Feb. 26,1917 
Effect of Water and Manure in Nitrates in Soils 
343 
tons of manure reduced the moisture content of the cropped soil, and 
only slightly affected the nitrates, while 15 tons increased both the 
moisture and nitrates, especially for the larger applications of water. 
For 5 and 10 inches of irrigation water, when averaged for all manur- 
ings, the increase in moisture content due to irrigation was more rapid in 
the top few feet than below; but for 20 inches the increase was rather uni¬ 
form throughout the entire 10 feet. Although the nitrates were propor¬ 
tionately higher in the unirrigated plots at medium depths, the decrease 
in nitrates for increasing amounts of water was shown more in the top 
few feet than at the greater depths. 
In the fallow plots the highest percentage of moisture, on an average, 
was found under a manuring of 15 tons, and the least with no manure, 
but the differences were not great. The nitrates were also lower in the 
Man ure 
Applied 
Water 
Applied 
Fig. 8.—Graph showing the soil moisture and nitrates on July ai, 1913, to a depth of 10 feet in fallow soil to 
which different quantities of water and manure had been added. 
unmanured than in the manured land. The larger manuring was usually 
the more beneficial to the production of nitrates, especially in the unir¬ 
rigated land, although the 5-ton-per-acre plots contained somewhat 
larger amounts for 5 and 10 inches of water applied than the 15. The 
decrease in nitrates for increasing irrigations was rather marked. 
At this stage of growth practically the only difference in the moisture 
content between cropped and fallow plots is the greater loss on the 
cropped plots receiving no water, especially on the manured land. In a 
general way the nitrates of both cropped and fallow soils decrease with 
increasing amounts of irrigation water. The fallow plots show the 
effect of the increasing quantities of water more than do the cropped, 
and the influence is felt to greater depths in the fallow soils. 
The effect of cropping on nitrates was much greater for soils receiving 
manure, and especially where the amount of irrigation water applied 
