XIV. 



FOODS AND FEEDING 



309 



oat. straw (containing only 0*5 per cent of total nitrogen). With many 

 foods, it averages about 5 or 6 per cent of the total nitrogen in the 

 food. With phosphoric acid, the same investigators found that from 3 

 or 4 per cent (with bran, malt culms, etc.) to 19 or 20 per cent (with 

 maize, rice meal, barley straw, oat straw, etc.) of the total present in 

 the food, was retained by fattening oxen and sheep. With potash, the 

 corresponding figures were 0*3 or 0*4 per cent (with roots) to 3 or 4 

 per cent (with malt, maize, etc.). 



The Bothamsted experiments, as summarised by Warington, 1 

 yielded the following results : 



With the ash constituents the following were the results : 



Lawes and Gilbert 2 give the average manurial value per ton of the 

 common feeding stuffs, as deduced from experiments, assuming that 

 they are supplied to fattening sheep and oxen. 



Hall and Voelcker have recalculated this table, bringing the values 

 more up to date (1902). They assume that half the nitrogen, three- 

 quarters of the phosphoric acid, and all the potash of the foods supplied 

 are voided in' the excrement, that each year after the application of 

 the dung, half its original value remains in the land and that nitrogen 

 is worth 12s. per unit, phosphorus pentoxide 3s. per unit, and potash 

 4s. per unit. The table on the next page then shows the compensation 

 value for each ton of the commoner foodstuffs consumed on the farm. 



1 Chemistry of the Farm, 162. 



2 Jour. Eoy. Agric. Soc., 1885, 600. 



