LOSSES DURINa KOTATIOK 99 



The loss of nitrogen is seen 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 nitrogen voided by 

 the animals (a case which is by no means improbable), 

 the annual loss of nitrogen will be raised to 42 lbs. 

 per acre. 



The average annual loss of nitrogen as nitrates by 

 drainage from the soil (calculated from the composi- 

 tion of uncontaminated spring and well waters) is in 

 England not less than 7 lbs. per acre. On arable land 

 the loss, especially in wet seasons, will generally much 

 exceed this figure. 



Against the losses of nitrogen we have enumerated 

 we have to place the amount annually supplied to the 

 land by the rainfall — say, 4 lbs. per acre ; and also 

 the unknown and more considerable quantity absorbed 

 as ammonia from the atmosphere by soil and plant. 

 Of far greater importance is the supply of nitrogen 

 obtained by the cultivation of leguminous crops. 

 Where such crops can be successfully grown, and 

 are consumed upon the farm, there should be little 

 fear of a deterioration in the nitrogenous contents of 

 the soil under the conditions of rotation we have 

 supposed. 



In the four-course manured rotation upon the heavy 

 land at Eothamsted, consisting of swedes, barley, clover 

 or beans, and wheat, the nitrogen annually removed in 

 the crops, on an average of forty years, has exceeded 

 by about 32 lbs. the quantity supplied in the manure. 



