CREDIT FOR CALVES AND MANURE 49 



mary of studies in the manurial value of excreta of milch cows 

 by Sweeter 1 shows the relation of feeding to manure value: 



1. "The feces from milch cows contains J of the nitrogen, f of 

 the phosphoric acid, and J of the potash of the food. 



2. "The urine contains 5 of the nitrogen, almost no phosphoric 

 acid, and | of the potash of the food. 



3. "The milk contains less than g of the nitrogen, i of the phos- 

 phoric acid, and j\ of the potash, or less than | of the manurial 

 value of the food. 



4. "When the urine is allowed to waste, more than J of the 

 food, or 63 per cent of the manurial value of the soKd and liquid 

 manure is lost." 



Another method is to compute the value of manure on a 

 basis of increase in the value of crops. In farm management 

 studies by the U.S. Department of Agriculture ^ this plan is 

 being followed. The average value of the crops, corn, pota- 

 toes, wheat, oats, and hay on well-stocked farms in Pennsyl- 

 vania is given as $15.80 per animal unit more than on similar 

 farms with few animals. The animal unit, however, includes 

 animals other than dairy cows, which supply more fertiUty 

 than any other domestic animals. In similar studies in Mich- 

 igan the corresponding figure has been estimated as $8.22. 

 The difference is accounted for by the greater need for mineral 

 matter in the Pennsylvania soil and by the better care given 

 manure in Pennsylvania because of its higher value. This 

 difference shows that the value depends upon conditions and 

 needs of the soil of the dairy farm, and must to a large extent 

 be calculated with respect to each particular case. The in- 

 crease in crop value, however, usually is underestimated when 

 long periods of time are considered. Under conditions where 

 cows are well supplied with concentrated feeds and where the 

 manure is properly cared for, a cow of 1,000 pounds weight 

 will furnish $20 worth of added fertility per year. The prac- 

 tice in England,' which is covered by a law affecting landlord 



' Penna. Agr. Exp. Sta., Bull. No. 54, p. 7. 

 2 U. S. Dept. of Agr., Professional Papers, Bull. No. 341, p. 96. 

 ' Jour. Royal Agr. Soc, 193, Reported in Jan., 1915. Jour. Board of Agr., 

 pp. 931-934. Also " Feeds and Feeding," Henry and Morrison, p. 277. 



