Ammonia Volatilization from Surface Applications of Ammonium Compounds on Calcareous Soils: I. General Theory

作者：L. B. Fenn, D. E. Kissel · 发表于：Soil Science Society of America Journal · 年份：1973 · DOI：10.2136/sssaj1973.03615995003700060020x · 被引用次数：151 · 研究领域：Clay minerals and soil interactions、Soil and Unsaturated Flow、Soil Carbon and Nitrogen Dynamics

Abstract Volatilization of NH 3 from NH 4 ‐ ‐N salts applied to the surface of a calcareous soil was investigated. Ammonia losses from surface applied NH 4 F, (NH 4 ) 2 SO 4 , and (NH 4 ) 2 HPO 4 were 68, 54, and 51%, respectively, of the added NH 4 ‐ ‐N in 100 hours. Ammonium nitrate, NH 4 Cl, and NH 4 I lost 18, 18, and 16%, respectively, of the added NH 4 ‐N in 100 hours. An increase in pH at the soil surface resulted in higher loss of NH 3 . Applications of 550 kg N/ha as NH 4 F and (NH 4 ) 2 SO 4 increased the pH from 7.6 to 8.9 and 8.1, although pH decreased rapidly with time. Soil pH decreased to 6.8 by the addition of 550 kg NH 4 ‐N/ha as NH 4 NO 3 and changed very little in 50 hours. Ammonium sulfate applied to soils saturated with Mg 2+ and Ba 2+ gave similar results. Solubility of the apparent reaction product was the major factor regulating NH 3 volatilization. Formation of a Ca 2+ reaction product, such as CaSO 4 , tends to drive the reaction to the right and favors formation of (NH 4 ) 2 CO 3 . A proposed mechanism of the observed loss of NH 3 is as follows: when an ammonium salt dissolves in a calcareous soil, (NH 4 ) 2 CO 3 and a Ca 2+ salt of varying solubility forms. Ammonium carbonate subsequently decomposes, losing CO 2 at a faster rate than NH 3 . This causes formation of NH 4 OH and an increase in pH and greater NH 3 losses.