144 



The Rothamsted Grass Experiments. 



machine, and by the subtler methods of the chemist and the 

 botanist, are all important. These we proceed to discuss. 



1. Without Manure : Plots 3 and 12. Table XXX., record- 

 ing the results on this plot, speaks for itself. 



TABLE XXX. AVERAGE PER ACRE PER ANNUM, WITHOUT MANURE. 



Average per Acre per Annum. 



The uniform superiority of plot 12 over plot 3 will not 

 escape notice. This was, at first, attributed to the fact that 

 plot 12 is earlier sheltered from the evening sun, and there- 

 fore the less liable to suffer in dry weather. But the 

 investigators were not content with this apparent reason, and 

 therefore sampled the soil of the plots, in each case to a 

 total depth of 54in., and from observations on the sections 

 dug up, as well as from estimations of the nitrogen in every 

 9in. of depth, were led to conclude that a considerable part, 

 at any rate, of plot 12 must have been made ground. 

 Accordingly, it was decided that the results obtained on the 

 unmanured plot 3 would provide fairer standards with which 

 to compare those yielded on the manured plots than would 



