Practical – – Agriculture.

Lake County Press, Issue 2461, 16 January 1913, Page 2

Practical - - Agriculture.

ORIGINAL ARTICLES (By F.S.C.)

Specially written for thia column

All Rights Reserved.

SOIL FERTILITY. Soil fertility is a terra that lends itself to many interpretations. Expressed in practical terms it can only ultimately mean productive power, and can only he really measured by the capacity of a given soil for crop production. lb has long been a matter of common knowledge that plants need at least ten different chemical elements for full and perfect growth. These are carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, potassium, calcium, magnesium, and iron. Four other elements are to be found in plants, but they are not generally considered as indispensable to the plant's well-being. These are sodium, chlorine aluminium and silicon. Plants extract ether from the air, from the soil, or from water these various substances and, after a series of comp'ex changes, build them into new tissue Of the ten substances that are considered essential to the plant's welfare, seven are usually present in largo quantities, whilst three are commonly deficient, namely, nitrogen, phosphorus, and potassium. This, it must be understood, does not of necessity imply that the total amount of these substances present in the soil is inadequate for the needs of heavy crops. It does imply, however, that at any given time the total amount of | what is termed available phosphoric acid, nitrogen, and potash is insuffi-, cient for the plant needs of heavy crops. Indeed, there is every reason to believe that only a very small proportion of the total amount of phosphates, nitrogen, and potash can he regarded as immediately available for the use of the crop. And the whole practice of manuring is based on the fact that these deficiencies in the available food supply of the so : l must be made good if heavy crops ar« to bo reaped. From the standpoint of the chemist, the fertility of a given soil is measured by the amount of these three substances present compared. with some arbitrary standard of fertility. It may be assumed, for example, that a good average soil would contain about .1 per cent, nitrogen, .1 per cent, phosphoric acid, and .2 per cent, to .4 per cent, potash. Lime is looked upon as a most desirable and valuable mineral ingredient in the soil, not so much because it is necessary plant food, as because the presence of a fair proportion of lime is usually indicative of a satisfactory physical and biological condition. The amount of lime actually present varies very considerably, but we may assume that a good average soil would contain from 2 per cent to 5 per cent. It must not be supposed that mere chemical analysis J alone will givo an infallible indication of fertility. The weak, point in an ' analysis obviously is that, while it re-] veals the proportions in which the several constituents are present, it; cannot state with accuracy just hoW| much of the plant food is available—i.e., fit for assimilation by the plant, j llt does, however, reveal the approximate total quantity of the several es-, : sential constituents, and thus indicates j ! the sufficiency or deficiency of the es-j , sential elements, and consequently ! affords a rational basis for inauguratI ing a series of tests with fertilisers.

It cannot be denied that the chemical aspect of the soil fertility has undoubtedly been unduly emphasised, and this has found expression in the exaggerated importance formerly attached to chemical analysis. But time and again it has been seen in practice that the physical conditions which regulate tho supply of air and water to the plant, and, as a corollary, the bacterial life are far more potent in producing a fertile soil than the mere amount of nutrient material present.

SUPPLY OF NITROGEN. Tho most important supply of nitrogen for tho nourishment of tho soil comes from tho farmyard manure produced on tho farm. Its composition varies greatly according to the food given to tho stock and the management of the manure. On an average a ton of ordinary farmyard manure may bo calculated to contain 12 to 151b. of nitrogen. 101b. phosphate of lime, and 7!b. potash, so that a dressing of 20 tons furnishes to the land about 2801b. of nitrogen, 2001b. of phosphate of lime, and 1401b. of potash, or as much fertili'sing material as is contained in 15cwt. of nitrate of soda, 6cwt phosphate of lime, and 10 cwt. of kainit, although of course the constituents in the farmyard manure are not in such a soluble form as in tho fertilisers. Tho small quantity of phosphate of lime in the manure may be noted.

During storage, farmyard manure is subject to great loss, especially of the valuable nitrogen,, a loss often arising to 30 per cent, or moro, which it is impossible, to prevent, although it may be lessened by good management of the manure heap. The most practical system of conservation is to tread the heap tightly down so as to hinder tho air from penetrating, and to keep tho heap moist by watering it with urine. A good effect is also obtained by putting layers of peaty soil on tho heap in tho course of its formation ; tlio soil has the power of absorbing volatile ammonia which would otherwise escape in tho atmosphere. Another plan which seems to be attended with success is to put a layer of well-rotted manure quite at the bottom of the heap, and to pile the fresher farmyard manure upon it. The gases emanating from the old rotted! manure combine with the ammonia] rising from the fresh manure, and! thus prevent its escape. Tho use of chemicals, such as gyp-. sum. kainit, and superphosphate, thrown on tho heap to prevent loss of ammonia lias not proved to be a practical remedy, because the quantities of the chemicals required to make the'

treatment effective are so largo that it does not pay to uh them.

HAY AND ENSILAGE. There is often much discission on the question when to cut clover for hay and ensilage. The different opinions expressed are very wido indeed, ranging from the time the clover comes into bud until the seed is nearly ripe. The stage at which clover should bo cut for hay or ensilage- must bo detennii - cd according to the circumstances, viz . the climate and the purpose it is intended, for instance, if it is to L| fed for lambs or sheep, it is usually better to be cut for hay before the stalks get too coarse, or the stock will not take to it so well; but if it is to be fed chiefly to horned stock or horses the necessity for fineness of straw is not a matter of so much importance, so long as the feeding valu< is obtained. Therefore, if intended for the former purpose, the crop should bo cut before it gets too far. advanced : whereas, if for the latter, in order to obtain & larger bulk of high quality feed, it is allowed to get ripe before cutting. CLOVER SILAGE. Clover silage is. claimed by many to be superior feed to clover hay, on account of its succulence and greater palatability, as well as its higher feeding value. The last-mentioned point is due to the fact that all the parts of the clover plant are preserved ir ! the silo, with a small, unavoidable I loss in fermentation; while in haymaking, leaves and tender part?, which contain about two-thirds of the protein compounds, are often largely lost by abrasion. This loss is greater when the weather is hot and the hay crisp. In spite of the fact that there have been many failures in the past in siloing clover, it may easily and cheaply be placed in the silo and preserved in . a perfect condition. The failures re- . -ported are largely due to faulty oon- . struction of the silo.

Experiment in clearing land of stumpi with the use of gelignite have proved most sncoossful in Tasmania. The heaviest stumps were lifted clear out of the ground, and split into several pieces, the roots having been cut first. Some 40 stumps in about two acreg were cleared in two and a-half days, although two men who had been working for two dayg previously had not completed the clearing of one ■tump.