44 



The Rothamsted Wheat Experiments. 



two years, is wonderfully instructive. It shows that during 

 the sixteen alternate seasons in which plot 17 received 

 ammonia-salts, and the sixteen alternate seasons in which 

 plot 18 received that substance, the average produce was 

 30 bushels per acre, whilst during the alternate years, in 

 which the plots received minerals only, they yielded but 15f 

 bushels; or, in other words, only a fraction more than 

 plot 5, which received no ammonia-salts during the whole 

 period. It is estimated that the 4001b. of ammonia-salts 

 applied per acre contain 861b. of nitrogen, but the resources 



TABLE "VTL AMMONIA-SALTS COMPARED WITH MINERALS. 



of the soil were evidently competent to furnish the nitrogen 

 contained in 15 bushels of wheat and its straw, inasmuch as 

 plot 5, receiving no ammonia, gave that produce. In the 

 additional 15 bushels and its straw obtained by the application 

 of the ammonia-salts, certainly less than 261b. of nitrogen 

 are carried off, thus leaving 601b. of nitrogen per acre to be 

 accounted for. Although analysis proved that, in 1881, 

 the soil of plots 17 and 18 contained rather more total 

 nitrogen and nitrates than plot 5, still, to a depth of as much 

 as 27in. there was no evidence of the existence in the soil of 



