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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #320600
Title: Alternate wetting and drying in high yielding direct-seeded rice systems accomplishes multiple environmental and agronomic objectives

Author
item LAHUE, GABRIEL - University Of California
item Chaney, Rufus
item ADVIENTO-BORBE, MARIA - University Of California
item LINQUIST, BRUCE - University Of California

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2016
Publication Date: 6/1/2016
Citation: Lahue, G.T., Chaney, R.L., Adviento-Borbe, M.A., Linquist, B.A. 2016. Alternate wetting and drying in high yielding direct-seeded rice systems accomplishes multiple environmental and agronomic objectives. Agriculture, Ecosystems and Environment. 229:30-39.

Interpretive Summary: Rice production is a source of greenhouse gas emissions, and water limitations threaten rice production economics. Traditional flood irrigation has been found to produce maximal gasses and use maximal water, and Alternative Wetting and Drying (AWD) irrigation practices have been developed as an alternative which reduces greenhouse gas emissions, increases water use efficiency, and reduces arsenic in rice grain. But some AWD practices have caused significant yield reduction. Thus a two year experiment was undertaken to evaluate less severe AWD irrigation effects on greenhouse gas release, water use efficiency, and grain arsenic concentrations. The key change was the point of soil water content at which irrigation was practiced, based on volumetric water content average of the replications based on the physics of water in the test soil. Yield was high (over 10,000 kg/ha) while annual global warming potential by 57-74% compared to the flood culture standard method. Partly because of soil properties and irrigation practices, arsenic in brown and milled rice were well below the CODEX As limit, and AWD significantly reduced brown rice grain total As from 0.142 mg/kg to 0.52 mg/kg in water seeded AWD and 0.62 mg/kg in the drill-seeded AWD. Total As in milled rice was 1.14 mg/kg in flood irrigated rice, but only 0.039 mg/kg in water seeded AWD and 0.046 mg/kg in drill seeded AWD. The AWD method tested maintained grain yield, reduced greenhouse gas emissions and global warming potential, improved water use efficiency, and reduced grain As significantly. This method of managing AWD offers more favorable outcomes than earlier AWD management methods studied previously.

Technical Abstract: Rice cultivation is critically important for global food security, yet it also represents a significant fraction of agricultural greenhouse gas (GHG) emissions and water resource use. Alternate wetting and drying (AWD) of rice fields has been shown to reduce both methane (CH4) emissions and water use, but its effect on grain yield is variable. In this two-year study we measured CH4 and nitrous oxide (N2O) emissions, rice grain total arsenic (As) concentrations, nitrogen use efficiency (NUE), and rice grain yield from two AWD treatments (drill-seeded and water-seeded) and a conventionally managed water-seeded treatment (control). Grain yields (average = 10,188 kg ha-1) were similar or higher in the AWD treatments compared to the control and required similar or lower N rates to achieve these yields. Furthermore, AWD reduced growing season CH4 emissions by 60 – 87% while maintaining low annual N2O emissions (average = 0.38 kg N2O-N ha-1); N2O emissions accounted for < 15% of the annual global warming potential (GWP) in all treatments. As a result, the AWD treatments reduced annual GWP by 57 – 74% and yield-scaled GWP by 59 – 88%. Fallow season emissions accounted for 22 – 53% of annual CH4 emissions and approximately one third of annual GWP on average. Milled grain total As, which averaged 0.114 mg kg-1 in the control, was reduced by 59 – 65% in the AWD treatments. These results show that AWD has the potential to mitigate GHG emissions associated with rice cultivation and reduce rice grain As concentrations without sacrificing grain yield or requiring higher N inputs; however future research needs to focus on adapting AWD to field scales if adoption of this technology is to be realized.