1920.] Farmyard Manure : Its Making and Use. 



447 



nitrogen. Assuming this latter figure were generally true — and 

 we have no reason for supposing otherwise — our 30 lb. of valuable 

 nitrogen would soon be reduced to little more than 10 lb. — i.e., 

 35 per cent, of the original nitrogen, or 75 per cr^nt. of the most 

 valuable portion, has disappeared. 



Loss in Farmyard Manure-— It has often been suggested that 

 kainit, gypsum, superphosphate, or other substance added to 

 the manure helps to reduce the loss by fixing ammonia. The 

 processes bringing about the loss, however, are too complex to 

 olfer any reasonable expectation of the discovery of a satisfactory 

 fixer. 



It is difficult to form any estimate of the loss which occurs to 

 farmyard manure over the whole country, but it must be consi- 

 derable. Taking the present consumption of straw in the farm 

 buildings of the United Kingdom to be about 10,000,000 tons per 

 annum, the production of farmyard manure would be 40,000,000 

 tons, worth at present prices some £25,000,000 or more. The 

 loss in making and storing the manure heap is not less, but pro- 

 bably more, than 20 per cent, of this, i.e., more than £5,000,000 

 each year. 



This loss cannot altogether be avoided, because it is part of 

 the cost of the necessary decomposition of the straw, but it can 

 be much reduced. In experiments at Eothamsted the provision 

 of shelter to keep off some of the rain much increased the eftec- 

 tiveness of the heap. 



Shelter can be provided in several ways. A layer of earth 

 has proved effective, but it is not always convenient. Straw- 

 thatched hurdles acted well in the trials. Placing the heap in a 

 well-sheltered position is also helpful. 



At present prices it is probably safe to suppose that an amount 

 from Is. to 5s. is added to the value of every ton of manure by 

 providing shelter. 



The Feeding" of Cake. — There has been considerable discussion 

 as to the extent to which cake-feeding adds to the value of farm- 

 yard manure. In; recent experiments the additional value due 

 to the cake was less than was expected, and the benefit of the 

 cake was shown only in the first year, and not afterwards. The 

 practical man, however, holds fast to cake-fed dung, and recent 

 experiments at Rothamsted have shown a direction in which it 

 may be superior to ordinary dung. The breaking up of the 

 litter to form hunnis is brought about by organisms which require 

 the sort of nitrogen compounds that they woukl find in cake -fed 



