The basic principles used in Keyline of increasing the fertility ofsoils has not changed since they were first described in The Keyline Plan publishedin 1954. What has changed is the design of the cultivating equipment and the modificationof the techniques for soil building that the newer designs have permitted.

  The production of fertile soil from biologically inactive subsoilis not difficult and one technique is well known. We know that if sufficient quantitiesof dead vegetation and animal manures are available for composting, and the compostedmaterials are blended into inert subsoils, rapid fertility can occur.

  For broadacre farming however, there is never sufficient waste materialsavailable. The soil and the soil life must be managed to produce its own compostingmaterial. Keyline techniques do just that and do it extremely well.

  The Keyline processes for the enrichment of soil were actually welldeveloped before suitable implements were found that would handle the job. Earthmoving rippers were often used because of my father's familiarity with such equipment.Results with this equipment were sometimes spectacular, sometimes disastrous. Rapidchanges and improvements in soil fertility levels were, however, being achieved withever increasing success. At that time a Graeme Hoeme Chisel plow was imported intothe country by a long time friend. This design looked very promising and the implementwas tried out. It worked well and was commercially available.

  In June of 1952 my father and I were in the United States on anothermatter. While there, we called in at Louis Bromfield's well documented "MalabarFarm". The techniques of Keyline had, in my opinion, progressed well ahead ofwhat was being done by Bromfield.

  In Amarillo Texas we met Bill Graeme of the Graeme Hoeme Chisel PlowCo. A deal was struck where by we made the plow under their patent in Australia.The words and the concept "chisel plow" were unknown in Australia in 1952.The patent was found to be unenforceable in this country and so anybody could copythe designs. This inevitably occurred as Keyline ideas spread, so we were forcedto go our own way. The plow was strengthened considerably until it "could goany where the farmer was game to take his tractor". That was my father's designrequirements and consequentially, mine too.

  Keyline soil building techniques were then slightly restricted bythe limitations imposed by the plow itself and these are the techniques describedin the Keyline books.

  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 machinerybusiness for a minimum of five years. The designs for a deep working, low disturbancechisel plow with the strength characteristics of earth moving rippers, a "subsoiler chisel plow" were moth balled.

  They re-emerged, after this enforced hibernation, as the "BunyipSlipper Imp" with "Shakaerator". This implement won the Prince PhillipAward for Australian Design in 1974.

  The plow has an extremely strong, solid, rigid frame. The tynes orshanks 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 toabout 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 becomesa vertical blade to the arrow head. In use, and in deep cultivation, the splitterfin initiates a vertical crack through the soil above, up to the surface. The sideblades 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 andgentle. After cultivation, the ground surface often appears as if undisturbed, yetis strangely spongy to walk on.

  The Shakaerator is an off set heavy fly wheel, bolted to the plowframe, that assists soil shattering and reduces tractor horse power requirementsin most soil types.

  By then I had my own independent engineering business, and by constraint,not in agriculture. This was where the new plow prototypes were built. After my father'sdeath in 1984, my company took over the complete manufacture of the plow. Improvementscontinued and six new patents have subsequently been issued. Three of which havewon implement design awards at the Australian National Field Days.

  The rapid soil building processes of Keyline were no longer restrictedby the use of chisel plows, and the techniques were streamlined.

  In addition, the use of this new plow enables the soil to absorb highquantities of run off from storms, and heavy downpores. This is the runoff that normallyfills dams, and can often cause erosion. These effects have be catered for in thedesign of whole farm layouts. Greater emphasis is now placed on the location andsize of the first dam constructed. This first dam now tends to be of greater capacitythan previous designs called for. Fewer and larger farm dams now prove to be economicallymore viable. This first dam is sized and placed to so enhance the returns to thefarm, that future dams can become self financing by the farm itself. My brother Kenhas developed computer simulation design techniques by which such decisions can beidealised. Design errors are virtually eliminated in the process, and financial andecological viability can be assured.

  The Keyline soil building process is now much more rapid with theuse of this plow. Many clones of the plow have now been produced, often with interchangeablecomponents, and if used correctly these plows can be equally effective.

  The real value, almost one might say, the cash value of a soil isdetermined, firstly by the basic mineralisation within the soil. This is ordainedby its geological history and formation. The farmer is not able to change this, outsidethe addition of some exotic trace elements. And the second determining factor, isthe amount of humic acids within the soil, their age and their stability. The fulvicacids are here considered as subvarieties of the humic acids. If both abundant mineralsand abundant humic acid is present, the soil is acknowledged as basically rich. Farmingcan, and does, change the content of humic acid within the soil. Most classic currentfarming practices in the Western World decrease the humic acid content of soils.The resulting soil deterioration manifests itself as, increasing dependency on chemicalinputs, increased erosion and rising salinity levels.

  To produce good crops in rich soils it is generally only necessaryto maintain, within the soil, reasonable levels of biological activity.

  Humic acid is not a simple acid, like hydrochloric acid or sulphuricacid. Humic acid is hardly an acid at all. When organic matter has been through allthe biological processes within the soil, very large, relatively stable organic moleculesare the ultimate result. Their formation is extremely haphazard and their actualchemical composition can have millions of variations. They are mildly acidic andso collectively they are described as "humic acid". Individual moleculescan contain thousands of carbon atoms. They are so big that they can be acidic onone side and alkaline a little further around the same molecule.

  For the farmer they have two very important characteristics. For aplant 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 beenwashed, or leached away. Something else therefor, must occur for plants to existat all. When acids break down basic geological minerals, nutritious soluble chemicalelements become available, and these, fortunately, attach themselves loosely to thehighly variable outer surface of the humic acid molecules. The element is no longersoluble, 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 itsouter surface is the richly stocked shelves.

  Carbon dioxide dissolved in rainwater forms carbonic acid. This carbonicacid breaks down the fine rock particles, replenishing the shelves in the supermarket.Also, biological activity within the soil can produce tiny quantities of acids, athousand times stronger than the carbonic acid of rain water. These acids make availableto the surface of the humic acid molecule, elements that would otherwise be totallyinaccessible or unavailable.

  If the soil is devoid of biological activity, and the minerals inthe soil have been used up by growing crops, re-mineralisation of the soil can onlybe achieved by the much slower use of carbonic acid derived from rain water. I believethis to be a considerable, although unrecognised, justification for the "longfallow". It takes a long fallow, or simply a long time, to re-stock the shelvesin the supermarket. When only minimum biological activity can occur, then the conceptof "resting the soil", starts to make sense.

  Humic acid molecules can last thousands of years, and these were describedin 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 lastanywhere from minutes to months. These molecules can, and do, get involved in biologicalactivity. They contain, within themselves, protein and other similar structures containingnitrogen, as also do the long lived variety. Soil biological activity breaks downthe short lived molecules and release a constant, and harmless trickle of ammoniato 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 decreaseswith mono-cropping, and by the use of soluble chemical fertilisers, almost all ofwhich kill earthworms and destroy microbiological soil life. The organic matter contentdecreases over periods, usually in excess of thirty years, and up to one hundredyears, to a level of about half that in the original soil. Then a stability seemsto be attained. This, it is claimed, proves that chemical agriculture does not continueto decrease soil fertility. I tend to believe that most biological activity has alreadyceased, 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 nowempty, supermarket shelves.

So many problems are solved simply by increasing soil's natural fertility. Andit 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 devoureach other. In the process, concentrated acids are produced that break down tinyrock structures, making available crucial elements in the life cycle. Complex humicacid molecules are ultimately formed. Some are broken down by more biological activity,producing ammonia for plant growth. Around others, the soluble newly released elementbecome attached, but still available for healthy plant growth. Long chains of sugarlike chemicals, polysaccharides, food stores for bacteria, are formed that bind thesoil together. The tiny root like structures of fungi bind the soil particles inthe 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 contentrises, earthworms move in and establish themselves. Their casts are a rich sourceof humus and their slimes and glues enhance soil structure. The soils ability toretain 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, becomeattached to the humic acid molecule and are no longer in solution and a threat. Theywon't be selected by the plants' discerning fine root structures.

  Food producing plants grown on such soils are healthy, mineral richand nutritious, and extremely resistant to insect attack. Weeds and non-food producingplants cannot compete in rich soils. This is not just accidental but logically inevitable.

  For this all to happen, we must first structure an ideal soil environment,and then, if we can, we should water it.

  The most rapid increase in soil fertility, and soil organic contentin broadacre farming, is obtained by the utilisation, and the growth manipulation,of the legumes and grasses. The current model of Yeomans Plow was designed specifically,so that its use would create this idealised environment.

  If conventional chisel plows are used to an excessive depth, for subsoilaeration and rain water retention, destructive mixing of soil layers results. Forthis reason, chisel plow use in Keyline required a program in which cultivation wasonly 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).

  Because of the resultant damage to existing pastures, it was oftenrisky, and it was not advised to cultivate when pasture grasses were in short supply,or when approaching a period of, possibly, hot dry conditions.

  Using these new implements we can now recommend an initial cultivationdepth of 8" (200 mm) or more. Any less than 6" deep the cultivating effectis similar to a chisel plow, with a typical V shaped rip mark of loose earth beingformed. If a hard pan exists, and conditions are dry, large clods can still be turnedup. By increasing the depth of cultivation, a point will be reached where clods arenot produced at all. Horizontal fracturing spreads sideways from the plough pointand surface disturbance is minimal.

  Tyne spacings should be much wider than would be recommended for chiselplows. 24" (600 mm) spacings are perfectly reasonable. 18" to 20"(about half a metre) would be a good general guide. If horsepower is limited, itis wiser to maintain the cultivation depth, and, if necessary, decrease the numberof tynes being used. In this way little pasture damage occurs, good deep aerationhas been achieved, and enormous quantities of storm rains can be absorbed beforeany run off occurs. Even with no following rain, very little soil moisture will belost. In many instances plant roots will gain access to otherwise unavailable subsoilmoisture.

  The subsequent grass growth should be mown, or heavily grazed by overstockingto achieve the same effect. Stock should be removed promptly to permit rapid unhinderedregrowth of the more nourishing pasture grasses. Subsequent cultivation should berepeated at or about the same depth. These Keyline stocking techniques are detailedelsewhere.

  Within weeks of the first cultivation the decomposition of cast offroot structures, following mowing or grazing, can promote soil colour changes frombiological activity deep in the subsoil. This is quite impossible using a conventionalchisel plow.

  Cultivation, prior to cropping, using this plow at these depths invariablyand dramatically increases crop yields. These dramatic increases are not always permanent.I believe that the dramatic increases result from exploiting soil layers, that havebeen "fallowing" for hundreds or even thousands of years. The mineralshaving accumulated on clay particles, as they do on the humic acid molecules. Thedramatic increase in crop yields can only be maintained, by the inclusion of grassesand legumes into the cropping programs. This is to promote biological activity, andthus maintain the supply of minerals and elements.

Again; So many problems are solved simply by increasing soil fertility.

Allan I. Yeomans