Optimal straw management co-benefits crop yield and soil carbon sequestration of intensive farming systems

Straw retention has been widely recommended to sequester more soil organic carbon (SOC) in agricultural soils, while carbon sequestration may not respond linearly to additional carbon input amount. The response of SOC, greenhouse gas (GHG) emissions and economic income to different straw management methods in intensive wheat-maize double cropping systems still need systematical study. An 8-year field experiment was conducted in the Huang-Huai-Hai Plain to investigate the impacts of optimal straw management (wheat straw was all crushed and spread on the soil surface, maize straw was all crushed and returned t into 0-15 cm soil layer) and optimal straw management (wheat straw was all crushed and spread on the soil surface, while maize straw was all harvested for feed) on SOC sequestrations, carbon economy and economic income. The results showed that only returning wheat straw into the field could maintain a similar crop yield (15.0 Mg ha(-1)) and SOC sequestration amount (9.06 Mg C ha(-1)) to the conventional straw management method. While this optimal straw management method kept a stable SOC sequestration rate of 1.24 Mg ha(-1) yr(-1) when the SOC sequestration rate decreased from 1.76 to 1.20 Mg ha(-1) yr(-1) in the conventional method. The optimal management method also further reduced GHG emissions by 85.4% and using maize straw as stock feed increased net income by 28.3%. Only returning wheat straw could realize economic and environmental benefits win-win in the wheat-maize double cropping systems, which provides important background knowledge about safe and sustainable agriculture.