THE FERTILIZING VALUES OF FEEDINGSTUFFS 323 



Laws and Gilbert at Rothamsted ^ obtained tlie following 

 results : 



Although these results are not conclusive by any means, 

 yet it seems safe to assume that with fairly mature fattening 

 or work animals about 90 per cent of the nitrogen, 75 per 

 cent of the phosphorus, and 90 per cent of the potassium 

 may be recovered in the manure. In case of milch cows not 

 so much is recovered in the manure because some is excreted 

 in the milk. 



The proportion of the organic matter of the ration which 

 is recovered in the manure depends, of course, upon the 

 amount of the organic matter digested. Thus feeds which 

 are quite digestible will produce a manure low in organic 

 matter, while feeds which are less digestible will produce 

 more organic matter in the manure. Ordinarily about one- 

 fourth of the organic matter of the ration is recovered in the 

 manure. In experiments with steers by Mumford, Grindley, 

 Emmett, and Bull at the Illinois Station,^ 26.6 per cent of 

 the organic matter of the feed was recovered in the manure. 



1 Warington, " Chemistry of the Farm," p. 214. 



2 Unpublished data. 



