88 The Rothamsted Barley Experiments. 



roots carted off) ; 1848, barley ; 1849, clover ; 1850, wheat 

 1851, barley, with sulphate of ammonia. Having thus 

 grown two corn crops in succession, it was, agriculturally 

 speaking, in a somewhat exhausted condition for the after- 

 growth of grain, and would, in the course of ordinary 

 practice, be re-manured before growing another crop. It was, 

 therefore, in a suitable state for testing the effects of 

 different manures upon the crop, and for showing, by the 

 results, in what constituents, or class of constituents, the 

 soil had, by previous cropping, become practically the most 

 deficient. 



The area of 4J acres was divided into twenty-four nearly 

 square plots ; most of these were exactly one-fifth of an 

 acre each, but the remainder somewhat less. Two plots 

 were left unmanured, one was dressed every year with 

 farmyard manure, and others with different manures which, 

 respectively, supplied certain constituents of farmyard 

 manure, separately or in combination. The investigators 

 maintain that comparative results obtained in this way are 

 far better calculated to indicate in what constituent or 

 constituents the soil is relatively deficient, so far as the 

 available supply for the crop to be grown is concerned, than 

 what is generally understood as an analysis of the soil. 

 This, the synthetic, as distinguished from the analytic 

 method, is capable of giving important and conclusive 

 evidence as to the conditions and requirements of the 

 growth of barley, as indeed of other crops. 



The selection of manures for the experiments on barley 

 was, in many respects, the same as that adopted for those on 

 wheat. In reference to this point, Table XX. is instructive ; 

 it shows the probable average amounts of certain con- 

 stituents in what may be taken as fairly corresponding 

 crops of wheat and barley. The produce per acre assumed, 

 for this purpose, is : Wheat, 30 bushels of 601b. per bushel 

 =18001 b., and 30001b. straw=48001b. total produce ; Barley, 

 40 bushels of 521b. per bushel=20801b., and 25001b. straw 



