Influence of Moisture on the Effectiveness of Winter-Applied Nitrogen Fertilizers
1961
Kurtz, L. T. | Owens, L. D. | Hauck, R. D.
Two field experiments were conducted to compare the effectiveness of 3 forms of N when applied in the winter to a silt loam soil receiving 3 different rates of moisture. Ammonium sulfate, sodium or calcium nitrate, and urea were applied in the winter at the rates of 0, 60, 120, and 240 pounds of N per acre. The moisture rates ranging from 9 to 29 inches were established for the 5 months between fertilizer application and crop seeding. Four forage crops were then grown successively on the plots over a period of 2 years. Yield and nitrogen contents of the crops were determined for each plot. Nitrogen contents of crops from fertilized and unfertilized plots were, in general, inversely proportional to the amount of moisture applied to the plots during the winter and spring. Crop uptake of N from plots receiving ammonium, urea, and nitrate N was generally similar at lower moisture and N rates. However, uptake was less from nitrate-treated plots than from the corresponding ammonium-treated plots when applications of either N or moisture were increased to high levels. Experimental conditions were probably conductive to nitrogen losses through leaching and denitrification.
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