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Title: TEMPERATURE QUOTIENTS OF AMMONIA EMISSION OF DIFFERENT NITROGEN SOURCES APPLIED TO FOUR AGRICULTURAL SOILS

Author
item LIU, G - UNIV OF FLORIDA
item LI, Y - UNIV OF FLORIDA
item Alva, Ashok

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2006
Publication Date: 2/1/2007
Citation: Liu, G., Y Li, and A.K. Alva. 2007. Temperature quotients of ammonia emission of different nitrogen sources applied to four agricultural soils. Soil Science Society of America Journal. 71:1482-1489.

Interpretive Summary: Nitrogen (N) fertilizer containing ammonium (NH4) and/or source which produce ammonium as intermediate product are subject to gaseous loss of ammonia (NH3). This process is termed as volatilization loss of NH3. Temperature plays a major role in determining volatilization loss. Effects of temperature on volatilization loss were investigated in two soils from Florida (Biscayne Marl soil and Krome gravelly loam soil) and two from Washington (Quincy fine sand and Warden Silt loam.) Nitrogen sources either as potassium nitrate, ammonium nitrate, ammonium sulfate or urea were examined in this study at either 11, 20, or 29 degrees C and either 20 or 80% field capacity soil water regimes. Temperature quotient (Q9) was defined as the change in rate of NH3 emission corresponding to a 9 degree C change in temperature. Temperature quotient of ammonia emission from either ammonium nitrate or ammonium sulfate was 10-fold greater for the Warden Silt loam soil as compared to that for the other three soils. This study demonstrated that temperature dependency of ammonia emission was greater for Warden Silt loam soil as compared to that for the other three soils being investigated. However, further study is needed to understand the specific properties of the soil which contribute to greater temperature dependency of ammonia emission in a given soil.

Technical Abstract: Emitted ammonia (NH3) is the primary gaseous form of nitrogen (N) loss from N sources applied to soils, which contain instant or transformable ammonium (NH4+). However, our knowledge of NH3 volatilization in relation to temperature is incomplete. This research was conducted using Biscayne Marl Soil (BMS), and Krome Gravelly Loam (KGL) from Florida, and Quincy Fine Sand (QFS), and Warden Silt Loam (WSL) soils from Washington. Each soil was amended with either potassium nitrate, ammonium nitrate (AN), ammonium sulfate (AS) or urea, and incubated at 11, 20 or 29 oC under 20% and 80% field water capacity (FC). A change in the rate of NH3 emission corresponding to a 9 oC change in temperature is expressed as the temperature quotient (Q9), which directly describes the effect of temperature on the rates of NH3 volatilization. At 20 oC, the cumulative ammonia emission at 20% FC was up to 8.1-fold greater than at 80% FC. The Q9 values of NH3 emission from the WSL soil were up to 10-fold greater than those from the other three soils amended with AS and AN. Based on Q9 and the Arrhenius Equation, the Arrhenius Activation Energy (Ea) was calculated. Ea was about 45 cal/mol for the WSL soil but either equal to or less than 10 cal/mol for the other soils. NH3 volatilization from the WSL soil was highly dependent on temperature. These results indicate that Q9 and Ea could provide new technical support for fertilization strategies in crop production.