Agricultural.

Clutha Leader, Volume II, Issue 83, 10 February 1876, Page 7

Agricultural.

SPECIAL CHEMICAL RELATION OF MANXTRES TO CROPS. In order to determine what manures -are best adapted to any special crop it 3s necessary to acquire an approximate knowledge ef their chemical constitu•e'nts.

Four elements constitute the chief material , of all plants, but these are never applied in their pure elementary forms, but always in combination with •other elements. The four elements ■which predominate in both vegetable ;and animal substances are carbon, nitrogen, oxygen, and hydrogen. The carbon which exists in plants is 'chiefly derived by tbem from the atmosphere where it exists in combination with oxygen in the form of carbonic acid gas. This gas exists in the •atmosphere as an impurity, derived, -among other sources, largely from the •combustion of fuel and the respiration ♦of animals.

Nitrogen is appropriated by plants •principally in the form of ammonia, which exists abundantly in farm-yard •manures, especially in the urine of animals. .It is also derived in large quantities directly from the atmosphere, to •which it is imparted by the decomposition of animal and -vegetable substances. Ammonia is also a compound gas, but <is not observed as such, being readily •taken up by water and other liquids, or condensed into the pores of manj substances that are not "liquid, as various kinds of eartn, particularly in clay. One principal reason for the addition of muck to the common forms of barnyard manures in the compost heap, is that it may absorb and retain the ammonia given off by the decomposition of the manure, such as a sponge absorbs tand, retains water.

This compound gas-ammonia is composed of hydrogen and nitrogen, and unlike carbonic acid, is one of the lightest of gasses, carbonic acid being *one of the heaviest ; we have no evidence that there is any separation of -nitrogen and hydrogen when used by the plant, each seeming to be used, though in a different manner. Although oxygen exists in great abundance in both plants and manures, its value seems to lie more in its properties <of assisting the plant to readily appropriate other fertilising substances than in its direct use as a food for plants, they seeming to possess the faculty of Tetaining the carbon and setting the •oxygen free. The woody fibre of plants, or their -stems and stocks, as well as the starch and sugar which exists in the grain or •fruit which they produce, are the materials composed chiefly of carbon. The •nitrogenous material is chiefly found in that portion of the grain which is called :gluten, and is there associated with starch, from which it may readily be separated.

It is not difficult to distinguish these substances in either natural or artificial fertilisers, or in the different parts of the plants or animals which they contribute to form. It is a knowledge of the various relations and conditions of these substances which the farmer needs to attain, in order to prosecute his calling with, the greatest profit, and to the %est advantage, and which he may .attain to such an extent as to be of ■much value to him in the mutual adaptation of the fertilisers which are available for his use, and the crops which ihe wishes to cultivate, and this without the expenditure of the time and labor necessary to become an expert analytical chemist. — ' Prairie Farmer. 1