322 



THE AGRICULTUKAL NEWS. 



October 20. 1917. 



A paper in Ilie Journal of the Royal Agricul- 

 tural Society of Evgland, Vol. 77, 191.5, by E. J. 

 Russell, D.Sc, and E. H Richards, from which the 

 present article largely draws, deals with this subject 

 from the point of view of results of experiments during 

 the previous three years at Rothamsted and 

 ■Cambridge. 



The subject is of quite as much importance to 

 Tnodern agriculturists as it was to the ancients, 

 and to those of tropical countries as to those 

 in the temperate zone. For not only is farm- 

 yard manure the most widely used fertilizer, but the 

 •amount used much exceeds both in weight and value 

 that of all other fertilizers put together. In the 

 United Kingdom alone the weight of farm-yard 

 manure made use of in the year before the war was 

 estimated at -37,000,000 tons, valued at £11,000,000, 

 while the weight of all other fertilizers used was 

 1,10.5,000 tons, valued at £4,540,000. In most other 

 agricultural countries the proportion of farm-yard 

 to artificial manures used is probably still greater. 

 Seeing then that farm-yard manure is of such prime 

 importance in agricultural econoni}', it is evident that 

 waste of its most valuable constituents should be 

 minimized as much as possible. Unfortunately this is, 

 under ordinary conditions of making and storing, very 

 ■considerable. Investigation into the causes of this 

 wastage is by no means easy, for farm-yard manure 

 is variable in composition, and difficult to sample and 

 analyse satisfactorily, so as to obtain reliable con- 

 clusions. The problem is being definitely attacked 

 however, and some definite results have been reached. 



It must be remembered that, apart from litter, 

 straw, etc., added to it, what is known as farm-yard 

 manure is made up of two kinds of excretions; the 

 solid fi'ces, which is the undigested material that the 

 animal's alimentary canal has been unable to deal with; 

 and the urine, containing the digested material, after 

 it has been dissolved, assimilated, and passed out of 

 the animal's body. 



Now modern analyses have shown that the urine 

 contains a far greater percentage of the most valuable 

 fertilizers, nitrogen and potash, than the solid fiece.s: 

 and further that the nitrogen and potash of the urine 

 are of more fertilizing value than the same constituents 

 of the fk'ces, because the former are already dissolved, 

 and capable of immediate assimilation b}' plants. 



It is impossible, however, in making farm-yard 

 manure to collect all the urine; consequent on this are 

 iihe differences noted in analyses of farm-yard manures. 

 It has been demonstrate^, however, that the manure 



coming from animals well fed on oil cake is richer in 

 nitrogen and phosphates than that from animals 

 deprived of such nitrogenous food. 



Experiments at Rothamsted were planned for 

 the purpose of finding out how to preserve ihe best 

 elements in farm-yard manure. In the first place it 

 was demonstrated that amanure heap should becompact- 

 ed as a measure of precaution, because the loss of nitrogen 

 and phosuhates from a compacted heap, as compared 

 with that from a loose heap, shows that the expense of 

 compacting is quite justified. The common practice in 

 the West Indies of keeping the manure in the cattle 

 shed until wanted for use, is to be commended in this 

 connexion. The continual trampling of the cattle does 

 much towards effective compacting. 



The next series of experiments was to discover 

 whether sheltering of a manure heap from weather and 

 rain was of any benefit. Here the results showed that 

 between unexposed and exposed manure there was 

 a very great difference, emphasizing the necessity of 

 shelter for manure heaps. The conclusion drawn from 

 this series of experiments is that the provision of 

 shelter for the manure heap is very important, and 

 that serious losses arise when manure is exposed to the 

 weather. Compacting the heap only slightly diminishes 

 the losses: the only way of dealing with them is to 

 provide a shelter of some sort to the heap.* 



An objection to sheltering a manure heap is that 

 it tends to make the manure too dry, which is correct 

 to a certain extent, inasmuch as dryness tends to 

 encourage nitrate formation, which is not especially 

 desirable, and to discourage the decomposition of the 

 litter, which is eminently desirable. But to try and 

 add water to a sheltered heap only makes matters 

 worse; the loss of nitrogen only becomes more marked. 

 Direct field experiments show that the best course to 

 pursue is to shelter the manure heap, but to check the 

 tendency to become dry by keeping it as compact as 

 possible. 



Further experiments showed that manure retains 

 its fertilizing constituents best when it is: — 



a. Kept compact; 



b. Sufficiently moist, but not too wet; 



c. Under shelter, and not stirred up. 



Yet all these precautions only retard inevitable 

 loss. So the question is, can not the loss in the bene- 

 ficial constituents of manure be altogether avoided ;' 



Experiments designed to find out what processes 

 go on in a manure heap, and why losses arise, have to 



