CH. xj Litter 169 



But the richness of the urine also depends on the 

 animal. Fatting animals keep back very little of their 

 nitrogen only about 5 per cent. and pass most of it 

 out in the urine. Growing animals and milch cows keep 

 back considerably more, so that the urine is correspond- 

 ingly poorer. Consequently fatting animals make better 

 manure than young stock or dairy coivs. 



Since the urine contains most of the potash and more 

 than half of the nitrogen it must on no account be 

 allowed to waste: sufficient suitable litter must be 

 added to absorb it all. Straw, peat moss, and bracken 

 are used for the purpose; they not only absorb the urine 

 but also enrich the dung because they themselves con- 

 tain valuable fertilising materials. 



Straw is much the commonest form of litter: it 

 contains a fair amount of nitrogen and of potash, 

 it has considerable power of absorbing urine and it 

 encourages a biological fixation of ammonia. Its com- 

 position varies somewhat (Table IX), but on an average 

 one ton contains some 18s. worth of fertilising material. 



Table IX. Typical analyses of the materials used for 

 litter. 100 lbs. of each material contain: 



Nitrogen Phosphoric acid (P2O5) Potash (KjO) 

 Oat straw 0-50 0-24 1-00 



Wheat straw 0-45 0-24 0-80 



Barley straw 0-40 0-18 1-00 



Bracken 1-4 0-2 0-1 



Peatmoss 0-8 0-1 0-2 



Bracken compares very favourably with straw and 

 should be used whenever opportunity offers, especially 

 on heavy soils: on sandy soils, however, it suffers from 

 the drawback which, however, is not always very im- 

 portant that it decomposes more slowly. 



