96 llUAV CROPS FEED. 



eompositiou of standard crop;^, and with the (][uantity con- 

 tained in appropriate applications of nitrogenous fertil- 

 izers. 



The average atmosplieric supply of nutritive nitrogen 

 in rain, etc., for 12 months, as above given, is much less 

 tlian is necessary for ordinary crops. According to Dr. 

 Anderson, the nitrogen in a crop of 28 bushels of wheat 

 and 1 (long) ton 3 cwt. of straw, is 45^^ lbs.; that in 2^ 

 tons of meadow hay is 50 lbs. The nitrogen in a crop of 

 clover hay of 2^ (long) tons is no less than 108 lbs. Ob- 

 viously, therefore, the atmospheric waters alone are in- 

 capable of furnishing crops with the quantity of nitrogen 

 they require. 



On the other hand, the atmospheric supply of nitrogen 

 hy rain, etc., is not inconsiderable, compared with the 

 amount of nitrogen, which often forms an effective manur- 

 ing. Peruvian guano and nitrate of soda (Chili saltpeter) 

 each contain about 15 percent of nitrogen. The nitrogen 

 of rain, estimated by the average above given, viz., 8f lbs., 

 corresponds to 58 lbs. of these fertilizers. 200 lbs. of gua- 

 no is for most field purposes a sufficient application, and 

 400 lbs. is a large manuring. In Great Britain, where ni- 

 trate of soda is largely employed as a fertilizer, 112 lbs. 

 of this substance is au ordinary dressing, which has been 

 known to double the grass crop. 



We notice, however, that the amount of nitrogen sup- 

 plied in the atmospheric waters is quite variable, as well 

 for ditferent localities as for different years, and for differ- 

 ent periods of the year. At Kuschen, but 2-2^ lbs. were 

 brought down against 21 lbs. at Proskau. At Regenwalde 

 the quantity was 15 lbs. in 1864-5, but the next year it 

 was nearly 30 per cent less. In 1855, at Rothamstead, 

 the greatest rain supply of nitrogen was in July, amount- 

 ing to 1^ lbs., and in October nearly as much more was 

 brought down; the least fell in January. In 1856 the 

 largest amount, 2^ lbs., fell in May; the next, 1 lb., ia 



