28 



RESULTS OF EXPERIMENTS AT ROTHAMSTED, 



dry) of the plot which had been entirely unmanured during the 32 

 years of the experiments with the Beans, contained 0-0993 per cent, of 

 nitrogen, that of the mineral manured plot 0-1087 per cent., and that 

 of the plot which had received both the mineral and nitrogenous 

 manure 0-1163 per cent., amounts which show considerable nitrogen 

 exhaustion of the surface-soil. 



Also in 1883, the nitrogen as nitric acid was determined in samples, 

 each of 9 inches of depth, down to a total depth of 72 inches. In the 

 case of several plots, the results show, calculated per acre, that the 

 total amount of nitrogen as nitric acid to the depth of 8 times 9 inches, 

 or 72 inches in all, was 27'95 Ibs. in the unmanured plot, 20-72 in that 

 with purely mineral manure, and 25-38 Ibs. in that of the plot which 

 had received both mineral and nitrogenous manure. In the soil of the 

 farm-yard manure plot, on the other hand, the amount was about twice 

 as much namely 50*46 Ibs. Excluding this last result, it may be said 

 that the amounts of nitrogen already existing as nitric acid, to the 

 depth determined, were very small. 



These, then, were the conditions of the soil when the Barley and 

 Clover were sown in the spring of 1883. The Clover grew very 

 luxuriantly from the first, so much so as considerably to interfere with 

 the growth of the Barley. 



Table XIII. (below), shows the amounts of nitrogen per acre in the 

 Barley and Clover in 1883, and in the Clover in 1884 and 1885. 



TABLE XIII. 

 BARLEY AND CLOVER, GROWN AFTER BEANS. 



Geescroft Field. 

 Nitrogen removed per acre in the Crops. 



It should be stated that the plots, the yield of nitrogen of which 

 is here given, do not exactly correspond with those for which the yield 

 of nitrogen in the Beans was given ; some of the Barley and Clover 

 crops having been taken together where no difference in the produce 

 was observable. Thus, half the plot represented as without manure, had 

 been unmanured from the commencement, that is for nearly 40 years, 

 but the other half received some nitrogen to 1878 inclusive, but had 

 since been entirely unmanured. Again, the results given in the second 

 line relate to the produce of a plot part of which received purely 

 mineral manure, but the other part ammonium-salts or nitrate up to 

 1878, but none since. The results given in the third line relate, 

 however, to a plot which has not received any nitrogenous manure 

 from the commencement of the experiments with the Beans, but which 



