202 



CROPS GROWN IX ROTATION 



8 bushels per acre. On the completely manm-ed plot a still 

 greater clover crop was obtained, 76*7 cwt. of hay; this in its 

 tui'n increased the total produce of the wheat crop from 4547 11 >. 

 to 5209 lb., or by 14 '6 per cent. The increase of gi-ain in this 

 case was 7 bushels per acre. 



Tm-ning now to the bean crojD 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 

 amomiting to 26 '9 per cent, on the unmanm-ed plot, 23 per 

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

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



Table LXIX. — Croijs f/'rown in rotation, Agclell Field. Effect of Clover {or 

 Beans) on the succeeding Surde and Barley CrojJS. Mean of four 

 Courses — Produce iKr acre. 



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 resom^ces 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 fom* courses 

 which have been completed, showing a comparison of the roots 

 and the barley after fallow and after clover (or beans) re- 



