PLANT NUTRITION 



271 



kind ol animal, age and ration of the animal, kind and quantity ol 

 litter, and storage conditions. 



KIND OF ANIMAL. The nitrogen, phosphorus, and potassium con- 

 tents of manure vary with the species of animal from which it is 

 derived, as shown in Table 11-1. The composition of manure is af- 



TABLE 11-1. The Composition of Manure from Different Farm Animals 



as Based on 1-Ton Quantities 



(Data of Duley, Missouri Station Bulletin 166) 



Animal 



Weight of 



Manure, 



lb. 



Nitrogen, 

 lb. 



Phosphorus, 

 lb. 



Potassium, 

 lb. 



fected not only by the species but also by the utility of the animal. For 

 example, on maintenance rations steers may excrete in feces and urine 

 a quantity of mineral nutrients equal to that contained in the feed 

 ingested, whereas milch cows may utilize some of these elements for 

 the production of milk. It has been estimated that, for each 1,000 lb. of 

 milk, approximately 6 lb. of nitrogen, 2 lb. of phosphoric acid, and 2 

 lb. of potash are required. 



AGE OF THE ANIMAL. Growing animals excrete less of the fertilizing 

 constituents of their feed than do mature animals. A young growing 

 animal requires considerable quantities of calcium and phosphorus 

 as bone-building materials, and measurable quantities of these and 

 other constituents are retained for the synthesis of body tissues. 



