3 6 



of manuring experimented with. On the other hand, 

 where minerals were supplied with nitrogen, the quality of 

 the grain, as indicated by the weight per bushel, was a good 

 deal higher than that of the unmanured plots. 



It is, however, with the comparison afforded between 

 ammonia salts and nitrate of soda that we are at present 

 most concerned. It must be remembered that these two 

 manures were used so as to supply the same amount of 

 nitrogen to the crop, not in equal weights of the manures 

 themselves. Thus, 400 Ibs. per acre of ammonia salts 

 were compared with 550 Ibs. per acre of nitrate of soda. 

 This must be clearly remembered, as it is important in 

 drawing conclusions from the experiments as to the relative 

 economy of different manures. In all experiments to be 

 -quoted comparing the action of sulphate and nitrate, the 

 same quantity of nitrogen was applied per acre in the two 

 forms, except where it is distinctly stated that equal weights 

 of the manures were used. 



In the Rothamsted experiments, nitrate of soda gave the 

 larger increase ; but the weight per bushel of the corn was 

 distinctly lower than that produced by ammonia salts, 

 whether the manures were used alone or with minerals. 

 The proportion of grain to straw is also worth noticing, 

 :for generally a crop giving a large proportion of straw is 

 more liable to be laid before harvest, and in many seasons 

 to suffer from blight. Averaging the two plots dressed 

 with ammonia salts, there was ill Ibs. of straw to each 

 _ioo Ibs. of grain ; but with nitrate of soda, there was on 

 -the average 210 Ibs. of straw to each 100 Ibs. of grain. 



In the experiments carried out at Woburn on continu- 

 ous wheat growing, similar results were obtained on the 

 average of twenty years. The following was the return 

 per acre per annum with the manures mentioned : 

 TABLE XV. 



* Nitrogenous manures applied in alternate years. 



