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United States Department of Agriculture

Agricultural Research Service

Research Project: Developing Sustainable Cropping Systems to Improve Water Productivity and Protect Water and Soil Quality in Irrigated Agriculture

Location: Water Management Research

Title: Effect of urea application rate and water content on nitrous oxide emission from a sandy loam soil - a laboratory study

Authors
item Cai, Zejiang -
item Gao, Suduan
item Hendratna, Aileen
item Duan, Yinghua -
item Hanson, Brad -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2014
Publication Date: February 4, 2014
Citation: Cai, Z., Gao, S., Hendratna, A., Duan, Y., Hanson, B. 2014. Effect of urea application rate and water content on nitrous oxide emission from a sandy loam soil - a laboratory study. California Plant and Soil Conference Proceedings. p.131.

Technical Abstract: Agriculture is a major contributor to global anthropogenic nitrous oxide (N2O, a potent greenhouse gas) emission. Data from a pomegranate orchard indicate that N2O emission is highly variable with nitrogen application rates and irrigation methods. The aim of this study was to investigate the effect of urea application and soil water content on N2O emission and associated N transformation in a laboratory incubation experiment. Surface soil (Hanford fine sandy loam) was sampled from a pomegranate orchard near Parlier, California. Dynamics of soil ammonium (NH4+), nitrite + nitrate (NO2-+NO3-) and emission of N2O were monitored from urea application at 0, 50, 100, 150 mg N kg-1 with 10% water content (w/w) and 100 mg N kg-1 with 5%, 10%, 20% (above field capacity), 30% (flooded) soil water contents. Soil was incubated in a constant temperature (25 degrees) for 35 days. The average fluxes of N2O emission (ranged from 0.73 to 14.03 µg N2O-N kg-1 h-1) rose significantly with increasing N rates at 10% soil water content. At 20% and 30% water content the fluxes of N2O emission increased abruptly to 124 and 140 µg N2O-N kg-1 h-1 from 3.43 and 4.94 µg N2O-N kg-1 h-1 for 5% and 10% water content, respectively at 100 mg N kg-1 treatment. The results indicated that N2O emission increased significantly with higher urea application rates and soil water content. The data partially explains why surface drip irrigation (higher water content in surface soil) resulted in much higher N2O emissions than subsurface drip (dry surface soil) that was observed in the field. This research continues to examine other factors (e.g., temperature, soil organic matter) on N2O emissions.

Last Modified: 8/29/2014
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