410 BOARD OF AGRICULTURE. 



or salts of ammonia, it is evident that the plant has profited 

 largely by the application of the manures. At the same 

 time, while I think that corn, in common with the other 

 cereal crops, is dependent upon a liberal supply of nitric acid 

 in the soil, I must not, in saying this, be supposed to advocate 

 its application artificially. I quite agree with Mr. Stewart 

 in thinking that mineral manures alone should be used, or 

 mineral manures with the addition of a small quantity of 

 nitrogen, so long as they enable the farmer to grow a hun- 

 dred bushels of corn, or even a much smaller crop than that, 

 per acre. 



The only difference between Mr. Stewart and myself is 

 this : I think that it is to the soil, rather than to the atmos- 

 phere, that we must look for the supply of nitrogen ; while 

 Mr. Stewart's view is, that the poverty of his soil does not 

 admit of so large a supply being yielded. 



This question can only be set at rest by the continuous 

 growth of corn under mineral manures alone ; and, even 

 under such circumstances, many years might elapse before 

 satisfactory conclusions could be drawn. I have more than 

 once, when writing upon American agriculture, pointed out 

 the immense advantage which United-States farmers possess 

 over ourselves and others who live in climates not suitable 

 for the growth of cereal crops. 



It is quite true that the United-States farmer is fully aware 

 of this advantage, and does not require to have it pointed 

 out by me ; but, at the same time, I may possibly, b}^ the 

 aid of science, help him to understand wh}^ it is that he can 

 grow a much larger crop of corn than he can of any of the 

 other grain-crops, and further, when his land is more or less 

 exhausted, why mineral manures will be more effectual when 

 applied to the corn than when applied to other grain-crops. 



At Rothamsted we are now engaged in writing upon the 

 subject of rain-water and drainage ; and in the " Journal of 

 the Royal Agricultural Society," now being printed, will be 

 found an account of the composition of rain-water passing 

 through an uncropped soil. 



I abstain from entering upon any question with regard to 

 the source of the nitrogen which we find in our drainage- 

 water, and will merely point out that it could not have been 

 obtained from the atmosphere by plants, as the soil was kept 

 free from vegetation. 



