Long-Term Denitrification Studies in Soils Fertilized With (15NH4)2SO4
1978
Focht, D. D. | Stolzy, L. H.
A 2-year study was conducted in lysimeters containing four different soils with successive summer and winter crops of corn and barley, respectively. The crops were fertilized with (¹⁵NH₄)₂SO₄ at application rates equivalent to 134, 108, 415, and 440 Kg N/ha for the respective summer 1973, winter 1974, summer 1974, and winter 1975 crops. The frequency of ¹⁵N dinitrogen samples was higher in the summer and higher at the lower fertilizer rates, while the reverse was true for NO₃⁻ concentrations in leach water and N₂O concentrations in the soil profile. Emissions of N₂O from soil, even where the higher concentrations were observed, were low in terms of N losses with the greatest mass emission at any time amounting to 6.5 g/ha over a 1-day period. Nitrogen gas emissions over a 1-week period in one instance were estimated at 5.2 kg N/ha: it was observed that this amount could be generated from low (1 ppm or less) concentrations of N₂O.
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