Dissimilar Nitrifying Capacities of Soils in Relation to Losses of Applied Nitrogen
1960
Clark, Francis E. | Beard, William E. | Smith, Donald H.
Forty-one soil lots from arable fields were found to vary widely in their nitrifying capacities when given an initial treatment of 400 ppm. of urea N and then incubated under standard conditions in the laboratory. Mineral N deficits exceeding 25% of the N applied were noted for poorly buffered soils which accumulated NO₂⁻ during incubation and which were initially acid in reaction or could achieve acidity during the course of nitrification of the added urea. Nitrogen deficits following treatment with KNO₂ were directly linked to initial soil pH values; they occurred in acid but not in alkaline soil. Conversion of the added NO₂⁻ to NO₃⁻ did not change the reaction of initially alkaline soils nor was it accompanied by the development of any significant N deficit. The data are believed to support the hypothesis that the instability or reactivity of nitrous acid in soil is at times responsible for large losses of gaseous N from fully aerobic soils.
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