EELATION OF FOOD TO MANURE. 115 



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 richer manure than the cereal grains, while meadow hay 

 stands below them. The cereal grains and the roots con- 

 tain about the same proportion of nitrogen in their dry 

 substance; the roots, however, supply much more potash. 

 Potatos stand below roots in manurial value. Straw takes 

 the lowest place as a manure -yielding food ; bean and pea 

 straw are more valuable for this purpose than the straw of 

 the cereals. 



The ash constituents present in animal manure have 

 probably the full money value of the same constituents in 

 artificial manures, but the nitrogen has on the whole a 

 lower value than the nitrogen of ammonium salts or nitrate 

 of sodium. The nitrogen of the urine is indeed quite as 

 valuable as the nitrogen of ammonium salts. When 

 applied to soil the nitrogen of urine is rapidly converted 

 into nitrates, the form of nitrogen most suitable for plant 

 nourishment. But, on the other hand, the nitrogen of 

 the solid excrements is not in a form suitable for plant 

 food, and will be very slowly converted into nitrates in 

 the soil. 



Animal manure is probably more immediately available 

 for the use of plants when applied directly to the land, 

 than when previously mixed with a great bulk of litter. 

 Fermentation with litter probably results in the formation 

 of nitrogenous humus compounds, which are insoluble, 

 and decompose but slowly in the soil. 



The feeding of animals on the land is a mode of applying 



I 2 



