Soil Fertility 71 



phosphorus, and .36 per cent potassium. Table I shows the 

 difference in the composition of manure from the several 

 classes of farm animals. It must be remembered in studying 

 the table that the percentages are for fresh manure and that 

 too often in the ordinary handling of manure not all the fer- 

 tility reaches the fields. 



Influence of age of animal on manure. A young animal, 

 since it requires large quantities of nitrogen, phosphorus, and 

 potassium in the building up of muscle and bone, takes more of 

 these elements from the food than does an older animal. As a 

 result, manure from young animals is less valuable pound 

 for pound than that from mature animals. 



Influence on manure of kind of work done by animal. How 

 the kind of work done by an animal influences the voidings can 

 well be illustrated in the case of cattle. A cow giving milk 

 takes out of her feed 24.5 per cent of the nitrogen it contains, 

 while a fattening ox that has already built up his lean-meat 

 tissues and frame requires only 3.9 per cent of the nitrogen of 

 the feed. 



Influence of feed on manure. Since an animal will retain 

 in its body only a portion of the fertility elements of its feed, 

 it is evident that when given a rich feed it will void a rich 

 manure. When a ration rich in protein is fed, a manure rich 

 in nitrogen will result. This has been proved by experiments 

 at several of the experiment stations. For example, Wheeler 

 found that when a nitrogenous ration was fed to hens, the 

 resulting manure analyzed : nitrogen .80 per cent ; phosphorus 

 .41 per cent ; potash .27 per cent ; and that when a car- 

 bonaceous ration (one poor in protein) was fed, the manure 

 showed : nitrogen .66 per cent ; phosphorus .32 per cent ; 

 potassium .21 per cent. 



Losses in manure due to improper handling. The method 

 of handling the manure has more to do with its composition 

 than any other factor. Loss can occur both by leaching and 

 by fermentation. Leaching, which means the dissolving out 



