A Nine-Year Study On The Effects Of Tillage On Net Annual Global Warming Potential In Double Rice-Cropping Systems In Southern China

It is important to look for management practices which can effectively reduce greenhouse gas emissions (GHGs) in agricultural systems. A field experiment was conducted during 2005-2014 to assess tillage impacts on net global warming potential (NGWP) including estimation of soil organic carbon (SOC) change and indirect emissions (IE) on a double rice system in Southern China. Three treatments used in this study were no tillage with residue retention (NT), rotary tillage with residue retention (RT), and plow tillage with residue incorporation (PT). In respect of SOC sequestration, annual mean rates (0-20 cm) were not significantly different between tillage treatments averaging 2.89 MgC ha(-1) yr(-1) during 2005-2014. Two-year (2013-2014) measurement of GHGs showed NT tended to significantly decrease annual CH4, but increase N2O emissions in the paddy soil. IE from farm inputs was found lowest in the NT treatment due to no additional tillage. NT and RT practices had better double rice yields by 0.8 % and 3.4 % relative to the PT without significant difference over the nine-year period. Lowest mean NGWP and NGHGI was found under the NT among all treatments in this study. The results suggested GHG mitigation and agricultural economic viability can be achieved by NT practice in double rice cropping systems. Meanwhile, the long-term effects of NT practice on rice yield and SOC storage should also be considered in future studies.