title: Reducing greenhouse gas emissions, water use, and grain arsenic levels in rice systems.
abstract: Agriculture is faced with the challenge of providing healthy food for a growing population at minimal environmental cost. Rice (Oryza sativa), the staple crop for the largest number of people on earth, is grown under flooded soil conditions and uses more water and has higher greenhouse gas (GHG) emissions than most crops. The objective of this study was to test the hypothesis that alternate wetting and drying (AWD--flooding the soil and then allowing to dry down before being reflooded) water management practices will maintain grain yields and concurrently reduce water use, greenhouse gas emissions and arsenic (As) levels in rice. Various treatments ranging in frequency and duration of AWD practices were evaluated at three locations over 2 years. Relative to the flooded control treatment and depending on the AWD treatment, yields were reduced by <1-13%; water-use efficiency was improved by 18-63%, global warming potential (GWP of CH4 and N2 O emissions) reduced by 45-90%, and grain As concentrations reduced by up to 64%. In general, as the severity of AWD increased by allowing the soil to dry out more between flood events, yields declined while the other benefits increased. The reduction in GWP was mostly attributed to a reduction in CH4 emissions as changes in N2 O emissions were minimal among treatments. When AWD was practiced early in the growing season followed by flooding for remainder of season, similar yields as the flooded control were obtained but reduced water use (18%), GWP (45%) and yield-scaled GWP (45%); although grain As concentrations were similar or higher. This highlights that multiple environmental benefits can be realized without sacrificing yield but there may be trade-offs to consider. Importantly, adoption of these practices will require that they are economically attractive and can be adapted to field scales.
authors.affiliation: Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Linquist
authors.forename: Merle M
authors.initials: MM
authors.lastname: Anders
authors.forename: Maria Arlene A
authors.initials: MA
authors.lastname: Adviento-Borbe
authors.forename: Rufus L
authors.initials: RL
authors.lastname: Chaney
authors.forename: L Lanier
authors.initials: LL
authors.lastname: Nalley
authors.forename: Eliete F F
authors.initials: EF
authors.lastname: da Rosa
authors.forename: Chris
authors.initials: C
authors.lastname: van Kessel
mesh_terms: D057914:Agricultural Irrigation / Q000379:methods* / Q000706:statistics & numerical data; D000383:Agriculture / Q000379:methods* / Q000706:statistics & numerical data; D001131:Arkansas; D001151:Arsenic / Q000032:analysis*; D002245:Carbon Dioxide / Q000378:metabolism; D017752:Greenhouse Effect / Q000517:prevention & control*; D015233:Models, Statistical; D012275:Oryza / Q000737:chemistry* / Q000254:growth & development*; D012639:Seeds / Q000737:chemistry
chemical_list: D002245:Carbon Dioxide; D001151:Arsenic
keywords: Oryza sativa; alternate wetting and drying; arsenic; greenhouse gas emissions; irrigation management; sustainable intensification; water-use efficiency