72 THE CHEMISTEY OF THE FARM. 



if no cake were employed, by the use of 2 cwts. of super- 

 phosphate for the swedes. 



The loss of nitrogen is een to be more considerable 

 than the loss of phosphoric acid or potash. The figures 

 given are also certainly below the truth, as they take no 

 account either of loss of nitrogen in the manure, or of the 

 nitrates lost to the soil by drainage. 



If the losses of nitrogen in the stable and the manure 

 heap amount to one half of the original nitrogen in the 

 manure (a case which is by no means impossible), the 

 annual loss of nitrogen will be raised to 42 Ibs. per 

 acre. 



The average annual loss of nitrogen as nitrates by 

 drainage from the soil (calculated from the composition 

 of uncontaminated spring and well waters) is in England 

 not less than 7 ibs. per acre. On arable land the loss, 

 especially in wet seasons, will riiuch exceed this figure. 

 Much may be done by the farmer to diminish this loss. 

 The early sowing of mustard, turnips, rape, or rye on 

 stubbles which are to be followed by a spring- sown crop 

 is most desirable; the green crops thus obtained to be 

 fed, or ploughed in, before the spring sowing. In the 

 case of a bare fallow it has been found advantageous to 

 plant mustard early in August, and plough the crop in in 

 October before wheat sowing. By such methods the 

 nitrogen of the nitrates is converted into vegetable matter, 

 and preserved from loss by drainage. 



Against the losses of nitrogen we have enumerated we 

 have to place the amount annually supplied to the land 

 by the rainfall, say 4 5 Ibs. per acre; and also the un- 

 known and more considerable quantity absorbed as 

 ammonia from the atmosphere by soil and plant. Of 



