Effects of Irrigation Regimes and Rice Varieties on Methane Emissions and Yield of Dry Season Rice in Bangladesh

Abstract

Adoption of the right rice variety and water-saving irrigation method could reduce greenhouse gas (GHG) emissions in lowland rice cultivation. A study was conducted at the research farm of Bangladesh Agricultural University, Mymensingh, Bangladesh, in 2019 during the Boro (dry) season to determine the impacts of different rice varieties (BRRI dhan29, BRRI dhan47, BRRI dhan69, Binadhan-8, Binadhan-10, and Binadhan-17) on methane (CH4) emissions under two irrigation methods, i.e., alternate wetting and drying (AWD) and continuous flooding (CF). The treatments were laid out in a split-plot design, considering water regime as the main plots and rice variety as the sub-plots. The emission rates of CH4 were determined by collecting air samples using the closed chamber technique and measuring the concentrations using a gas chromatograph. CH4 emission rates varied with the growth and development of the rice varieties. The lowest cumulative CH4 emission rate was observed in Binadhan-17, particularly under AWD irrigation. Across the rice varieties, AWD irrigation significantly reduced the cumulative CH4 emissions by about 35% compared with CF. No significant variation in rice yield was observed between AWD (5.38 t ha−1) and CF (5.16 t ha−1). This study suggests that the cultivation of Binadhan-17 under AWD irrigation could be effective at reducing the carbon footprint of lowland rice fields.

Effect of Alternate Wetting and Drying on the Emission of Greenhouse Gases from Rice Fields on the Northern Coast of Peru

“…In Figure 7, it can be observed that the highest emission rates were under the CF regimen. Although these emission rates are comparable to those recorded in other locations (Table 5) [3,5,14,16], there are studies reporting higher [2,12,19] or lower values [6,10].…”

“…According to the crop phenology, CH 4 emissions increase as the plants grow until reaching the flowering stage. This increase is due to the optimal development of aerenchyma tissue, especially in the early stages of plant development, leading to increased exudate release and fermentation of easily degradable soil organic matter [10]. Thus, peak emission levels were recorded during the vegetative stage (17.924 mg m −2 h −1 in CF and 2.778 mg m −2 h −1 in AWD) and the reproductive stage (8.214 mg m −2 h −1 in CF and 1.353 mg m −2 h −1 in AWD).…”

“…In recent years, non-continuous flooding irrigation methods have been developed as a solution, reducing water use by up to 38% without affecting yield [10]. The Alternate Wetting and Drying (AWD) irrigation regimen stands out as one of the most studied and globally employed methods [5].…”

“…It involves cycles of wetting and drying the soil, leading to changes in soil moisture and redox conditions [5,6,11]. It has been proven that this irrigation regimen can reduce GHG emissions by up to 40%, as it decreases CH 4 emissions by enhancing aerobic processes in the soil during the drying period [10,11].…”

“…Therefore, this study focused on investigating CH 4 and N 2 O emissions at three different AWD irrigation levels (5,10, and greater than 20 cm depth) and their influence on grain yield compared to the conventional CF regimen. The specific objectives of the study were to (i) quantify CH 4 and N 2 O emission flows, (ii) calculate the Global Warming Potential (GWP) and its relationship with the crop yield (YGWP), and (iii) determine the emission factors (EF) for CH 4 and N 2 O.…”