Comparative Analysis on Effect of Wheat Straw and Its Biochar Amendment on Net Global Warming Potential Under Wheat-Maize Rotation Ecosystem in the Guanzhong Plain

Abstract

In order to compare the differences in carbon sequestration and greenhouse gas mitigation between straw and straw-derived biochar amendment, a field experiment was conducted with simultaneous measurement of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions, crop yield, soil organic carbon (SOC) content and net global warming potential (NGWP) in a wheat-maize rotation cropping system from the loess plateau of China. Five treatments were included:control (no straw incorporation, no straw-derived biochar amendment and no fertilization, CK), fertilization (no straw incorporation and no straw-derived biochar amendment, F), straw with fertilization (wheat straw incorporated at 8 t·hm-2, FS), low straw-derived biochar (8 t·hm-2) with fertilization (FBlow) and high straw-derived biochar (16 t·hm-2) with fertilization (FBhigh). Wheat yield increased by 30.9%, 66.3% and 36.6% under FS, FBlow and FBhigh treatment, as compared to the F treatment, respectively. However, maize yield decreased by 14.1%, 18.0% and 24.6% under FS, CK and FBhigh treatment as compared to the F treatment, respectively. There was no significant difference between FBlow and F treatment. Annual CO2 emission increased by 60.2% under FS treatment, but decreased by 14.4% under FBhigh treatment as compared to the F treatment, respectively. Annual N2O emission decreased by 27.6% and 38.7% under FBlow and FBhigh treatment as compared to the F treatment, respectively. However, no significant difference was observed under straw application. Overall, the NGWP decreased by 24.13 and 58.44 t·hm-2 under FBlow and FBhigh treatment as compared to the F treatment, respectively. And the NGHGI decreased by 1.78 and 5.06 t·t-1 under FBlow and FBhigh treatment as compared to the F treatment, respectively. In summary, we conclude that the fertilization with 16 t·hm-2 biochar amendment can be used as an effective management to improve the crop yield and reduce the net global warming potential under the wheat-maize rotation system.