284 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



cases, its chemical) action on the soil, and checks and controls 

 decomposition. The materials used for litter are not, as a rule, 

 rich in fertilizing ingredients. It is more important that all the 

 fertilizing ingredients of the manure should be preserved than 

 that its percentage composition should be increased or diminished. 



Straw is usually used for litter because it is one of the by- 

 products of the farm. It is a good absorbent, though rather poor 

 in fertilizing constituents. 



Leaves are good absorbents. 



Dry peat is an excellent material, as it has a high absorbing 

 power and contains fair amounts of nitrogen. 



Sawdust is a good absorbing material, but poor in fertilizing 

 constituents. 



The composition of some materials used as litter is as follows : x 

 POUNDS PER TON OF LITTER. 



Losses of Manure. All the plant food in the excreta of animals 

 cannot be saved. There are some unavoidable losses in nearly all 

 methods of collecting manure. The least loss of fertility occurs 

 when the animals are fed in the field to be manured, as the 

 excreta, solid and liquid particularly the liquids are then 

 absorbed by the soil. When manure is stored or preserved, there 

 is always a loss of plant food. The Rothamsted Experiment 

 Station estimates that, as a rule, under English conditions, one- 

 half of the nitrogen of the feed is lost, one-fourth of the phos- 

 phoric acid, and none of the potash. The chief causes of loss are 



(1) seepage, or penetration of the liquid manure into the soil; 



(2) weathering, or exposure to rain; (3) fermentation. 

 1 Beal, Farmers Bulletin No. 77. 



