FARM AND DAIRY

Taranaki Daily News, 27 November 1920, Page 10 (Supplement)

FARM AND DAIRY

eUILDItfG UP THE SOIL. (Specially Written for the Daily News,) A soil to be fertile should contain the following components:— (1) Humus, or matter derived from the partially decayed vegetable or animal matter. (2) Material- which is formed from broken down rocks, such as sand, clay, silt, etc. (.'!) Moisture in sufficient quantity. (4) Air, which is necessary for plant roots, and for many chemical changes that take place in the soil. (4) Bacteria, which are extremely small plants, and without which no soil can be really fertile. I shall now endeavor to show the importance of humus in the soil, and to indicate how the liumus content of the soil may be increased. Humu9, as mentioned above, is animal or vegetable matter in an advanced state of decay. It is dark brown in color, and this gives to soils that contain it in abundance a dark color. Its absence is denoted, to some extent, by a lighter colored soil. Subsoil contains practically no humus, and its yellowish color, and lack of fertility, are too well known to need further comment. Humus in the soil acts much in the same way as a sponge. It is capable of holding about twice its weight in moisture, hence its value in light, dry, sandy soils is evident. A soil that contains plenty of humus is therefore much more able to withstand periods of dry vrea l ther than a soil in which it is lacking or deficient. It also supplies a valuable plant food, on decomposition, supplying nitrates, which arc otherwise supplied by the addition of costly artificial manures, such as nitrate of soda and sulphate of ammonia. The various processes in changing humus into these valuable nitrates need not be discussed here, but it may be pointed out that they are the result of bacterial action, and are encouraged by having a sufficiency of air in the : soil, moisture, plant food, suitable, temperature, lime, and darkness. ■ , Clay soils, as is well known, are sticky and hard to work. They easily become water-logged, and when dry, set hard and crack. Early working of the soil is sometimes impossible, and iate crops are the result. But by adding humus to such soils, most of these disadvantages disappear. The soil becomes more friable or crumbly, and is easier to work. Water is able to pass through, and thus the waterlogged condition disappears. The soil becomes warmer and earlier. Better and earlier crops are the result. As may be gathered from what has been written, humus improves nearly all classes of soils. Consequently, one would think that every endeavor would be made to increase its content in the soil. But, on the other hand, it is for the most part absolutely neglected, and many tillage operations and cropping rotations arc constantly at work to deplete what little store of it may be in the soil. One of the best methods of increasing the supply of humus is by green-manur-ing. This consists in the digging or ploughing under of some rapidly growing, bulky crop, such as mustard, oats, clover, tares, Italian lupins, peas, etc. Oram crops, in which the stubble and roots remain in the ground, are also valuable, but. are not very bulky. If the crop to be ploughed under has been previously manured with a suitable mixture, so much the better, for subsequent crops will reap the benefits. When legumes, or pod-bearing crops, such a 9 lupins, clover, lucerne, peas, etc., are grown, the land is also enriched by the nitrogen gathered from the atmosphere by the bacteria, living in partnership on the roots of the plant. The plant supplies a home for the bacteria, which in return supplies its host with valuable food. Many barren, 6andy wastes in Europe have been brought under cultivation by ploughing in leguminous crops manured with basic slag and potash until a fertile soil had been built up. A similar practice should enable much of the now waste sandy areas of beach land near New Plymouth to be built up and rendered fertile. But in the reclaiming of sand-dunes the first step must be to stop the sand drift. This oould be 'brought about by special shelter belts, consisting of plants that are able to flourish under such conditions. The next step would be to get the ground covered with some suitable vegetation, leguminous plants, as mentioned above, being of most value. However, there is much experimental work to be carried out before hard and fast lines could be laid down as to the best methods of dealing with such lands. It must be remembered that greenmanuring crops deplete the soil of'.much moisture, and, unless due precautions are taken, the soil is liable to be too dry to ensure a good germination for the succeeding crop. The green crop should be dug in early in the season, so that the soil may benefit from the spring rains. Also the green crop must be in an advansed stage of decay before another crop i 3 sown. The soil should be made as compact as possible, so as to enabla the moisture from the subsoil to rise to the surface, and thus keep the young plants well supplied with moisture. But it must be remembered that the surface itself must not be left firm, or great loss of moisture will result from evaporation. A mulch' is therefore essential, that is, a loose covering of dry soil or other substances such as farmyard manure, etc, should be left on the surface Constant hoeing will give a suitable mulch, and, in point of fact, every garil.'Dcr shoul keep the hoe going regularly in .Iry weather. Wi'iile it is necessary for the soil to have liberal supplies of fresh air, yet the sail must not be of too open and loose a nature, or leaching will result. Leaching means the washing downward of plant l'ood from the soil to the subsoil, where it is unavailable to the plant. Mu<:h of the Taranaki soil is of a very porous nature, and should be consolidated. Tramping and rolling will provide this condition. Green manuring should not be carried out in districts that have an annual rainfall of lesii than thirty inches on account of the .resulting dryness of the land. Tn this respect, mustard is the least objectionable crop, since it will grow in than two months in autumn, and can tlKM.be dug in, leaving the ground in a suitable condition to catch the winter and early spring rains. On light soil, folding of stock on the green crop is sometimes done instead of digging or ploughing the crop under. By this method th* greater part of the humus is lost, to the soil, but, there is still a considerable gain, and manurial substances, such, as phosphoric acid, nitrogen and potash, are returned to the soil. The tramping of the stock also greatly consol datei the soil and imiti jw.tu""' «•* - At- *4, w *