Effect of straw incorporation on methane emission in rice paddy: conversion factor and smart straw management

Abstract

Straw incorporation is strongly recommended in rice paddy to improve soil quality and mitigate atmospheric carbon dioxide (CO 2), via increasing soil organic carbon (SOC) stock. However, straw application significantly increased methane (CH 4) emission during rice cultivation, and then its incorporation area was not expanded effectively. To find the reasonable straw management practice which can reduce CH 4 emission without productivity damage, the effect of straw incorporation season and method on CH 4 emission was investigated at six different textured paddy fields in South Korea for 2 years. A straw was applied right after rice harvesting in autumn, and the other right before rice transplanting in spring. In the autumn application, straw was applied with two different methods: spreading over soil surface or mixing with soil. Straw application significantly increased seasonal CH 4 flux by average 28-122% over 197-590 kg CH 4 ha −1 of the no-straw, but its flux showed big difference among straw applications. Fresh straw application before transplanting increased seasonal CH 4 flux by approximately 120% over the no-straw, but the autumn application reduced its CH 4 flux by 24-43% over 509-1407 kg CH 4 ha −1 of the spring application. In particular, the seasonal CH 4 flux was approximately 24% lower in straw mixing with soil after autumn harvesting than 423-855 kg CH 4 ha −1 in straw spreading over surface. However, CH 4 fluxes were not significantly discriminated by soil and meteorological properties in the selected condition. Straw application slightly increased rice grain yield by approximately 4% over the no-straw, but rice productivity was not statistically different among straw applications. Spring straw application increased CH 4 intensity which means seasonal CH 4 flux per grain yield by the maximum 220% over the no-straw. Autumn straw application significantly decreased CH 4 intensity by average 24-65% over the spring straw application. In particular, CH 4 intensity in straw mixing with soil treatment was not statistically different with the no-straw. Therefore, autumn straw application with mixing inner soil could be a reasonable straw management practice to decrease CH 4 emission impact with improving soil productivity.

In-situ Rice Residue Management Practices and Its Impact on Climate, Soil Fertility and Crop Productivity: A Review

“…derived from anaerobic oxidation [32]. Yet, using straw considerably boosted methane (CH4) emission from anaerobic degradation during rice cultivation [33].…”

Comprehensive Impacts of Climate Change on Rice Production and Adaptive Strategies in China

“…According to the actual circumstances of the rice planting areas, to carry out appropriate supporting cultivation measures, such as green manure cropping winter cover and protective lime amendment measures can be implemented. Additionally, measures such as the promotion of returned straw and intermittent irrigation, and the promotion of soil testing formulas and precise fertilization and the development of carbon reduction emissions of rice planting patterns can be expanded ( Jiang R. et al, 2017 ; Jiang et al, 2018 , 2019 ; Song et al, 2019 ; Qian et al, 2022 ). The author thinks intelligent rice technology should include three modules, namely, the rice productivity technology (adaptive cultivation technology), soil organic carbon sequestration technology and paddy GHG emissions reduction technology.…”

Agricultural practices to improve soil carbon sequestration in rice paddy soils

“…2). At the early rice growth stage, CH 4 is emitted at a lower rate, but its flux steadily increases with plant growth and development of anaerobic soil conditions (Ali et al, 2009a;Kim et al, 2015;Haque et al, 2016;Jeong et al, 2018;Song et al, 2019;Lee et al, 2020a,b;Song et al, 2021).…”