Fate of the Nitrogen of the Soil 109 



ammonia. The increase in the produce of nitrogen by 

 farmyard manure is also calculated over that by the purely 

 mineral manure. An inspection of the table will show that 

 when the more excessive amounts of ammonia-salts were 

 applied for wheat, notably less than one-third of the supplied 

 nitrogen was recovered, and the less the greater the excess. 

 The general result is that with neither crop is the whole of 

 the supplied nitrogen recovered in the increase of produce 

 obtained; that when a given amount of ammonia-salts 

 was applied, a much less proportion was recovered in wheat 

 than in either barley or oats ; but that, even with wheat ? 

 more was recovered when nitrate of soda was employed 

 than when ammonia-salts were used. The nitrogen applied 

 in the manure, but not recovered in the increase of crop, 

 may be lost either by passing away in the drainage waters, 

 or by accumulating within the soil in a state of combination 

 or distribution unfavourable for being taken up by the 

 immediately succeeding crop. The facts elucidated by this 

 section of the investigation may now be briefly summarised. 



When either ammonia-salts, or nitrate of soda, or nitro- 

 genous organic manure in the form of rape-cake, or farm- 

 yard manure, was applied for either wheat or barley, a 

 considerable proportion of the nitrogen so supplied remained 

 unrecovered in the increase of the crop for which the 

 manure was employed; nor was the whole recovered in 

 many succeeding crops. When ammonia-salts were applied 

 in the autumn for wheat, a much less percentage of their 

 nitrogen was recovered in the increase of crop, than when 

 they were applied in the spring for barley or for oats. 

 Analyses of the soils to the depth of 27in. revealed a 

 considerable accumulation, within that depth, of the nitrogen 

 of manure which had not been recovered in the increase of 

 the crop ; but indicated that a still larger amount remained to 

 be otherwise accounted for. Analyses of the drainage waters 

 showed that they contained a large amount of nitrogen as 

 nitrates ; that the quantity of nitrates in the drainage was 



