SOILS AND FERTILIZERS 107 



contains a sufficient amount of the three elements to 

 be worth about $40 at the average price of the same 

 amount of these elements in commercial fertilizers : 

 the cow, 14 tons, worth $39; the sheep, 9 tons, worth 

 $45; the calf, 14 tons, worth $40; the pig, 18 tons, 

 worth $80; fowls, 4 tons, worth $68. Sheep manure 

 is more valuable because it is drier. 



Young animals furnish manure less rich in nutriment 

 than more mature ones. Fowls yield the richest ma- 

 nure on the farm, but as said before, the quality of all 

 manure depends largely upon the quality of the food. 



Note. It has been computed that about 2 tons an acre each 

 year is enough manure for ordinary crops. One cow or horse or its 

 equivalent for each 5^ acres of land will furnish the required amount 

 of manure. 1 



Uses. - Animal manure is rich in plant food, es- 

 pecially the nitrogenous compounds, hence it enriches 

 the soil by the addition of nitrogen as well as phos- 

 phorus and potassium. But it does even more. It 

 favors the development of nitrate-forming bacteria 

 in the soil, and also changes the potash, lime, and 

 phosphorus of the soil into more soluble forms. 



Note. By the decay of organic matter organic acids are formed. 

 These acids - carbonic, humic, and nitric act upon insoluble com- 

 pounds of potassium and phosphorus and make them soluble. Thus 

 animal manure and green manure by their decay render plant food 

 available. 



As liquid manure contains the plant food in available 

 form for the plant to use, it is especially valuable as 

 a fertilizer. Manure, through its adding humus to the 

 soil, also renders the soil more capable of holding 

 moisture. 



1 Roberts, Fertility of the Land. 



