Ammonia Volatilization from Soils
1974
Mills, Harry A. | Barker, Allen V. | Maynard, Donald N.
If NH₄⁺-N fertilizers are used, most agronomic crops grow best if the soil reaction is near neutrality. Previous studies have shown that if the soil pH becomes alkaline, NH₃ volatilization losses of N occurs. The objective of this study was to determine whether or not a rapidly growing crop could reduce the volatilization losses of N, especially from soils above pH 7 to which large applications of NH₄⁺-N fertilizers were made. This study was conducted in a greenhouse using a closed system in which all NH₃ evolved from the soil was swept away by a stream of air and collected. The amount of NH₃-N evolved from the soils was measured as a function of time, soil pH, amount of N application, and presence or absence of corn (Zea mays indentata Bailey) seedlings. Ammonia losses with or without plants in the system increased as the soil reaction and amount of NH₄⁺-N application increased. A sharp upward inflection in NH₃-N loss occurred at pH 7.2. Plants reduced NH₃-N losses by atleast 60% in the alkaline soils and by lesser amounts in the acidic and neutral soils. Rapid absorption of NH₄⁺-N by plant roots appeared to account for the conservation of N.
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