24 BULLETIN 858, U. S. DEPARTMENT OF AGRICULTURE. 



and was credited to the cows at the same price per ton as winter 

 manure. 



A method of crediting manure was sought which would give definite 

 figures on its fertilizing value, taking into consideration the manure 

 available for return to the land, the method by which it was handled, 

 and its constituents. It is believed that the system used is just and 

 applicable. If, however, on certain individual farms or in certain 

 localities the needs of the soil would not warrant the payment of 

 market prices for all or part of the fertilizing constituents in the 

 manure, adjustments should be made accordingly. 



DETERMINATION OF FERTILIZING CONSTITUENTS IN FEED AND MANURE. 



The amounts of nitrogen, phosphoric acid, and potash in the feed 

 consumed were determined by use of the average analyses * of the 

 actual feeds consumed. As the descriptions and, wherever possible, 

 the analyses, of the different feeds were recorded, it was possible to 

 approximate quite closely the actual amount of fertility the manure 

 contained. In this way all the nitrogen, phosphoric acid, and potash 

 contained in all the feed consumed by each herd in the winter six 

 months was computed. Of these fertilizing constituents 75 per cent 

 of the nitrogen, 70 per cent of the phosphoric acid, and 85 per cent 

 of the potash were taken as representing the amounts that would be 

 voided in the manure. These proportions are based on the results 

 of digestion trials conducted by the Illinois and Pennsylvania experi- 

 ment stations. 2 



The amount of nitrogen which, it was calculated, was returned in 

 the manure was about 5 per cent lower than the average of the results 

 of the two experiments, because the cows on which records were 

 kept were not, for the most part, fed so heavily as the experiment- 

 station cows and would naturally retain more of the nitrogen in their 

 bodies. The phosphoric acid allowed was practically an average of 

 the experiments, and the potash was about 2 per cent more, as it was 

 thought the Illinois cows, since the experiment was conducted in 

 June, excreted considerable potash through their skins, which would 

 not hold true to so great an extent for cows in the winter period. 



When the total manurial constituents in the feed had been deter- 

 mined for each herd they were credited to the cows in accordance 

 with the scores which had been given to the herds for the total manure 

 saved. Each dairy was scored on its efficiency in saving manure, 

 taking into account such factors as manure voided in the barn, 

 quantity of liquid lost in the barn, and length of time and method of 

 storing. The ingredients of the manure credited to each herd were 



1 Taken from " Feeds and Feeding," by Henry and Morrison. 



' See Hopkins, Soil Fertility and Permanent Agriculture, pp. 201-202. 



