Effects of multiple cropping and applying green manure during the autumn fallow period on the yield,nitrogen residue and N2O emission of spring wheat
The field experiments were conducted from 2021 to 2022 to investigate the effects of multi-ple cropping and applying green manure during the autumn fallow period on the yield,soil nitrogen content and N2O emission of spring wheat in Qinghai.A total of six treatments are set up,including conventional fertilization at 100％(F100),70％(F70),0％(F0)and multiple cropping and ap-plying green manure combined with chemical fertilizer at 100％(F100+G),70％(F70+G)and 0％(F0+G).The content of nitrate nitrogen and ammonium nitrogen in the 0～100 cm soil during the seedling,flowering and harvest stages is analyzed under different treatments.The characteristics of N2O emission and wheat yield are analyzed throughout the entire growth period.The results show that the numbers of ears,grains per ear,thousand grain weight and yield of spring wheat are signifi-cantly increased(P＜0.05)with the treatment of multiple cropping and applying green manure.The treatment F70+G has the best yield increasing effect,reaching 6 025 kg/hm2.The content of nitrate nitrogen and ammonium nitrogen during the flowering and maturity stages is F70+G＞F100+G＞F70＞F0+G＞Fl00＞F0.Compared with applying chemical fertilizer alone,the application of mul-tiple cropping and green manure combined with chemical fertilizer can reduce N2O emissions,with the treatment F70+G significantly reducing N2O emission compared to the treatment F70(P＜0.05).The treatment F70+G has the lowest N2O emission intensity.Therefore,the optimal cultiva-tion method for spring wheat in Qinghai is to combine multiple cropping with green manure and 70％chemical fertilizer.
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