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.

Novel Technological and Management Options for Accelerating Transformational Changes in Rice and Livestock Systems

“…While there were significant differences in the N 2 O emissions observed in 2015 compared to those observed in 2016, the soil N 2 O emissions observed during the drier year (2015) were higher in the AWD (1.53 kg N 2 O ha −1 ) than in the continuously flooded (0.56 kg N 2 O ha −1 ) plots, but in both years the treatment differences were not significant at a 5% level of significance. This finding corroborates those of Linquist et al [29], who also report no significant difference in N2O emissions between CF and AWD for rice-rice rotation systems. The CH 4 emissions in the continuous flooded plots were generally significantly lower than those estimated using the global average estimated through a meta-analysis (134 kg CH 4 ha −1 season −1 ) conducted by Linquist et al [30].…”

Alternate wetting and drying reduces methane emission from a rice paddy in Central Java, Indonesia without yield loss

“…It is known that every kg of rice has traditionally need 1900-5000 L of water (Bouman et al 2007); therefore, instead of continuous flooding, a technique to save/conserve water in rice field, alternate wetting and drying (AWD), have been developed by the International Rice Research Institute (IRRI) (Price et al 2013). Comparing to continuous flooding, AWD reduced the global warming potential (GWP) of CH 4 and N 2 O emissions by 45-90% (Linquist et al 2014), reduced irrigation water by 15-35% without significant yield loss (Siopongco et al 2013), and can increase food security (Bouman et al 2007). The other benefit of AWD was the reduction of arsenic accumulation in the grain by 64% (Linquist et al 2014).…”

“…Comparing to continuous flooding, AWD reduced the global warming potential (GWP) of CH 4 and N 2 O emissions by 45-90% (Linquist et al 2014), reduced irrigation water by 15-35% without significant yield loss (Siopongco et al 2013), and can increase food security (Bouman et al 2007). The other benefit of AWD was the reduction of arsenic accumulation in the grain by 64% (Linquist et al 2014).…”

Managing Water and Soils to Achieve Adaptation and Reduce Methane Emissions and Arsenic Contamination in Asian Rice Production

“…Linquist et al [296] compared arsenic uptake on experimental plots in the southern United States, in a two-year study involving rice-rice (RR) and rice-soybean (RS) rotations. The irrigation treatments included continuous flooding (flooded control) and three versions of alternative wetting and drying: AWD/40F, AWD/60, and AWD/40.…”

“…In the AWD/40F treatment, the fields were managed in the same manner as the AWD/40 treatment, until the plants reached the reproductive stage. From that time forward, flooding was maintained until the field was drained for harvest [296].…”