[Effects of Biochar and Organic Fertilizer on Saline-alkali Soil N O Emission in the North China Plain].

Based on the winter wheat-summer maize rotation field experiment, the effects of biochar and organic fertilizer on saline-alkali soil NO emissions in the summer maize season were studied in Binzhou in the Shandong Province to provide a theoretical basis for reducing NO emissions from saline-alkali soil. The experiment includes six treatments with three replications:CK[N:0.2 t·(hm·a), PO:0.12 t·(hm·a), KO:0.2 t·(hm·a)], C1[5 t·(hm·a)biochar], C2[10 t·(hm·a) biochar], C3[20 t·(hm·a) biochar], M1[7.5 t·(hm·a) organic fertilizer], and M2[10 t·(hm·a) organic fertilizer]. The same nitrogen, phosphorus, and potassium fertilizer was applied for each treatment. The results showed that the dynamic trend of the soil NO fluxes among different treatments were similar. The peak NO emissions occurred after fertilization (base fertilizer and topdressing). The NO cumulative emission fluxes accounted for nearly half of the emissions during the whole growth period, and the NO emissions of the C1, C2, and C3 treatments were lower than that of CK after fertilization. Compared with CK, the NO cumulative emissions from C1 and C2 were reduced by 45.3% and 31.6%, respectively, but C3, M1, and M2 increased by 17.3%, 37.4%, and 27.6%, respectively. Biochar and organic fertilizer both affected NO emission fluxes. Applying biochar can reduce NO emissions, while organic fertilizer can increase NO emissions. In summary, biochar has a great advantage in reducing NO emissions in the farmland.