which anearthworm may live, but I have concluded that the largest of our "Nevallan"earthworms must be up to four years old now. There are large numbers in all sizes(and size may be a reliable indication of age), up to fourteen inches long in theirshrunken, not stretched, length, with many over twenty inches long.
Many species of soil life require no other food than the soilor earth particles themselves. All they require to perform their work of making soilis improved living conditions, i.e., improved soil climate.