Rotation of Crops. 
615 
and nitrogen, but even under these conditions, and in rotation, 
the produce was very small. 
Under each condition as to manuring, the produce of dry 
matter in the clover grown in rotation was more, and in some 
very much more, than in the beans so grown. Without manure, 
it averaged only about 1 ton per acre per annum ; with super- 
phosphate, in one case more than 2, and in the other more than 
2 1,- tons ; and in each with the full manure, including potash and 
nitrogen, more than 3 tons. 
Lastly, the average production of dry substance in the six 
crops of beans and two of clover taken together was — without 
manure only about | ton ; with superphosphate, in one case 
little more than 1 ton, and in the other rather more than 1 \ ton ; 
and, with the mixed manure, in both cases less than If ton. 
These amounts in the leguminous crops with the mixed manure 
were, however, greater than those obtained in the turnip crops, 
but less than those in either the barley or the wheat grown in 
rotation. The significance of the amounts grown in the legu- 
minous crops will, however, be the more clearly recognised 
when we come to consider the quantities of nitrogen in the 
different crops; and also the fact of the large proportion of the 
manurial constituents of the leguminous crops grown in rotation, 
that will generally be retained on the farm. 
The Dry Matter in the Wheat Crops . — The bottom division ot 
the Table (V.) shows the average amounts of dry substance in 
the wheat — grain, straw, and total produce — grown in rotation, 
and those obtained in the same years in another field under as 
far as possible parallel conditions as to manuring, but grown 
continuously ; that is, year after year on the same land. 
A glance at the figures shows that, both without manure 
and with superphosphate alone, the amount of dry matter pro- 
duced was, both in grain and straw, in each case considerably 
less than half as much in the crops grown continuously as in 
those grown in rotation ; and that, even with the mixed manure, 
supplying both mineral constituents and nitrogen, it was con- 
siderably less in the continuous than in the rotation crops. 
So far as the unmanured and the superphosphate crops are 
concerned, it is obvious that the growth year after year must be 
much more exhausting, both of nitrogen and of certain essential 
mineral constituents, in a condition of composition and of 
distribution within the soil and subsoil available to one parti- 
cular crop, than when the crop is grown in alternation with 
others, of different requirements, habits, and root-ranges. 
It has been explained that iu the case of the mixed manure 
rotation plots there was applied for the first crop of the course, 
