48 PLANT PRODUCTS 



TABLE 7. NITROGEN HISTORY OF FEEDING. 



From which it \\ ill be seen that the effect of working a horse 

 is to increase the proportion of nitrogen that is excreted in 

 the liquid. The cow gives a higher proportion of nitrogen 

 as saleable products, and, in consequence, leaves less for 

 the manure heap. A calf fed on milk uses up most of the 

 nitrogen for its growth, and leaves but a small fraction for 

 manure. The average stock on a farm will vary according 

 to the system of management, but in no case will the pro- 

 portion of nitrogen sold be anything but small. The bulk 

 of the nitrogen that is eaten in the food goes back into the 

 manure, mostly in the soluble form and liable to loss by 

 drainage. The farm is, therefore, compelled to carry a very 

 big working capital in the form of nitrogen, from which the 

 annual return is comparatively small. 



A parallel table can be worked out for the potassium history. 



TABLE 8. POTASSIUM HISTORY OF FEEDING. 



Horse 



Fattening ox 

 Fattening sheep 

 Fattening pig 

 Milking cow 



