Sustainable use of Water for Some Selected Hybrid and Inbred Rice Cultivation in the Floodplain Areas (AEZ 26 and AEZ 28) of Bangladesh

Abstract

The water crisis is threatening the sustainability of the irrigated rice system and food security in Asia. Our challenge is to promote novel technology and production systems that allow rice cultivation to be maintained in the declining water availability. This paper introduces principles for sustainable water use and water saving technology for reducing water inputs and increasing water productivity, and assesses the opportunities of such technologies and systems at spatial scale levels from plant to field, to irrigation system, and to agro-ecological zones. The rapid growth of world population has resulted in significantly increased global water demand. According to a recent repo1t on limited water supply, conservation techniques and water use policies are needed to preserve water resources. Worldwide agriculture is the largest consumer of water, particularly for growing rice. Water use for rice production was chosen because rice will continue to be a staple crop for the majority of the world's population and because of its pervasive use of water. Traditional lowland rice production in Asia requires much water: it consumes more than 50% of all irrigation water used in Asia. Water resources are, however, increasingly getting scarce and expensive. The supply of water for irrigation is endangered by declining water quality, declining resource availability, increased competition from other users, and increasing costs. During the past decades, rice production in Bangladesh experienced an impressive intensification. The change to dry season rice, constituting about 60% of national rice production, was largely due to groundwater irrigation by shallow tube wells (STW) and deep tube wells (DTW). This practice led to the massive extraction of groundwater, an overexploitation of groundwater, locally manifested by declining groundwater tables in Rajshahi. Co1Tespondingly to the expansion of i1Tigation, demand for energy increased, as electricity or fuel are needed to lift groundwater to the surface. This also touches on the chronically deficient energy situation of Bangladesh. To address problems of water scarcity, researchers have studied and developed a number of water-saving i1Tigation technologies such as saturated soil culture and alternate wetting and drying (A WD) that can drastically diminish these losses. Under these technologies, yields may decline, but they have demonstrated that they save water and increase water productivity. Hence, this thesis was designed to investigate water conservation possibilities for rice production in two water management regimes: alternate wetting and drying and continuous standing (the latter is the traditional water management technique in iITigated rice culture). The study revealed that the alternate wetting and drying treatment reduced water use and increased rice grain yield than continuous standing water. Among the results of the study, it was found that BRRJ hybrid2 gave better performance than other inbred varieties. Logistic regression model used to estimate the contribution of key variables of adoption of A WD. Boro rice, it was suggested that farm size, education of household head, and contact with extension agents, water scarcity and dissemination through demonstration were the variables that had significant impact on the adoption of A WD. It was also evident that water conservation benefits can potentially be realized if local government agencies (e.g., Phil- Rice and NIA), as well as international agencies ( e.g., IRRI), continue to provide education and training about the latest research on A WD and other water-conserving technologies to local extension personnel, field technicians, and as well as farmers. With calls for re-orientation of sustainable water use, the implications of the findings of this research suggest that alternate wetting and drying water saving technology is making a positive contribution towards sustainability. It should be a valuable approach that should not be trivialized, stigmatized or ignored because of its potential to bring long-lasting impacts.