SCIENCE, SOIL AND SPADE.

Northern Advocate, 22 December 1919, Page 1

SCIENCE, SOIL AND SPADE.

TRINITY OF REQUISITES

WORKING WITH NATUEE

Modern science has thrown a flood of

light upon the soil, its origin, composi--1 ion and the life processes occurring within it, but has given us no new revelation in regard to soil treatment. Cultural methods are surprisingly like 1 hey were in the dawn of history. Man, as we know him had not been long on the earth before he took the spade in hand, and it ,or its equivalent is still the sceptre of his rule or the emblem of his bondage—whichever way you look at it. It was not a willing subject that the command to earn his bread by the sweat of his brow was imposed, and had there been a royal road to harvests without labour mans ingenuity would have discovered it long ere this. What scientific discovery and research in regard to the soil have done is to explain the success of the cultural methods which have been in use from time immemorial; even the latest conception of the soil is being in a sense alive, owing its fertility to the host of bacterial organisations which live and move and have their being in it, tri- I umphantly vindicates the methods of successful cultivators in every age and i clime —methods which are entirely empirical or based upon observed results. OLD IMPLEMENT NECESSARY. Even mechanical skill, which is all the time trying to place in tho hands of man" tools to lessen labour and increase production, has not yet been able to oust the spade ,or very much improve upon its original pattern. All that the latter contrivances aim at is to reproduce the work of tho spade on a larger and cheaper scale; driven back upon intense culture—to make the most out of a small plot—the cultivator is still compelled to resort to the primitive implement. The primary objects of tillage or digging are to prepare the ground for the reception of valuable crops and to eliminate weeds. The soil is loosened to facilitate the movements of roots, for the incorporation of manure and the absorption of water; and a loose and mellow surface is created to sorve as a seed bed. All this can be done by fol- ' lowing the rule of thumb, without scientific knowledge, or even much imagination ,and too often the wielder of the spade has been a mere druge. The thinkers of all times have striven to inculcate higher thoughts about the earth, but it is seldom indeed that am "inspired ploughman" joins their ranks; there is something in unrelieved toil that dulls the imagination. NOT "MERE DIKT." Now, however, science has set before us sober facts which outdo the flights of poetic fancy, and are investing the soil with an interest, even for the manual worker, which it never iiad before. The man who in these days regards the earth beneath his feet as "mere dirt" is in danger of himself being called a clod. In a very real sense we are workers together with nature when we till the soil, and the more intelligent and sympathetic our cooperation, the more ready is Mother Earth to bring forth her increase. When we put our spade into the yielding mould, what are we doing, but assisting in the process of "weathering," which has made soil from the primeval rocks' The tiny grains of which it consists are the result of the grinding of rock masses and vast ice movements in past ages, the disruptive effects of heat, the explosive energy of frost, tho slow attrition of water, and the chemical action of atmospheric gases and decaying vegetation. The process is everlasting, and the mineral particles of the soil are continually getting smaller. In clay these particles are almost infinitely little, running into thousands of millions to the ounce, while in sand they are so large as to be easily countable, But the grains themselves are no more important than the spaces between them, those miniature caverns, carrying in size and extent with the coarseness or fineness of the soil, Tlrcso

spaces form passages continuous in ovoiy direction, though which air circulates and water percolates; into them the roots of plants force their way, and the microscopic fugi and bacteria, which promote the decay of dead vegetation nnd transform the remains into food for the higher plants, there carry on their useful work. FACTS LIKE FAIEYLAND. Could, we become sp fairy-small as to explore these caverns we should see the soil grains piled about us like gigantic rocks, their surfaces glistening with a film of water, which the intruding roots of the plants were busily sucking off. If we could measure the surface of all the grains in a cubic foot of the sandyloam which gives us such good gardening results, we should find they had a total superficial area of 36,900 square feet; in clay the area would go up to 110,500 feet, while ordinary sand would only give us 11,000 feet. The air which circulates in the soil passages contains rather less oxygen than the air we breathe, but sufficient for the requirements of the bacteria; nitrogen is abundant, and there is more carbonic acid than is good for humans. The roots of all plants, excepting those that dwell in marshes, must have air to breathe, and it is ono or the objects of tillage to keep it abundant and sweet by methods which approximate to ventilation.

One of the surest ways, to pxpel the soil atmosphere unci suffocate, the crops is to fill the soil interstices with water; moisture is essential, but when saturation point is reached plant life soon ceases. This introduces the important question of deep digging is to open up the lower strata of soil so that the rain water may penetrate downwards, leaving the surface layers aerated and wholesome for the plant root. An imaginary explorer in the soil spaces

found the surface of tho rock walls covered with a film of water —reeking wet we should say —while the air of the caverns was comparatively worm and dry. Had he been present after a heavy shower, he would have encountered streams of "free" water pouring downwards from the surface to the subsoil, ■and ia every direction where there was an outlet. WATER WISDOM.

After the passage of the free water the film would be found thicker, and wo should say that the soil moisture had bee,n replenished. Free water is only tolerable behind. "Film" water on the other hand is essential to the life of plants. It was at one time thought that roots in some way absorbed the solid matter of the soil, either mineral or organic, but we now know that plants feed entirely by suction, being unable to assimilate any nutriment Ihnt is not in a perfect state of solution. While clinging to the soil particles, the film of water, more or less charged with acids, is slowly dissolving the material and fitting it for absorption by the root hairs. The amount of water utilised in this way by plants is enormous; it has been estimated that not less than 37.1 pounds is required to produce 1 pound of dry vegetable matter, such as hay. A small amount of this water becomes parts of the structure of the plant but most of it is lost by evaporation through the leaves, having behind only the dissolved nutrients which it contained. It will be seen, then, that no small part of the work of tillage consists in fitting the soil to receive all the water required by the crops, and in preventing an accumulation which would nullify the effects of good husbandry. This and much more science tells us about the soil, making our work more interesting, and to that extent less irksome but still leaving the spade, lnbourionsly applied, as the type of efficiency.