214 



BOARD OF AGRICULTURE. 



fifteen per cent, of its weight of water. On increasing this pro- 

 portion, the straw in some cases was heavier, but the grain was 

 reduced in quantity. Thus the very fact that the amount of rain 

 fall is unequal in absolute quantity, and unequal in distribution 

 from year to year, is of itself a reason why you get different crops, 

 everything else remaining perfectly the same. That is a matter 

 always to be taken into consideration in judging of the value or effects 

 of a fertilizer. But it is the effect of nitrogen I am coming at. Dr. 

 Hellriegel experimented with various quantities of nitrogen (in 

 the form of nitrates,) applied also to cereals. The plants grew in 

 the artificial soil, consisting of pure sand, with an admixture of 

 ash ingredients, in such proportions as previous trials had demon- 

 strated to be appropriate. All the conditions of the experiments 

 were made as nearly alike as possible, except as regards the 

 amount of nitrogen, which in a series of eight trials ranged from 

 nothing to eighty-four parts in a million parts of soil. The 

 following table gives the result.* 

 Effect of Various Proportions of Assimilable Nitrogen in the Soil. 



The maximum crops of wheat and rye were obtained with 

 eighty-four parts of nitrogen to one million parts of this soil, but 

 the maximum oat crop was got with fifty-six parts of nitrogen ; at 

 least, the gain between fifty-six and eighty-four parts of nitrogen, 

 in the case of oats, was a mere trifle. Dr. Hellriegel made some 

 other observations, which he has not reported in detail, which led 

 him to conclude that he might have got his best crop of wheat 

 with seventy parts of nitrogen, his best crop of rye with sixty- 

 three parts, and his best crop of oats with fifty-six parts, to a 

 million parts of soil. This soil which he used was not a large 

 absorbent or fixer of the substances furnished to the plant. The 

 nitrogen which he used was in the form of nitrates, which are 



* See also " How Crops Feed," p. 288. 



