Ammonia Volatilization and Nitrogen Utilization from Sulfur-coated Ureas and Conventional Nitrogen Fertilizers1
- J. E. Matocha2
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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