136 



LIVING ORGANISMS OF THE SOIL [chap. 



clover, down to a depth of 9 inches, was found to 

 contain 3915 lb. per acre of nitrogen, against 3540 lb. 

 after barley. Table XIII. sets out the figures. 

 Table XIII. — Effect of Growth of Clover on Succeeding Crop. 



Nitrogen in Crop and Soil. Lb. per Acre. 



Plot A. 



Plot B. 



In Crop (1873), Barley . . 37.3 

 In Soil after Barley . . 3540 

 In Crop (1874), Barley . . 39.1 



Clover . 

 After Clover 

 Barley . 



151-3 

 3915 

 69.4 



This last experiment illustrates a fact of great 

 practical importance — that a good crop of clover not 

 only produces a lot of highly nitrogenous fodder, in 

 which most of the nitrogen has been won from the air, 

 but also leaves behind in the roots and stubble such an 

 additional amount of nitrogen as will be of considerable 

 benefit to future crops. Another example from Rotham- 

 sted will illustrate this point : on the Agdell rotation 

 field, which is farmed on the Norfolk four-course shift, 

 one-half of the field carries no crop during the year pre- 

 ceding the wheat, whereas the other half grows clover or 

 beans. Thus an opportunity is afforded of estimating 

 the effect of the clover or beans on the succeeding crops 

 of the rotation. If we take for our example the years 

 following a specially good clover crop, and compare the 

 two plots which are manured once in the rotation, we 

 obtain the figures in table. 



Table XIV.— Total Produce per Acre after Clover or Bare 



Fallow. 



