NITROGEN ACCUMULATED IN CLOVER CROPS 147 



TABLE LV. Continued. 



* See footnote, p. 146. 



Now even this latter amount corresponds to what would be 

 considered a fair, though not a large crop, when clover is grown 

 in rotation once only in four or eight years or more ; so that the 

 produce in the earlier years on this rich garden soil was very 

 unusually heavy. Indeed the average annual produce over the 

 period of fifty years namely, 5794 lb., or more than 2^ tons of 

 hay .would be a good yield for the crop grown only occasion- 

 ally in the ordinary course of agriculture. 



But it is when we look at the figures in the last column of 

 the table, which show the estimated amounts of nitrogen in the 

 crops, that the importance and significance of these results 

 obtained on rich garden soil are fully recognised ; and this is 

 especially the case when they are compared with those 

 obtained on ordinary arable land. 



Thus the amount of nitrogen in fair crops of wheat, barley, 

 or oats would be 40-50 lb. per acre, of beans about 100 lb., of 

 meadow hay about 50 lb., and of clover grown in rotation, from 

 100 to 150 lb. ; but on this rich garden soil the produce of 

 clover has in one year contained more than 400 lb. of nitrogen, 

 and the average over the first ten years was 247 lb. The 



