New ridge–furrow irrigation system reduces methane emissions and partial global warming potential in rice cultivation

Abstract Flood irrigated rice, in addition to using large volumes of water, is one of the main causes (~30%) of methane (CH4) emissions from agriculture. New cultivation technologies in lowlands, such as ridge-furrow, enable the use of a smaller volume of water in rice cultivation compared to traditional flood irrigation and higher soil oxidation, which can impact the emission of CH4 and nitrous oxide (N2O). The expansion of the use of the ridge-furrow system in southern Brazil occurs because it has been one of the systems responsible for the expansion of alternative crops, such as soybean and corn in rotation with rice. The ridge-furrow promotes adequate drainage of the soil surface and irrigation of crops, minimizing damage from excess and deficit water in lowlands. Thus, the objective of the work was to evaluate the emission of CH4, N2O, partial global warming potential (pGWP) and rice grain yield in a ridge-furrow system in rotation with soybean. The trial was carried under field conditions at the Ricetec Experimental Station, in the 2020/21 and 2021/22 crop seasons in Capão do Leão, Southern Brazil, taking advantage of the infrastructure of ridge-furrow established for soybean in rotation in the previous season. Was used an XP117 RiceTec rice hybrid with a 130-day cycle. The treatments consisted of different portions of the furrow: upper (wet soil); intermediate (saturated soil) and bottom portion (flooded soil). Rice cultivation in the ridge-furrow system reduced CH4 emissions by 34% and partial global warming potential by 30%. Rice grain yield levels remained high in the ridge-furrow system. Thus, the ridge-furrow irrigation contributes to increasing the sustainability of rice production as it enables a significant reduction in CH4 emissions and a more efficient in the use of water.