216 THE ROTHAMSTED EXPERIMENTS. 



individual years, since the characters of the seasons may have 

 so much influence. But it may be observed that, after the 

 heavy crops of clover on the superphosphate plots in 1882, 

 and more where the roots were fed than where they had been 

 removed, the wheat crops of the next year, 1883, which were 

 higher than average, were lower after the leguminous crop 

 than after fallow ; whilst, on the highly manured plot, they 

 were much the higher after the leguminous crop. In the 

 tenth course, however, after the use of potash as well as 

 superphosphate, there were fair but by no means such heavy 

 crops of clover as in the very favourable season of the preced- 

 ing course, and there was less where there had then been the 

 larger crop ; and in the eleventh course also there was less 

 total produce of beans where the heavier crop of clover had 

 been grown in the ninth course. The result was, that on the 

 average of the last two courses the wheat gave less instead of 

 more total produce after fallow than after the leguminous 

 crops ; but more where the roots had been fed than where 

 they had been carted — that is, more where the land was the 

 less exhausted. 



The general result is, that where there was not exhaustion, 

 but accumulation due to manure and to increased crop 

 residue, the growth and removal of the leguminous crops not 

 only gave large amounts of nitrogen in the removed crops, 

 whilst the fallow yielded none, but also left more available 

 nitrogen for the succeeding wheat than was rendered available 

 (and remained) from the resources of the soil after the fallow. 

 In other words, not only were the nitrogen and other con- 

 stituents obtained in the leguminous crops an entire gain 

 compared with the result of fallow, but, on the average of 

 years, a somewhat larger succeeding wheat crop was obtained 

 as well. 



Here, then, is a striking illustration of the advantages of 

 the interpolation of leguminous crops instead of fallow with 

 the cereals in our rotations ; and it is seen that the benefit 

 may be the greater if the land be not abnormally exhausted, 

 as was the case on the continuously unmanured and on the 

 superphosphate plots. 



Although there was thus great difference between the 

 effects, on the one hand, of the growth and removal of a 

 leguminous crop, and on the other of fallow, so far as the 

 third year of the course is concerned ; yet, where the manurial 

 conditions were not defective, there was even more wheat 

 succeeding the leguminous crop than succeeding the fallow. 

 The influence of the conditions of the third year of the course 

 does not, however, seem to extend in any marked degree to 

 the crop succeeding the wheat — that is, to the roots com- 



