Crop straw retention influenced crop yield and greenhouse gas emissions under various external conditions

Crop straw retention is a strongly recommended practice for sustainable agricultural production in China. However, a comprehensive analysis of straw retention effects on crop yield, N₂O and CH₄ emissions, net greenhouse gas (NGHG), and net greenhouse gas intensity (NGHGI) and their response to various external influence factors, including location/climatic conditions, soil properties, and field management practices, in a national scale were easily ignored. Based on the collected published literatures, we found that straw retention improved crop yield and N₂O and CH₄ emissions by 4.7% (-4.6 to 25.8%), 18.3% (-26.6 to 57.6%), and 21.0% (-49.0 to 214.5%) in contrast with no-straw retention. For different external conditions, crop yield was increased by 15.9% in temperate zone and 10.7% in upland soils with straw retention. N₂O emissions which correspond to the above conditions were enhanced by 42.2% and 18.8%, while CH₄ emissions were restrained by 49.0% in temperate zone. Negligible changes in crop yield and N₂O emissions were observed for subtropical zone or paddy soils, but with increase in CH₄ emissions. Additionally, straw retention enhanced NGHG and NGHGI by 20.7% and 15.4% on average regardless of various external conditions, respectively. However, NGHG was reduced under conditions of straw retention in temperature or mulching to field. Straw retention under appropriate site-specially conditions simultaneously safeguard food security and slightly increase environmental effects.