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GARDENERS' CHRONICLE 



the simple substances out of which it was formed, and, 

 with an exception, all the stored up energy is dissipated. 

 The old life becomes cleared away and the ground is left 

 clear for new life ; the old plant tissues are converted into 

 food for another generation of plants, and the process 

 of dissolution and decay affords the means whereby more 

 life may manifest itself. Gradually a whole population 

 of the most varied description springs up in the soil, feed- 

 ing on those plant tissues, deriving its energy for the 

 most part from the energy stored up during the lifetime 

 of the plant : and reversing completely the changes ef- 

 fected by the plant. 



The above mentioned exception to the dissipation of 

 energy is seen in the case of coal in which little, if any, 

 more than the initial stage of decay has been reached ; 

 the only change being that the plants composing it have 

 lost their green color, while the energy which they ab- 

 sorbed from the sun during their life has been stored 

 up for the use of the human race in the various processes 

 of our very complex modern existence. 



A complete cycle of changes is continually taking place- 

 between the soil and the plant. Starting with certain 

 simple materials, the structureless substance in the plant 

 cells, known as protoplasm, builds up complex plant 

 substances, fixing the sun's energy by means of *:he trans- 

 former situated in the leaves, called chlorophyll : this is 

 the constructive part of the cycle. When a plant dies 

 and its material is returned to the soil the other part of 

 the cycle, the destructive change, begins ; the complex 

 substances are broken down and are resolved finallv into 

 the simple substances with which the change began. The 

 soil is the medium in which this second part of the great 

 cycle of life goes on. It is so bound up with the cycle 

 that one cannot think of it apart from the changes oc- 

 curring within. This is the great distinguishing feature 

 of the soil, marking it off sharplv frorii a mere heap of 

 mineral matter. 



rROCESSES INVOLXED IN Fdlor.VTION OF SOIL. 



Some of the jirocesses involved in the formation of 

 soil can be observed where any great masses of earth 

 are thrown up from below the surface and allowed to re- 

 main, or in the case of landslips from cliffs or mountain 

 sides, in all of these we have a heap of virgin mineral 

 matter. For many years this will be bare of vegeta- 

 tion although we may be sure that plant seeds will have 

 been blown in upon it, or carried by birds. But in the 

 course of time minute and insignificant plants will begin 

 to appear which will be found to be of an entirely dif- 

 ferent character from those prevailing upon the sur- 

 rounding land ; until conditions are brought about which 

 will render the more prevalent local type of flora pos- 

 sible. 



The great interest now being shown in soil forma- 

 tion and the many practical lessons probably to be 

 learned have induced some Experimental Stations to 

 form permanent beds of raw virgin earth dug up from 

 beneath the surface and they have commenced systematic 

 botanical, bacteriological and chemical observations of the 

 natural changes taking place, and in other ways studying 

 Nature's methods connected with it. But Nature never 

 hurries, and the process nf soil making is very slow under 

 natural conditions. 



The question now arises, and it is a vitally important 

 one — Can we control the process of soil making and in- 

 tensify those processes taking place within it that are 

 beneficial to plant life? 



Our next step will be to discuss ways to these ends 

 and why certain methods of handling the soil are likelv 

 to bring it about. 



THE PROCESS OF SOIL MAKING, 



As regards the mineral matter of the soil, it, from the 

 point of view of ordinary practise, lies in the main out- 

 side our control. It is true that in Europe for many 

 centuries something was done in special cases in this 

 direction — especially in Belgium and Denmark up to just 

 before the war — by adding clay to very sandy soils and 

 also sand to soils which required to be made lighter. 

 But in these days this work is too expensive to be prac- 

 ticable in the case of those making a living out of the 

 land, and further, gardeners and farmers have for the 

 most part learned how to manage soils of different types ; 

 they have evolved systems and methods suitable to 

 sandy soils, to loams and to clays; the mechanical tex- 

 tures of the types which are extreme in either direction 

 can be easily and inexpensively modified by green manur- 

 ing, and the mineral constituents can be added in a 

 concentrated form which was not possible before the 

 age of chemical fertilizers. 



At the same time, upon a small scale, in a garden 

 where results are more important than expense much 

 can be done. For instance, one may have a sandy soil 

 and wishes to impro\ e it for the purpose of making it 

 better suited for the purpose of growmg roses ; in this 

 case the addition of clay is indicated, by which means 

 the sand}- soil can be changed into a loam. 



It is now, known that oiu" efforts should be directed to 

 increasing the organic matter of the soil, this is much 

 more easily under our command, and it is in this direction 

 that control of soil making and improvement principally 

 lies. This is readily and cheaply effected, as above men- 

 tioned, by the turning under of green crops, a point of 

 practise which was discussed in the October issue. 



There is another factor in soil making which can also 

 be controlled — the securing of conditions necessary for 

 the decomposition, of organic matter, as there seems to 

 be no getting away from the fact that the nutrition of 

 plants in the soil is primarily bound up with the decom- 

 position of plant and animal residues. In their original 

 state when first put into the soil these residues are not 

 onl)' valueless, but are even harmful, to the plant, it is 

 only after decomposition that they begin to be valuable. 

 Therefore the speed and completeness of the decomposi- 

 tion are of great importance in soil fertility. 



The work of decomjiosition is entirely carried on by 

 living organisms, and although larger species, like earth- 

 worms, assist in the dissemination of the material, the 

 change is practically begun and comijjeted by bacteria. 

 These soil organisms will do their work thoroughly if 

 given a chance : the object of the gardener should be to 

 see that they get their chance. 



ESSENTIAL SrBST.JlNCES OF THE SOIL. 



In these days when science has invaded the kitchen 

 and scientific dietary is more or less studied by house- 

 keepers, the fact that the more important components 

 of berth meat and vegetables are protein, carbohydrates, 

 fat, cellulose and mineral matter, is not unknown. All 

 these substances were originally formed by the plant 

 from material contained in its food which it derived 

 from the soil and, in the case of meat, were conveyed to 

 the animal through the food the latter consumed. These 

 substances are all of a complex nature, and in whatever 

 form they are returned to the soil, whether in that ot 

 animal manure, bones, vegetable matter, and such like, 

 all the complex substances have to be resolved during 

 decay into the simple substances which the plant took 

 from the soil in building them up. Each of the complex 

 substances is not only attacked by a special species of 

 bacteria which has no power of acting upon any other 

 substance, but the various stages of decomposition 



