72 



The Rothamsted Wheat Experiments. 



Though it has long been known that an excess of rain is 

 injurious to the wheat crop, it is only within comparatively 

 recent years that one, at least, of the material causes of the 

 adverse influence has been clearly made out, namely, the great 

 loss of nitrogen carried off by drainage in the form of nitrates. 

 Moreover, when the manures are autumn-sown, this loss is 

 much greater during the winter than during the later period 

 of the season. Table XV. shows the bushels of grain and 

 the weight of straw, and of total produce, obtained in each of 

 the seven years, from 1873 to 1879 inclusive, by autumn sowing 

 and by spring sowing respectively, of the ammonia-salts. 



TABLE XV. AUTUMN SOWING AND SPRING SOWING OF 

 AMMONIA-SALTS. 



Only in 1874, therefore, was the result decidedly in favour 

 of autumn sowing. In 1873, 1877, 1878, and 1879 it was 

 decidedly against autumn sowing ; whilst in 1875 and 1876 

 the difference was immaterial. It is particularly worthy of 

 note that during the period between the autumn sowing and 

 the spring sowing the rainfall was far less in the season of 

 1874 than in any of the others. The season of 1875 ranks 

 next in this respect. 



