328 SOILS AND MANURES 



these quantities in the form of artificial manures, it 

 would be necessary to employ, in round numbers, about 

 9 cwts. of nitrate of soda, 8 cwts. of kainite and 5 cwts. 

 of superphosphate. Apart from the question of expense, 

 it is obvious that such quantities could not be employed 

 without seriously deteriorating both the soil and the 

 crop to which they might be .applied. The quantity of 

 nitrate is about j^our times as much as is commonly applied 

 at one time ; if it were divided into four, and one part 

 applied each year, the allowance would be regarded as 

 liberal, and large returns might be expected. This, how- 

 ever, does not hold good equally for the phosphates and 

 kainite. 



It will thus be seen that an ordinary dressing of farm- 

 yard manure supplies large amounts of plant food, and 

 the manurial effects produced by it are attributable, in 

 great measure, to this fact. 



State of Combination. It is frequently claimed for 

 farmyard manure that it is both rapid in its action and 

 lasting in character. It can be applied in large quanti- 

 ties at a time without injury to the crops and with- 

 out much risk of loss of plant foods. It may be 

 assumed therefore that the state of combination in 

 which the fertilising ingredients, and particularly the 

 nitrogen, are present, is different from that of the nitrogen 

 in nitrate of soda or in the slower acting nitrogenous 

 manures, such as bone meal, etc. It is evident from 

 what has been said regarding the complex nature of the 

 materials of which the manure is composed, and the fer- 

 mentative changes which they undergo in the process of 

 making, that this is so. It is evident, in fact, that the 

 nitrogen in farmyard manure exists not in one, but in 

 several, perhaps in many, different forms. 



Part of the nitrogenous matter is soluble in water ; it 

 readily undergoes nitrification, and is immediately avail- 



