Environmental sustainability assessment of rice management practices using decision support tools

Rice has a large water demand and its cultivation is responsible for 8% of global anthropogenic methane (CH4) emissions. In this context, on-farm practices to increase water use efficiency and decrease greenhouse gas (GHG) emissions are increasingly being considered by rice producers. In this study, four water saving practices implemented in ten Arkansas rice farms during two consecutive years were evaluated: Multiple-Inlet Rice Irrigation (MIRI), zero grade (land leveling), Furrow-Irrigated Rice (FIR), and Alternate Wetting and Drying (AWD). The sustainability of these practices at the field level was evaluated with two decision support tools, Fieldprint Platform (FPP) and Cool Farm Tool (CFT). From a GHG perspective, both tools agreed that FIR and AWD were the best practices to decrease CH4 emissions. A sensitivity analysis with FPP was performed to detect which variables and management practices most affect metric scores. FIR was the best practice regarding GHG emissions due to the decrease in CH4 emissions; however, when considering energy use, FIR and zero grade increased energy use due to greater chemical applications. Initiatives such as AWD irrigation, burning the straw or other straw removal practices when practicing a rice-rice rotation, or making decisions about crop planting based on differences in soil type inside the farm should be encouraged to decrease CH4 emissions. The energy cost of agrochemical production had a large impact whereby even 10-20% reductions in application rates can significantly reduce the energy use. These decision support tools offer farmers an opportunity to evaluate their practices and increase farm sustainability; however, policy makers need to incentivize conservation practices and encourage creation of farmer networks to support adoption of sustainability practices.