334 
Journal of Agricultural Research 
Vol. VIII, No. 0 
winter. The concentration of the soil solution was higher in fallow soil 
than in that producing alfalfa, oats, or com, and nearly always greater 
in unirrigated than in irrigated soil. • It varied widely not only with the 
crop grown and the amount of water applied but also with depth of soil. 
There was always a larger amount of nitric nitrogen in fallow plants than 
in cropped ones, but when the quantity removed by the crop was con¬ 
sidered more nitric nitrogen was found in the cropped soil. The amount of 
nitric nitrogen was more constant in uncropped than in cropped plots 
and it was found to be comparatively constant in the lower sections of 
the soil, irrespective of the quantity of water supplied, up to 25 inches. 
Contrary to the results of Stewart and Greaves, Russell (12) found 
that during late summer and early autumn the nitrate content in fallow 
was higher than in cropped land, even after adding the nitrate taken up 
by the crop. In a semiarid soil Jensen (4) found no direct relationship 
between moisture and nitrates. He later (5) found that an irrigation, 
followed by a heavy rain, evidently diminished the nitrates. More ni¬ 
trates were found in summer-fallowed than in cropped soil. The average 
quantity of total nitrogen for the season showed no evident correlation 
with the quantity of nitrate nitrogen found. Control plots showed 
slightly more nitrates than those receiving either dry-yard or composted 
manure, but the reverse was true of the fallow plots. 
In a humid climate Weis (17) found no relationship between the per¬ 
centage of moisture and the nitrate production. King (7) found the 
same, and also that there is a lack of correlation between nitrates and 
crop yield. 
Watt (16), in South Africa, observed that manure, cultivation, and 
increased moisture served to raise the nitrate content. That manuring 
the soil with dung very slightly increased the amount of nitrates was 
among the observations of Tulaikov (15) in Russia. The depth to which 
regularly cultivated fallow land was plowed had little influence on the 
accumulation of nitrates. He also found that the accumulation of 
nitrates in the soil, under conditions obtaining in the black soil regions 
of Russia, was much facilitated by the fact that all measures taken'to 
accumulate water in the soil accelerated the accumulation. 
McIntyre (11), in reporting the results of 30 years' use of barnyard 
manure, concluded that soils receiving 6 and 10 tons of manure were 
practically identical in nitrate content, while the soil that received 8 
tons was lowest. 
At Cornell University the application of 20 tons of farm manure to the 
acre to sod on a clay loam soil for three years resulted in a larger produc¬ 
tion of nitrates on the manured soil than on adjoining unmanured soil. 
The work of Johansson (6) showed a close relation between the amount 
and movement of the soil water and the distribution of nitrates in a heavy 
clay soil. The nitrates were carried downward by the rain water and 
