WHAT FARMERS OUGHT TO KNOW.

Temuka Leader, Issue 1159, 1 April 1884, Page 3

WHAT FARMERS OUGHT TO KNOW.

AGRICULTURAL CHEMISTRY. ( Written specially for this Paper.) IX. We have now considered some of the more important mechanical means of improving land, and we now pass to the more important chemical ones. Under this heading comes the uses and chief properties of the various manures, and of these farmyard manure holds the first rank as being the most easily obtainable by the farmer and the manure which has the widest action. Farm yard manure contains the essentials of all the artificial manures and thus has a very wide range of use. The processes of digestion and the waste of tissue by exercise give rise to the solid and liquid excrements of animals. The flesh-forming materials already noticed are, after taking part in tha formation of flesh, unceasingly undergoing waste and decay ; this refuse matter, together, with the indigestible portion of the food, composes dung, which it will be seen must be made up of the same ultimate constituents as food. ‘So far from this matter being repulsive, as imagined by some fastidious persons, it displays to us, when viewed philosophically, the beautiful circle of operations necessary to the existence of animal and vegetable life.’ Of the two sorts of farm yard manure, liquid and solid, the liquid is richest in fertilising materials. The urine of animals contains many saline compounds, phosphoric acid, etc., and these of course are in a soluble condition, aud in the best possible condition for application to land. The fertilising influences of urine are in many cases overlooked, but the supposition that dung is superior to it is quite fallacious, for it must be remembered that the greater part of the solid excrements is composed of indigestible woody fibre, and is useless in the soil. The chief ingredients of the urine of the horse, cow, shsep, and pig, are : water, (between 800 and 900 parts in the 1000; organic matter (urea, uric acid, etc.) nitrogren (capable of yelding a considerable quantity of ammonia) salts of potash, soda, etc., and phosphoric acid. All these are exceedingly valuable fertilisers, and exist in a concentrated form, the more bulky solid dung containing but a small amount of valuable materials compared bulk for bulk with urine. The preservation of farm yard manure , is still a difficult task. When mixed with

good litter, the ammonia present in it has a tendency to volatilise. It exists chiefly as the oaroonate, which is very volatile at about 80 deg. F, In this way the ammonia is lost. One method of fixing ammonia has been already mentioned in these columns, namely by sprinkling the manors with dilute sulphuric acid, which of course ’converts carbonate of ammonia into the less volatile sulphate. When heaps are exposed to the atmosphere and rain, many of the soluble salts are lost by drainage, if suitable means of recovering and preserving it be not employed. In order to promote steady fermentation a certain heat is requisite. Fermentation—which is exactly the same chemical process as putrefaction—changes the condition of some of the constituents of manure by rendering insoluble ones soluble, and forming ammonia. salts that urine does not contain are found in dung ; nature thus evidently intends that the two should be used together, and the best method for keeping a manure heap moist is by constant application of the liquid excrements. A mixture of the two produces a ‘ general ’ manure and is able to supply all the requisite constituents of the food of plants, though, in particular cases not in the best possible proportions. By applying farm yard manure every component of plant food is added to and the general fertility of the soil increased, but should the soil be deficient in any particular compound, as lime, then a very large amount of this manure would have to be put on the land, and by so doing excess of other unnecessary matters would bo applied. In such a case this general fertiliser would not be the most economical. Strange to say, the management of dung has not been well understood until lately ; though it has been the great manure from time immemoiial, yet chemists have only recently discovered the changes this complex compound undergoes during fermentation. Speaking of this suffiect Mr Sibson, points out that a great deal is due to the exertions of Dr Voelcker who completed these investigations. He goes onto say : —‘ln the carrying out of this investigation in the laboratory of the Royal Agricultural College, I enjoy to the honor of having contributed a bumble part, and am therefore in a position to speak confidently and from personal experience on the facta adduced in the following description of the changes farm yard manure undergoes by keeping ; and it is hoped that this description may not be unworthy of the attention of practical men, who may, we think, gather from it hints that will be of service to them in the treatment of farm yard manure.’ This is his analysis of a mixture of horse, cow, and pig dung : In natural state. Water 66.17 Soluble organic matter ... ... 2-48 Soluble inorganic matter 1.54 Insoluble organic matter 25.57 Insoluble inorganic matter ... 4.05 moo Under the heading ‘ soluble inorganic matter ’ are included the following salts, etc., which, taken together, made up the 1.54 per cent. Soluble silica, phosphate of lime, lime, magnesia, potash, soda, chloride of sodium (common salt), sulphuric acid, carbonic acid, and loss. The nitrogen in the organic portions is calculated to be able to produce so much ammonia. The amount of ammonia afforded by all the nitrogen present was found to be .780 per cent. In this analysis it will be seen that a very large amount of insoluble matter is present, and it is due to this fact that fresh manure exerts little immediate benefit. Let us now see the analysis of well rotted dung, and after comparing it with the foregoing, the changes that takes place during fermentation will be apparent. This is the analysis of rotten dung six months old : Water ... ... ... ... 75.42 Soluble organic matter 3.71 Soluble inorganic matter (ash) ... 1.47 Insoluble organic matter 12.82 Insoluble inorganic matter ... 6.58 100.00 Under the heading ‘ soluble organic matter ’ the same compounds are included as in the preceding table. The detailed results of the analysis are not put down, as they would occupy a considerable amount of space. Now comparing the two analyses the following facts are evident : —(1). That there is more water present i n the rotted than in the fresh manure. (2), That there is more soluble organic matter after fermentation. (3). That on the whole there is little change in the quantity of soluble inorganic substances. The increase in soluble organic matter is chiefly in respect of nitrogen, which by decay yields ammonia. Though, in the above condensed analysis, there is little apparent change so far as soluble inorganic matter is concerned, still, on comparing the detailed results, we find that the more valuable fertilising salts increase in quantity in regard to solubility and an almost equal quaatity the less valuable salts becomes insoluble. Tims there is more soluble silica, phosphate of lime, lime, aud magnesia present in the rotted than in the natural state of the manure, and there is a corresponding diminished quantity of soluble potash, soda, chloride of sodium, sulphuric acid and carbonic acid. From these tacts we perceive how that farmyard manure is more efficient after it undergoes fermentation than before it. It is also then in a mere compact and better state for application. Fermentation always takes place more readily in warm than in cold weather, and a certain medium amount of moisture should always be maintained, too much wet, as where the heap is exposed to rain, stops the chemical changes altogether, and if too dry the operation is retarded. Fermentation or putrefaction is a chemical change which all animal and vegetable organisms undergo. It is a process by which complex organic compounds split up into various less complex ones, and these products are chiefly water, carbonic acid, and ammonia, all of which are volatile at a comparatively low temperature. These are the substances given off by fermenting dung, water and carbonic acid escape freely, but the ammonia, especially that present in the middle of the heap, unites with various organic acids in the manure, and in this way it becomes fixed, or unable to volatilise. In order that the ammonia should be preserved all stiring of the heap should de avoided ; the percolation of the

water, etc., through it will tend to keep it porous enough. The drainings from n heap are always carefully preserved, for more is lost in this way by the departure of soluble salts than by volatilisation. When this manure is applied to land after having rotted, the ammonia being fixed by the various acids ,little will be lost. Should the soil need organic matter the preferable course is to let the fresh dung ferment in the soil. (To he Continued.)