CO2 fixation in above-ground biomass of summer maize under different tillage and straw management treatments

Abstract

This study was conducted to quantify the potential for CO₂ fixation in the above-ground biomass of summer maize (Zea mays L.) under different tillage and residue retention treatments. The treatments were paired and included conventional tillage with straw removed (CT₀), conventional tillage with straw retained (CT_S), no-till with straw removed (NT₀), no-till with straw retention (NT_S), subsoiling with straw removed (SS₀), and subsoiling with straw retained (SS_S). The results indicated that NT_S and SS_S can enhance translocation of photosynthates to grains during the post-anthesis stage. SS_S showed the highest total production (average of 7.8 Mg ha^-1), carbon absorption by crop (Cd) (average of 9.2 Mg C ha^-1), and total C absorption (Ct) (average of 40.4 Mg C ha^-1); and NT_S showed the highest contribution of post-anthesis dry matter translocation to grain yield (average of 74%). Higher CO₂ emission intensity and CO₂ fixation efficiency (CFE) were observed for straw retention treatments. In comparison with CT_S, the mean CFE (%) over four years increased by 26.3, 19.0, 16.5, and 9.4 for NT₀, SS₀, NT_S, and SS_S, respectively. Thus, SS_S and NT_S systems offer the best options for removing CO₂ from the atmosphere while enhancing crop productivity of summer maize in the North China Plain.