THE MICRO-ORGANIC POPULATION OF THE SOIL 299 



Table LXXXI. — Nitrogen as Nitrate in Cropped and Uncropped Soils, 

 Ithaca, N.Y. (Lyon and Bizzell). Parts per Million. 



It is interesting to observe that the figures are generally of 

 the same order as at Rothamsted excepting only in July and 

 August, 1908. We have never observed, however, any in- 

 crease in nitrate on cropped land such as is recorded in their 

 maize experiments ; our results with wheat and barley have 

 always shown a decrease, like theirs with oats. Leather's 

 experiments in India {i6yb) and Prescott's in Egypt (228) 

 also show a decrease. The nitrate in the drainage water 

 from the fallow gauges at Pusa contained respectively 261-5 

 and 209-6 lb. per acre during the period 1907-9, while that in 

 the drainage water and crops of the gauges cropped with grass 

 accounted only for 128 4 and 1 1 5*6 lb. per acre over the same 

 period. The final rainfall before the account was made up was 

 so heavy as to deplete the gauges of nitrate, so that no error 

 arises through the retention of nitrate in the soil. 



Deherain's experiments made at Grignon, near Paris (81^), 

 between 1892 and 1897, also showed much more nitrate 

 coming from the fallow lysimeters than from those covered 

 with crops, even after allowing for what was absorbed by the 

 crop. In this case, however, it is uncertain how much nitrate 

 was left in the soil, the rainfall probably being insufficient to 

 wash it all out. 



Thus it seems to be an established fact that less nitrate 

 usually accumulates in cropped land than in fallow land, even 

 after allowing for what is absorbed by the crop. The wide 

 range of climatic conditions under which the result is obtained 

 seems to preclude any assumption that it is due to the effect 



