212 THE EOTHAMSTED EXPERIMENTS. 



Legumin- As already referred to, in the second and subsequent 

 M*a«X«- courses, when the third year came round each plot was 

 tute for divided, clover or beans being grown on one half, and the 

 fallow. other lialf left f a now. We have, therefore, the means of com- 

 paring the effects on the other crops of the rotation — of fallow 

 on the one hand, which of course removes nothing (though 

 there may be the more loss by drainage), and of growing 

 beans or clover on the other, a characteristic of which is the 

 assimilation, and consequently the removal in the crops, 

 especially of large amounts of nitrogen, but of other consti- 

 tuents also ; at the same time, however, leaving in the land 

 more or less of nitrogenous crop-residue. Such a comparison 

 obviously has a special interest, since it is chiefly as a substi- 

 tute for fallow that the growth of leguminous crops has been 

 introduced into our rotations. 



The Wheat Crops. 



Table 59 (p. 213) records the results obtained with the 



fourth element of the rotation — the wheat — exactly in the 



same form as in the case of the other crops. 



Variations Looking first to the figures relating to the individual years, 



imth if. j s seen that under each condition of manuring or other 



seasons. ' , ° 



treatment, there is an enormous variation in the amount oi 

 produce in the different years, according to the seasons. Thus, 

 taking for illustration the results in the first column under 

 each of the three main conditions as to manuring, that is 

 where the roots were carted from the land, and where in the 

 third year of the course it was left fallow, there was, without 

 manure, only 10| bushels of wheat in 1879, but 45 bushels in 

 1863 ; on the superphosphate plot there was in 1879 only 14§ 

 bushels, and 46 bushels in 1863 ; and on the mixed manure 

 plot only 12f bushels in 1879, but 52| bushels in 1863. Or, 

 comparing the quantities of total produce, corn and straw to- 

 gether, which more directly represent the amounts of growth, 

 we have, on the same plots, without manure, 2162 lb. per acre 

 in 1879, and 7446 lb. in 1863 ; on the superphosphate plot 

 2905 lb. in 1879, and 7626 lb. in 1863 ; and lastly, on the 

 mixed manure plot, only 2478 lb. in 1879, but 8837 lb. in 

 1863. 



The cases cited are those of the most extreme fluctuations 

 due to season ; but a glance at the columns will show that 

 there were very considerable variations in other years, under 

 each condition as to manuring, or other treatment ; whilst 

 the amounts of the variations differ more or less under the 

 different soil conditions. It will be obvious, therefore, that 

 if we would fairly compare with one another the effects of 



