Nitrification of Fertilizer and Mineralized Ammonium in No-Till and Plowed Soil1
- C. W. Rice and
- M. S. Smith2
The influence of tillage on nitrification was examined using a variety of assays of no-till and conventional tillage (plowed) soils. Ratios of NO-3 to NH+4 were higher in plowed soils except immediately after fertilization. However, concentrations of total inorganic soil N were about equal in the two tillage systems. Nitrification rates, following NH+4 additions to mixed sieved soils and to intact soil cores in the laboratory, were measured under various moisture regimes. Tillage did not consistently affect nitrification when soils of both tillage treatments were maintained at the same water content. Yet, nitrification was sensitive to soil moisture and since water evaporated more rapidly from plowed soils, nitrification was sometimes more rapid in no-till soils. One week after addition of 15NH+4 to field plots, more NH+4 had been converted to NO-3 in the no-till soil. It is suggested that nitrification of NH+4 fertilizer often will be more rapid in no-till soils because of more favorable moisture conditions. Without NH+4 additions, however, nitrifier substrate (NH+4) limitations may be more severe in no-till soils, causing slower or less complete NH+4 oxidation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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