What Krilium Might Do
By Dr. L DUDLEY STAMP
IT has long been known that the fertility and consequent productivity of soils depend upon a number of different factors, only partly related and of which at least three are outstanding. When the "Board of Agriculture and Internal Improvement" was createdas an independent body, though with Government backing, in 1793, it set itself the task of carrying out a survey of agricultural conditions in each of the counties of Britain. In each county a preliminary report was prepared, printed and circulated for comments before being revised or even completely rewr:tten before publication in final form. The soil survey which formed an integral part of the investigation was published as a plate to each county volume, and in some parts of the country these primitive soil-maps remain to this day the only ones for their areas.
What do they show ? Essentially they show soil texture, so that the map of Norfolk, for example, ind:cates "rich loam," "various barns," "good sand," "light sand," " clay " and "peat." At a later stage such terms as loam, loamy clays and clay were carefully defined, and the size of constituent particles made a subject of international agreement. Although the rise of pedology as a separate science has resulted in an emphasis on soil-forming processes and the d:fferentiation of the " hcr:zons " which make up the "soil profile," the texture of the soil has remained a matter of the greatest importance to the farmer.
The practised land-valuer by rubbing a sample of soil between his thumb and forefinger can judge the size and pro- portion -of the sand or silt particles and by the proportion of stain left the clay fraction. A good loam has a sufficient pro- portion of clay to enable the soil-to hold moisture and fertilisers, but not so much as to prevent free working at all seasons. To secure such a desirable combination the Chinese farmer will exchange so many hundred or thousand baskets of his soil for an equivalent quantity of a neighbour's; for the same reason the English farmer of a couple of generations ago would spread " marl " over his sandy lands or sea-sand on his heavy clay lands. Today the Fenland farmer may find an advantage in deep ploughing to bring the clay on to the surface of Fenland silt and peat: the allotment-holder will build up a heavy clay into a first-rate soil by digging in ashes. Thus texture remains a factor of first-class significance. , A second factor is nutrient status. Some soils have a natural balance of mineral salts and organic compounds which meet all the requirements of the grow:ng plant, but more often there are deficiencies in one direction or another which need to be met by the application of appropriate manures. A good loam will retain manures; with a loose sand they will pass through and the soil remains permanently "hungry."
But there is a third factor, and that is the,less known and less understood " structure " of the soil. Under certain conditions the mineral particles become aggregated so as to form "crumbs." When a well-worked garden soil is dried, it does not break down into a powdery mass of sand, silt and clay; it retains, until crushed, its "crumb-structure." Although a great deal of sentiment often enters into the perpetual argument of natural manures versus artificials, it is perhaps broadly true to say that, whereas the addition of natural manures, essentially decomposing organic matter, tends definitely to preserve and build up the crumb-structure of the soil, the use of chemical substances alone may tend to break it down. Herein lies the importance of dressings of organic manure.
Scientifically the nature of soil-structure may be imperfectly understood, yet every farmer knows the significance of "keep- ing his land in good heart." With a well-developed structure the soil is rendered capable of holding the fertilisers fed to it; it becomes retentive of moisture if naturally a light soil, but if a heavy soil it is less easily waterlogged and is workable through a greater range of climatic conditions. On heavy soils one of the effects of dressing with lime is to neutralise acidity, but another, equally important, is to create a set of physico-chemical conditions enabling the soil to retain and render available to growing plants other manures which may be added. - How can a good soil-structure be created or maintained ? This is one of the great objectives of what is commonly called good husbandry—in temperate latitudes such as our own con- stant cultivation by ploughing, harrowing and, where needed, rolling. Earthworms, soil bacteria and other minute organisms undoubtedly play an important part; so too does leaf-mould and stable-manure. Clearly, however, if it were possible to build up a good soil-structure from a variety of natural soils— from light hungry sands on the one hand to heavy intractable clays on the other—we should benefit by a great increase in productivity from lands otherwise of little value.
This is precisely what is claimed for the new substance to which the trade-name " Krilium " has been given. At the meeting of the American Association for the Advancement of Science held at Philadelphia on December 29th, 1951, the Monsanto Chemical Company of St. Louis gave details of this new "soil-conditioner." Dr. C. A. Hochwalt, vice-president of the company in charge of research, described krilium as a syn- thetic polyelectrolyte which "for the first time radically and immediately improves soil-structure." He stated specifically that it was not a fertiliser, but a synthetic substitute for the natural humus components normally plentiful in virgin fertile soils. One pound of krilium was stated to have (at a cost not exceeding $2.00 ,a pound) essentially the same effect on soil structure as 200 pounds of peat moss or 500 pounds of com- mercial compost. The rate of application was stated to range from 0.02 per cent. to 0.1 per cent. by weight of soil—let us say from lb. to 21- lbs. per ton of soil. Though extension to field-crops is possible, the immediate applicability of the pro- duct is thus to crops grown under glasshouse or intensive market-gardening conditions.
Scientifically the concept of improving soil-structure is basically sound and to a considerable extent, though not entirely, novel. The late Professor Bottomley, at that time Professor of -Botany at King's College, London, developed, in the years immediately before the First World War, the product which was marketed under the name of" bacterised peat." The claims made for this product were not dissimilar to those now made for krilium.
A world in which the increase in population is rapidly over- taking increase in output of food must remain vitally interested in krilium or any developments of the same idea. In addition, there is the claim that it renders soils less liable to erosion. Even more important, many troptcal soils in the great under- developed countries of the world present great difficulties in cultivation because of an absence of soil-structure. Does this new development mean that a new approach to the utilisation of tropical lands is in sight ?
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