WHAT FARMERS OUGHT TO KNOW.

Temuka Leader, Issue 1165, 15 April 1884, Page 3

WHAT FARMERS OUGHT TO KNOW.

AGRICULTURAL CHEMISTRY. (Written specially for this Paper.)

The importance of phosphoric acid and ammonia in the food of plants has been already alluded to. These compounds I form the bases of several artificial manures. The famous superphosphate is, of course, a phosphoric acid manure; nitrate of soda is an ammoniacal one. The establishment of works near Christ- [ church for the manufacture of this former substance, will doubtless prove a great boon to our farriers, since by successive cropping there is nothing the land iis sooner drained of than of this important food constituent. The superphosphate, , we all know, is made by heating bones with sulphuric acid. The objects of this process are to convert the insoluble material into a soluable one, and to procure the manure in the finest division possible. Bones are composed of earthy salts—compounds of lime forming fully one-half of the whole bone—and gelatinous compounds. The earthy salts themselves make but a very brittle and fragile framework, gelatine forming the connective tissue and giving touglmess and strength to the whole mass. The chemical changes the ordinary phosphate of calcium undergoes when under the influence of sulphuric acid are rather complicated, and we refrain from trouIbling our readers with them. When young cattle are put on land their bones have yet to form, and they require a large quantity of the phosphate. V.

Suppose the cattle, having reached maturity, are removed, and their bones, on death taking place, not returned, the soil will have been deprived of a lirge quantity of its constituents. The land also will be bo much the more unfit for rearing another lot of cattle on. In this way soil, once excellent pasturage, becomes totally incapable of bringing cattle to a healthy maturity, The consideration of bone-forming m .terial illustrates the close connection between ihe growth of animals (man included) and the constituents of the soil. Plant life is the medium which prepares the components of the soil for use by animals. Vegetables are the chief source ot boneforming material in the human body. A common fault found with colonials, is that they eat too much meat and too little vegetable food. One of the consequences of this, we understand, is that there is an insufficiency of material for building up the bony structure. The superphosphate having been produced by chemical means, is in exceedingly fine division, in such a state indeed that could not be produced by crushing or by any other mechanical means. A crop of turnips, we have already Been, is greatly benefitted by the addition of this manure, since turnips contain a comparatively lar«e amount of phosphoiic acid,

Passing on from the superphosphate — the type of the phosphoric acid manures —we come to guano, soot, and nitrate of soda —all ammoniacal manures. To these might be added sulphate of ammonia. In stating that coitain manures are cepsndant for their beneficial effects on nitrogen or phosphoric acid, it must be remembered that they do not consist entirely of these substances, but they also contain small quantities of some other salts which in many cases seem to do as much good as the preponderating constituent itself. The conversion of nitrogen into immonia and its adaptation for first plant and then animal food have been so often touched on that it is quite unnecessary to recapitulate. Guano is a natural product, and is obtained sometimes in very much adulterated forms. The adulteration of guano is so cleverly accomplished that the eye of an expert cannot detect it. In such cases chemical analysis is the only resource, Soot contains a email amount of nitrojen, and nitrate of soda—or chilia saltpetre is beneficial owing to the nitric acid it contaijs.

Gypsum or sulphate of lime is a manure that has been used to some extent. Its power is that of fixing the volatile caibonate of ammonia, converting it into the moie stable sulphate. Common salt is another compound sometimes applied to land. It enters into the composition of many crops, especially turnips, grasses and potatoes. Since it is a necessity in the food of man, we find it in the natural substances destined for his food. In some cases salt (chloride of sodium) is deficient in the soil—particularly in land far away from the sea—and then it is spplied artificially. Vegetable ashes are also capable of improving soil. In the North Island the system of burning bush and fern has proved very advantageous. On the ashes thus produced grass seed is sown, and splendid pasture is the result. The natural herbage containing quantities of the natural salts —perhaps gathered from all parts of the soil and subsoil by long and persistent roots —is made to return these by burning, and they are thus in a most convenient state for easy absorbtion by the young grass. The grass so grown w"ill also be of the best quality for cattle.

And now we have taken a rapid run over some of the more important points in Agricultural Chemistry. It is a science well worthy of the study of every m*n, and of the practical farmer in particular. Agriculture is based on scientific principles, and without a knowledge of these principles the practical part of the subject, as it too often is, is a mere mechanical routine. Our soil is good, our climate is good, and there is every reason why we should produce grain, both of good quality and in large quantities. There is every reason why our pasture, our sheep and our cattle should be of the very best class. As yet it is virgin soil that is being worked, our infelix arjcr needs but little troublecomparatively speaking—to cultivate it. An increase of population, and a cutting down of very large farms will, however, work chaDges, the struggle will be keener, and greater care and attention—as at Home—will' have to be exercised. All the devices for improving the quantity and quality of the produce of the soil will be brought into play, and the man who is wanting in a good scientific grounding will be sure to fall behind in the race. It is necessary lo know not only how to do a thing, how it acts, and consequently why uis done. The theory must be ever linked with the practice. "O fortunatos nimium, sua si bona norint, Agricolas, quibus ipsa, procul discord/bus armis, Fundit humo facilem victum justissima tellus."

" O only too happy husbandmen if they knew but their own advantages !—for whom in the absence of clashing arms the grateful earth pours forth an easy sustenance, a support." A beautiful eulogy from Virgil on the condition of agriculturists, but not always applicable. (Concluded,)