Ammonia Volatilization and Nitrogen Utilization from Sulfur-coated Ureas and Conventional Nitrogen Fertilizers
1976
Matocha, J. E.
Ammonia volatilization was measured on acid and calcareous soils receiving sulfur-coated ureas (SCU) and highly soluble N fertilizers. Surface and mixed applications of SCU-30 (30% dissolution rate), SCU-20 (20% dissolution rate), uncoated (NH₂)₂CO, NH₄NO₃, and (NH₄)₂SO₄ were made with and without lime to a fallowed acid fine sand. Without lime, top dressed NH₄NO₃, SCU-20, SCU-30, and (NH₄)₂SO₄ lost < 1% while (NH₂)₂CO lost 18.5% of added N in 14 days. Topdressing lime with N caused more NH₃ loss from (NH₄)₂SO₄ than from (NH₂)₂CO during the intial 48 hours. However, accumulative losses for 14 days were 51.5, 22.5, 9.0, and 1.7% from (NH₂)₂CO, (NH₄)₂SO₄, SCU-30, and SCU-20, respectively. Incorporating the lime with the soil prior to N addition reduced NH₃ loss > 50% as compared to surface application, but mixing N with the limed acid soil did not reduce NH₃-N losses. Mixing SCU with the soil appeared to increase release rate of N over topdressing, but this effect was not detected in plant response. Nitrogen uptake by corn (Zea mays L.) on the acid soil substantiated some of the conclusions regarding measured NH₃-N losses. Ammonia losses from N mixed with the finer textured calcareous clay loam were generally insignificant. Surface applied (NH₂)₂CO and (NH₄)₂SO₄ lost significant amounts of NH₃-N, while losses from SCU and NH₄NO₃ were negligible.
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