Rotation of Crops. 
607 
land of the constituents of the turnips should, therefore, more 
materially affect the condition of the soil for the growth of 
the succeeding crops. It was shown that the effect was 
very marked on the barley which immediately succeeded the 
roots. There was also somewhat less produce, both of clover 
and of beans, where the roots had been removed ; and now, 
in the case of the fourth crop — the wheat — there is still 
distinct effect. Thus, taking the fallow portions, there was an 
average of 30f bushels of wheat where the roots had been re- 
moved, and 31 J bushels where they were fed or retained on the 
land ; the corresponding amounts of total produce being 
5,348 lb. and 5,658 lb. Or, taking the produce on the bean 
and clover portions, there were 28^ bushels of grain where the 
roots had been removed, and 31f bushels where they had not 
been removed ; the corresponding amounts of total produce 
being 4,841 lb. and 5,307 lb. Lastly, with the mixed manure, 
including nitrogen, the average produce was, on the fallow 
portions, 31 1 bushels after the removal of the roots, but only 
30^ where they had not been removed ; the amounts of total 
produce being, however, 5,808 lb. and 5,883 lb. On the bean 
or clover portions, the results were 32|- bushels where the roots 
were carted, and 33^ bushels where they were not removed ; and 
the amounts of total produce were 5,847 and 5,932 lb. 
Reference to the average produce of the last two courses, 
the tenth and eleventh, the wheat years of which were of more 
than average productiveness, shows, in the case of the manured 
plots, moi’e striking difference in the amount of the fourth crop 
due to the removal or the retention on the land of the constitu- 
ents of the first crop — the roots. The roots of those courses were, 
however, more than average in amount. 
The results, both with superphosphate alone, and with the 
mixed manure, afford, therefore, distinct evidence of the effect 
of the removal or otherwise of the first crop of the course — 'the 
turnips — not only on the second and third crops, but on the 
fourth crop — the wheat — also. 
The next point is to illustrate the difference of effect on the 
other crops of the rotation, on the one hand of the growth and 
removal of the highly niti’ogenous leguminous crop, and on the 
other of fallowing which removes nothing ; and first as to the 
wheat, which we are now specially considering, and which 
immediately succeeds the leguminous crop or the fallow. 
A careful examination of the average results over the eight 
courses (second to ninth) will show that, both without manure, 
and with superphosphate alone, that is under conditions of ex- 
haustion, especially of available nitrogen, the wheat crops were 
s s 2 
