THE VALUE AND USE OF FARMYARD MANURE 



Dr. Jacob G. Lipman 

 Director, New Jersey Experiment Stations, Xew Brunswick, N. J. 



Farmyard manure differs from conmaercial fertilizers in that 

 it contains, apart from plant food, two constituents, the value of 

 which it is difBcnlt to gage. So far as the plant food itself is 

 concerned, we may compare it with equivalent materials in com- 

 mercial fertilizers. We know that a pound of nitrogen in nitrate 

 of soda or a pound of phosphoric acid in acid phosphate has a 

 definite value. What then is the value of these substances in 

 farmyard manure? Is a pound of nitrogen in the latter worth 

 as much as a pound of nitrogen in nitrate of soda ? Fortunately 

 for us we possess data that permits us to give a fairly accurate 

 answer to these questions. 



Numerous experiments in this coimtry and abroad have con- 

 clusively demonstrated that a pound of nitrogen in farmyard 

 manure is not worth as much as a pound of nitrogen in a pound 

 of nitrate of soda. They have demonstrated that under average 

 conditions as to climate, soil and crop, the increase from manure 

 nitrogen is only about half that from an equivalent quantity of 

 nitrate nitrogen. In other words the nitrogen in animal manures 

 is worth onlv half as much or less than nitrate nitrogen. If we 

 can buy the latter at eighteen cents per pound, the nitrogen in 

 manure should not be allowed a value greater than eight or nine 

 cents per pound. 



■Similarly, we have reason to conclude from facts in our pos- 

 session that the phosphoric acid in manure may be allowed a 

 value of three cents per pound and the potash about the same 

 value per pound. 



Now, taking for the sake of illustration, horse manure as con- 

 taining 0.5 per cent, of nitrogen, 0.4 per cent, of phosphoric acid, 

 and '0'.45 per cent, of potash, we find respectively ten, eight and 

 nine pounds per ton of these constituents. Hence the nitrogen 

 at nine cents per pound would be worth ninety cents; the 



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