Abstract
Irrigation water supply is one of the vital components for sustainable rice farming, which is becoming a limiting resource in the changing climatic condition. An experiment was conducted at the research field of Bangladesh Agricultural University, Mymensingh during dry season from January-June of 2017 to investigate the suitability of Alternate Wet and Dry Irrigation (AWDI) for sustainable rice production and reducing methane emission. The modern rice variety BINA Dhan 10 was used as test crop. There were five irrigation treatments viz. T1 (saturated condition), T2 (continuous flooded, 5 cm standing water), T3 (AWDI-10 cm; irrigated when water level fell 10 cm from surface), T4 (AWDI-15 cm; irrigated when water level fell 15 cm from surface) and T5 (AWDI-20 cm; irrigated when water level fell 20 cm from surface). Results of the field trial showed satisfactory grain yield and low seasonal methane emission along with significantly high irrigation water savings (%) in AWDI treated field plots. Among the treatments, T3 (AWDI-10 cm) and T4 (AWDI-15 cm) showed higher yield performance (6250kg.ha-1 and 5810 kg.ha-1, respectively) with lower CH4 emission (reduced up to 36% and 40%, respectively) compared to continuous flooded treatment (T2, CF 5 cm water). In AWDI field plots less irrigation frequency (6 - 9) was required which significantly saved the amount of irrigation water (12% - 24%). Although T5 (AWDI-20 cm) showed the highest water savings (24%) and lowest CH4 emission (reduced up to 50%); however the lowest grain yield (4283 kg.ha-1) was found under this treatment. On the other hand, continuously irrigated (T2, 5 cm standing water) field plot showed lower yield (4783 kg.ha-1) but significantly higher methane emissions compared to other treatments during rice cultivation. Water productivity index was also found higher in AWDI treated field plots compared to continuously irrigated field plot. At the reproductive stage of rice plant well-developed aerenchyma tissue was observed in root cortex under the continuous irrigated field plot, which indicates higher diffusion pathway of methane gas from root rhizosphere to the atmosphere compared to other treatments. Therefore, alternate wet and dry irrigation water management practice may be recommended at farmers’ level for sustainable rice production and reducing methane emission during dry winter Boro season which will reduce the cost of production by water saving as well as energy saving.
Highlights
Global agriculture in 21st century faces the tremendous challenge of providing sufficient and healthy food for growing population under increasing water scarcity, while minimizing environmental consequences
T3 (AWDI-10 cm) and T4 (AWDI-15 cm) showed higher yield performance (6250 kg∙ha−1 and 5810 kg∙ha−1, respectively) with lower CH4 emission compared to continuous flooded treatment (T2, CF 5 cm water)
Flooded rice cultivation is a major anthropogenic source of methane (CH4) which is one of the important greenhouse gases having 25 times more global warming potential than carbon dioxide (Nieder & Benbi, 2008). These flooded soils characterized by low oxygen and high organic substrates offering an ideal environment for methanogen bacteria generate anaerobic condition that favors CH4 production as an end product from organic matter degradation (Conrad, 2002)
Summary
Global agriculture in 21st century faces the tremendous challenge of providing sufficient and healthy food for growing population under increasing water scarcity, while minimizing environmental consequences. Rice cultivation especially in dry winter (Rabi) season requires huge amount of irrigation water, which is a great challenge due to energy crisis. Flooded rice cultivation is a major anthropogenic source of methane (CH4) which is one of the important greenhouse gases having 25 times more global warming potential than carbon dioxide (Nieder & Benbi, 2008). These flooded soils characterized by low oxygen and high organic substrates offering an ideal environment for methanogen bacteria generate anaerobic condition that favors CH4 production as an end product from organic matter degradation (Conrad, 2002). Methane from soil is derived from C mineralization, moisture, pH, soil Eh, etc. and emitted to the atmosphere by molecular diffusion, ebul-
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