293 
Rotation Experiments. 
Sheep were put on to eat off the swedes on each of the four 
plots, the quantity consumed being kept down to 12 tons per 
acre, together with a little clover hay chaff ; the remainder of 
the roots were carted to the homestead. This rotation now 
coming into regular order (in 1906), the plan as arranged 
was commenced, the object being to ascertain the residual 
or unexhausted manure value of, on the one hand, a highly 
nitrogenous food like decorticated cotton cake, and, on the 
other hand, a starchy and low-nitrogen food like maize. 
The question at issue was whether, after giving these foods 
to sheep feeding off a root crop on the land, the manurial values, 
or the differences between them, of the two foods, as set out 
in Lawes and Gilbert’s Tables (or subsequent modifications 
of them), were justified in the crops subsequently grown as 
the result of the feeding of the cake or corn on the land. If 
compensation is to be paid, on the basis of the Tables, for the 
cake or corn so used, but the crop-producing (or unexhausted 
manurial) value of which has not yet been realised, it should 
clearly bear some relation to the increased crops which are 
capable of being grown thereby. It was, therefore, to see 
whether the crops so grown in an ordinary rotation course 
bore out, by their larger return, the money values assigned in 
the Tables, that this experiment in its new form was instituted. 
It is necessary here to go back shortly to the earlier history 
of these rotation experiments, for the same question presented 
itself at their first inception in 1876. After a number of 
years of experimenting under the four-course rotation of 
roots, barley, clover, wheat, it was ascertained that the influence 
of the clover crop (and this crop could, it was found, be grown 
on the Woburn land every fourth year without difficulty) was 
so great on the wheat and subsequent crops as to neutralise 
altogether any ’differences between the manurial value of the 
highly nitrogenous decorticated cotton cake and that of 
the low-nitrogen maize meal. It seldom happens, however, 
in practice that one can take a clover crop once in four years 
on the same land ; and, accordingly, it was now decided that 
if the question of manurial value were to be brought out, it 
must be by a course of cropping in which a clover or other 
leguminous crop was omitted, for the leguminous crops of the 
farm, it is now known (through the researches of Hellriegel), 
utilise the nitrogen of the atmosphere and store up nitrogen 
in the soil, thus practically supplying a nitrogenous manuring 
sufficient to neutralise the difference of effects capable of 
being produced by the use of such foods as decorticated 
cotton cake and maize meal when brought into comparison. 
Accordingly, in the new scheme now determined upon, it 
was resolved to omit the leguminous (clover) crop altogether, 
