Impact of alternate wetting and drying (AWD) on rice pest and the environment
2016
Bigornia, J.S.R. | Sparks, A.H. | Sander, B.O.
Alternate wetting and drying (AWD) is a technique known to reduce 15-30 water use over continuous flooding (CF). AWD also substantially reduce emissions of the greenhouse gas (GHG) methane by about 50%. The adoption of AWD by farmers depends on perceived benefits for example improved crop health which needs further scientific assessment. Experiments and surveys in farmers' fields were conducted to assess the effects of AWD on crop health under farmers' field conditions. Number of pesticide application was collected and Environmental Impact Quotient (EIQ) was used to compare environmental risk between AWD and CF fields. Weed coverage were significantly higher in AWD compared to CF. Insect damage and diseases such as bacterial leaf streak and leaf tungro were lower in AWD but an incidence of rice blast and brown spot was observed. No yield difference was observed between the systems. With the use of AWD, insecticide application was reduced to an average of 1.17, a reduction of more than 50% compared to CF (2.48). The number of herbicide application did not vary significantly between AWD and CF (1.23 and 1.30, respectively). Fungicide application slightly increased from 0.84 to 1 application because of the incidence of leaf blast and brown spot in AWD. Overall, field EIQ was 8.97 and 13.29 for AWD and CF respectively, a 33% decrease in environmental risk under AWD. AWD has been promoted in the past as a water-saving technology for rice production with modest rates of adoption. The results of this study show that the reduction of pest problems and no yield penalty in AWD are additional farmer benefits that may favor a wider uptake of AWD. The lower GHG coupled with the lower environmental risks make AWD a key option for climate change mitigation and adaptation and for sustainable rice production.
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