MANURE VALUE OF FOODS 219 



ManTire Value of Foods. — (1) Belative Value. The 

 relative value of the manure produced by different 

 foods is determined by the relative richness of the 

 foods in nitrogen and ash constituents, but chiefly by 

 the amount of nitrogen, this being the most costly 

 ingredient of purchased manure. The average amount 

 of nitrogen, and of the two most important ash con- 

 stituents contained in ordinary cattle foods, is shown 

 in the following table. The relative manure value of 

 each food has been calculated from the market prices 

 of the manure constituents ; these prices are, of course, 

 liable to variation.^ 



The manure value of different foods varies ex- 

 tremely. One ton of decorticated cotton cake has 

 about four times the manure value of a ton of wheat, 

 barley or oats, and thirty times as much as a ton of 

 turnips. The practical importance of such facts is very 

 great. We have already seen that decorticated cotton 

 cake and wheat may yield almost the same increase in 

 live weight when employed as food ; they may also 

 have the same price per ton. The farmer will, how- 

 ever, unhesitatingly prefer the cake in consequence of 

 its far higher manure value. 



The oilcakes yield the richest manure, as they 

 contain the largest amount of nitrogen and phosphoric 

 acid, with a considerable amount of potash . Next to 

 these come the leguminous seeds, malt dust and bran. 

 Clover hay yields a rather richer manure than the 

 cereal grains, while meadow hay stands rather below 



• In January, 1902, the wholesale price of nitrate of soda at Liver- 

 pool was £10 a ton ; of kainite, £2 10s. ; of 30 per cent, superphos- 

 phate, £2 12s. These prices work out to the following values : Nitrogen 

 nearly 7d. per lb., phosphoric acid, 2d., and potash, 2d. per lb. 



