202 



CROPS GROWN IN ROTATION 



increased the total produce of the wheat crop from 5338 Ib. to 

 6292 Ib., or by 17'9 per cent., the extra grain amounting to 

 6 bushels per acre. On the completely manured plot a still 

 greater clover crop was obtained, 76 - 6 cwt. of hay; this in its 

 turn increased the total produce of the wheat crop from 5454 Ib. 

 to 6163 Ib., or by 13 per cent. The increase of grain in this 

 case was 5 bushels per acre. 



Turning now to the bean crop of 1862, the largest of the 

 series, we find that it was also followed by a specially good 

 wheat crop in 1863, but that in each case the wheat was less 

 after the beans than after the bare fallow, the diminution 

 amounting to 26 '9 per cent, on the unmanured plot, 23 per 



TABLE LXIX. Crops grown in rotation, Agdell Field. Effect of Clover (or 

 Beans) on the succeeding Swede and Barley Crops. Mean of six 

 Courses Produce per acre. 



cent, on the plot receiving superphosphate only, and 127 per 

 cent, on the completely manured plot. These results can only 

 be interpreted by supposing that the large bean crop, so far 

 from obtaining all the nitrogen it required from the atmosphere, 

 drew extensively upon the resources in the soil, consequently, 

 instead of enriching the land like the clover crop it actually left 

 it poorer than it was before 



Since the growth of clover has such a marked effect on 

 the subsequent crop of wheat, the question of the duration of 

 the benefit caused by the clover naturally arises. Table LXIX. 

 gives a summary of the results during the last six courses 



