27 



but little in the bean and clover crops, 1 as their annual produce 

 is only reduced by 382 Ibs. per acre where the turnips have 

 been carted. It is finally not shown by the wheat, the wheat 

 crops yielded by the plots where the roots were carted being 

 practically identical with those yielded where the roots were 

 fed. 



If we turn now to the division of the field receiving superphos- 

 phate, but no nitrogenous manure, we find not only the greater 

 diminution of the barley crop following the carting of the roots, 

 which we have already noticed, but we find that the other crops in 

 the rotation are also diminished to a small but sensible extent. 

 The carting, on an average, of 8 tons of swedes, with their 

 leaves, in each rotation, has apparently diminished the swede 

 crop on these plots by 1 ton 7 cwts. of roots ; has diminished 

 the bean and clover crops by 563 Ibs.; and has decreased the 

 wheat crop by 2^ bushels per acre. The carting of 8 tons of 

 swedes in this exhausted division of the field has thus been 

 attended with worse results than the carting of 16 tons on the 

 more liberally treated plots. We have before had examples 

 of the considerable results produced on poor land by small 

 residues of manure ; we now see another side of the same 

 fact, namely, the sensitiveness of poor land to any process of 

 exhaustion. 



We will now go a step further, and inquire what has been 

 the return in the various crops of the rotation for the large 

 amount of nitrogenous manure, equivalent to about 1 to 1 

 ton of cake per acre, applied to the swede crop in the upper 

 division of the field. In dealing with this question we will 

 take the average crops of eleven rotations, as in all of these 

 the nitrogenous manure was applied, although in one rotation 

 no roots were grown. The average results of these eleven 

 rotations will be found in Table IV. 



In order to estimate the practical effect of the nitrogenous 

 manure, we require to know what would have been the 

 produce of the land without its application ; to ascertain this 

 starting-point correctly is a difficulty which attends all trials 



1 In order to obtain one figure representing the leguminous crops in the 

 rotation, the total weight of the bean crops, corn and straw, and of the clover 

 crops weighed as hay, are summed together, and given as tons or pounds per 



