116 BOARD OF AGRICULTURE. 



0.57 millionth parts of nitric acid in the rain, and during the 

 same month, after a thunder-storm, 9.8 millionths parts, or 

 17.5 times more than before. 



The same distinguished investigator noticed, also, from 1 

 to 2 millionth of ammonia as the usual amount in the rain, 

 and from 1 millionth to nothing in the snow. 



Of particular interest here are the results obtained by five 

 German experimental agricultural stations (Kuschen, Regen- 

 walde, Dahme, Insterburg, Ida-Marieuhlitte), during the 

 years of 1864, 1865 and 1866. The results obtained varied 

 in regard to the relative proportion of ammonia to nitric acid, 

 from 2.29 of the former to 0.46 of the latter, and again at 

 times from 1.16 of the latter to 0.67 of the former. 



The absolute annual amount of nitrogen obtained in both 

 forms was found fluctuating per acre from 2.0 to 14.89 

 pounds. 



The annual rain-fall in the various localities had been as 

 high as 26.7 P. inches; and as low as 15.5 inches. The 

 larojest amount of nitroo;en was noticed in the case of the most 

 copious annual rain-fall : the periodical distribution of nitro- 

 gen corresponded with the relative proportion of the rain- 

 fall. The mean of the annual supply of nitrogen plant-food 

 was 8.7 pounds per acre. 



Comparing the quantity of nitrogen contained in our best 

 commercial nitrogenous fertilizers with the largest annual 

 yield of atmospheric nitrogen plant-food, namely, that noticed 

 in the midst of Paris, we find it equal to that contained in 150 

 jDounds of potash-nitre, 140 pounds of Chili saltpetre, 110 

 pounds of sulphate of ammonia, 130 pounds of Chincha gu- 

 ano, 4,200 pounds of half-rotten stable manure. 



In the case of the smallest annual yield of but 2.0 pounds 

 per acre, it would be equal to that quantity of nitrogen which 

 we buy in 10 pounds of sulphate of ammonia, 12.5 pounds of 

 Chili saltpetre, 12.5 pounds of Chincha guano, 15.5 pounds 

 of potash-nitre, and 400 pounds of half-rotten stable manure. 



Nobody familiar with the amount of nitrogen carried off in 

 our ordinary farm crops, would hesitate for a moment to pro- 

 nounce the available amount of atmospheric nitrogen plant- 

 food, obtained by rain-fall, as previously illustrated, as insuf- 

 ficient in quantity. 



