98 



THE ROTHAMSTED EXPERIMENTS. 



the barley under most conditions, it is considerably lower in 

 the better seasons. It may be observed that the exceptions 

 in the case of the barley were, where organic manure, as in 

 rape-cake and farmyard manure, was employed. 



TABLE 31. 



Season and 

 silica in 

 straw. 



Strength of 

 straw not 

 dependent 

 upon silica. 



Per cent 

 grain in 



total 

 produce. 



Weight per 



bushel of 



dressed 



grain. 



Per cent 



ash in 



dry 



matter. 



WHEAT. 



BARLEY. 



Rape-cake . 



Rape-cake . 



Mineral manure 

 and amm. -salts 



Mineral manure 

 and amm. -salts 



Farmyard man- 

 ure 



Farmyard man- 

 ure 



(1852 

 1 1871 



(1856 

 11863 



(1852 

 11871 



(1856 

 11863 



(1852 

 11871 



(1856 

 11863 



Per cent 



silica in 



ash. 



Per cent 

 silica in 



dry 

 matter. 



2.73 

 2.33 



2.29 

 2.36 



2.61 

 2.19 



3.15 

 2.23 



2.96 

 3.22 



2.85 

 2.68 



Direct analytical results clearly show, therefore, that the 

 proportion of silica is as a rule lower, not higher, in the 

 straw of the better grown and better ripened crops. 



This result is quite inconsistent with the usually accepted 

 view that high quality and stiffness of straw depend on a 

 high amount of silica. Pierre and Bretschneider have, 

 indeed, concluded from their experiments that this is not the 

 case, and at Rothamsted we have long maintained a contrary 

 view. In fact, high proportion of silica means a relatively 



