Influence of straw mulch and no-tillage on soil respiration, its components and economic benefit in a Chinese wheat–maize cropping system

Abstract

Optimizing economic benefit while reducing soil CO2 emissions in cropping systems has become the focus of agricultural study. We assessed the influence of short-term straw mulch and no-tillage on soil respiration (Rs), heterotrophic respiration (Rh), and autotrophic respiration (Ra), as well as economic benefit, in a traditional Chinese winterwheat and summermaize rotation system. Combinations of four treatments were tested: NS (no straw), SM (straw mulch), CT (conventional tillage) and NT (no-tillage). For wheat, SM significantly increased Rs in 2019 but significantly decreased Rs in 2020 relative to NS. NT significantly decreased Rs by 5.8% compared to CT from 2019 to 2020. For maize, during all three annual cycles, SM increased Rs relative to NS. NT increased Rs in 2018 with respect to CT but decreased it in 2019 and 2020. From the perspective of annual Rs both wheat and maize, SM increased Rs by 34.8%, 19.8%, and 18.8% in 2018, 2019, and 2020, respectively. NT increased Rs by 4.9%, −1.6%, and −0.7% in 2018, 2019, and 2020, respectively. The lowest annual Rs occurred for SM+NT in 2020. Relative to NS and CT, SM and NT promoted Rh but inhibited Ra for wheat during 2019 and 2020. For maize, SM increased Rh and suppressed Ra while NT had no significant effect on Rh and suppressed Ra. Therefore, SM increased Rs by promoting Rh, while NT decreased Rs by inhibiting Ra. In all treatments, Rh averaged 1.82–3.36 times higher than Ra. Soil temperature had a greater influence on temporal variations in soil respiration than soil moisture. Averaged from 2018 to 2020, the annual economic benefit was increased by 11.7% and 15.3% in SM and NT than NS and CT, respectively. Our results suggest that straw mulch and no-tillage should be promoted as an environment-friendly agroecosystem management practice for wheat and maize, as these practices can achieve a balance between improving economic benefit and reducing soil CO2 emissions, contributing to the mitigation of climate change and the early achievement of carbon neutrality goals.