AERATION OF SOIL.

Pukekohe & Waiuku Times, Volume 4, Issue 117, 6 December 1915, Page 1

AERATION OF SOIL.

The aeration of soil depends essentially upon the structure; the more porous and Inoße the eoil is the note complete is the aeration. Natural factors and artificial factors (cultivatmn) that assist this aeration atra many and varied. As these (actors are almost universally Known, we need not mention them. One natural factor, fcowever, that has a great connection with aeration, and to which the average person is not inclined to place much credit, is the earthnorm. Earthwurms play epecial roles in ordinary soil. The role that concerns us here is: By the tunnelling carried out, and the passages made, due to their activity, they render the coil more porous and better aerated. In other words the soil becomes mellow, thus promoting breathing in the roots and, consequently, growth in the crops. The excrement deposited likewise serves to render the soil more pliable an d porous. They also facilitate drainage. The effect of these animals will be patent to anyone it be can realise that it has been calculated that there may be ae many as 40U,000 in two and a half acres of land. By admitting air to the soil, more plant food is available, the soil is made warmer, drainage assisted, the soil broken up, breathing promoted, and, in fact, a large number of definite advantages arising from admitting air, and which will be seen by anyone who pays a little attention to the matter.

Mr Benjamin Wilson, writing in the Queensland "Journal of Agriculture," eays:—"Loose soil is a mixture of solid constituent;, water and air. It is the laßt-named that we will deal with. Air in the soil is a most important point not considered by many people, though it is absolutely necessary to the successful growth of the crops. All'living subterranean parts, like all other living parts, require air —oxygen—for breathing. Only such plants that have large air spaces, connected by passages, can thrive in soil deficient in air; for instance, in very wet soil where the ground water is at the surface. All other plants would die through suffocation. The reason for this is that ticoholic fermentation and the evolution of carbon dioxide ia set up, with the inevitable result of death and putrefaction. In soils poor in oxygen decompositon takes place in a totally different manner from that in aerated soils; humic acids are formed in great quantities, so that the soil becomes sour. Air in the soil differs slightly in composition from that in the atmosphere; it contains more carbon dioxide and less oxygen, particularly so in the subsoil, because of the respiration of subterrnean organs, bacteria and animals, and the decomposition of organic bodies. The amount of carbon dioxide varies with the quantity of organic matter in the soil, the crop, the method of cultivation, Ihe contour and humidity of toe land, the size of the soil particles, the depth of soil, and the temperature (season)."