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Ammonia Volatilization from Surface Applications of Ammonium Compounds on Calcareous Soils: II. Effects of Temperature and Rate of Ammonium Nitrogen Application

Fenn, L. B., Kissel, D. E.
Soil Science Society of America journal 1974 v.38 no.4 pp. 606-610
ammonia, ammonium, ammonium carbonate, ammonium nitrate, ammonium nitrogen, ammonium sulfate, application rate, calcareous soils, calcium carbonate, carbon, clay, clay loam soils, equations, pH, stable isotopes, temperature, volatilization
The effects of temperature and rate of application on NH₃-N volatilization from NH₄⁺ salts applied to the surface of a calcareous soil were investigated in the laboratory. Total NH₃-N losses were only slightly influenced by temperature over a broad range of NH₄⁺-N application rates with a precipitate forming NH₄⁺ compound such as (NH₄)₂SO₄ in a calcareous soil. The rates of NH₃-N loss were highly influenced by temperature. High temperatures increased the initial rates of NH₃-N loss although they were proportionally reduced at later stages. The lowest temperature resulted in the lowest initial NH₃-N loss rate but became highest for the last 76 hours. Total ammonia nitrogen losses were dependent on the rate of NH₄⁺-N application. The quantity of NH₃-N loss varied from 19 to 50% of the applied NH₄⁺-N at 33 to 550 kg NH₄⁺-N/ha, respectively. The increasing temperature increased losses of NH₃-N from NH₄NO₃ which does not form precipitates with CaCO₃ or appreciable (NH₄)₂CO₃. In 100 hours, NH₄NO₃ lost 14, 18, and 26% of the applied NH₄⁺-N at 12, 22, and 32C, respectively. Both the total 100-hour NH₃-N losses and rates of NH₃-N loss were increased by increased temperatures; however, the percent of NH₃-N volatilized was unaffected by rates of NH₄⁺-N application. Ammonium sulfate losses from a noncalcareous Wilson clay loam buffered to the pH of the calcareous soil produced NH₃-N losses equivalent to NH₄NO₃ at 12C and lower than NH₄NO₃ at 32C. Ammonia nitrogen losses, both total NH₃-N and rates of NH₃-N loss, were similar to losses of NH₄NO₃ from the calcareous soils. Therefore in the calcareous Houston Black clay the NH₃-N loss caused by reaction of (NH₄)₂SO₄ with CaCO₃ ranged from 0 to 70 or 80%. Regression equations were developed that predict NH₃-N losses at certain temperatures, time, and rate of NH₄⁺-N application.