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Title: AMMONIA VOLATILIZATION FROM DIFFERENT FERTILIZER SOURCES AND EFFECTS OF TEMPERATURE AND SOIL PH.

Author
item HE, Z - UNIV OF FLA
item Alva, Ashok
item CALVERT, D - UNIV OF FLA
item BANKS, D - UNIV OF FLA

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/1999
Publication Date: N/A
Citation: HE, Z.L., ALVA, A.K., CALVERT, D.V., BANKS, D.J. AMMONIA VOLATILIZATION FROM DIFFERENT FERTILIZER SOURCES AND EFFECTS OF TEMPERATURE AND SOIL PH. SOIL SCIENCE, 164:750-758. 1999.

Interpretive Summary: Gaseous loss of ammonia from ammonium form of N fertilizer applied to soil is termed as volatilization. This process is dependent on various soil properties and represents a net loss of N from soil-plant system. In a Riviera fine sand (an Alfisol) with pH 7.9, the volatilization loss of ammonia was 23.2% for ammonium bicarbonate, 21.7% for ammonium nitrate. The volatilization increased with an increase in soil pH, and soil temperature. The transformation of ammonium to nitrate form is termed as nitrification. This process decreases at high temperature, thus, results in increased amount of N present as the ammonium form, which contributes to increased volatilization losses.

Technical Abstract: Improved understanding of nitrogen sources, environmental factors, and nitrification effects on NH3 volatilization is needed for optimal management of nitrogen in crop production systems. In the laboratory, a sponge-trapping and KCl-extraction method was modified for measuring NH3 volatilization from different N sources as affected by temperature and soil lpH. The kinetics of NH3 volatilization from four N sources, surface applied to an Alfisol (a Riviera fine sand, pH 7.9) followed an initial rapid reaction, and then a slow reaction, which was adequately described by a Langmuir kinetic model. The potential maximum NH3 volatilization (qm) under the experimental conditions, as predicted by the Langmuir equation, decreased in the order: NH4HCO3 (23.2% of applied NH4-N) > (NH4)2SO4 (21.7% > CO(NH2)2 (21.4%) > NH4NO3 (17.6%). With an increase in NH4-N application rate, NH3 volatilization increased significantly for (NH4)2SO4, CO(NH2)2, a aNH4HCO3 but decreased for NH4NO3. Ammonia volatilization was minimal at the initial soil pH of 3.5 and increased rapidly with increasing pH up to 8.5. The potential maximum NH3 volatilization increased by 2- and 3- fold, respectively, with an increase in the incubation temperature from 5 to 25oC, and from 25 to 45oC, respectively. The greatly enhanced NH3, volatilization at 45oC, compared with that at 25oC, was related to the inhibition of nitrification at the high temperature, which increased the availability of NH4 for NH3 volatilization over a prolonged period of time.