Fertilization Methods Effect Spring Wheat Yield and Soil CH4 Fluxes in the Loess Plateau of China

Dryland agricultural soils are recognized as significant sites of methane (CH₄) absorption, making them integral to the global CH₄ budget. Nitrogen fertilization is commonly used by growers in these regions to obtain optimal wheat yields, but it is unclear how various methods may affect CH₄ absorption. Therefore, we conducted two years of field studies in the rain-fed agricultural experimental station in the semi-arid Loess Plateau in northwest China to test how four fertilization methods altered different crop and soil characteristics. Plots consisted of a popular spring wheat variety treated with either no fertilizer (CK), nitrogen fertilizer (N), organic manure (M), or a combination of nitrogen and organic manure (NM). We analyzed the effects each fertilization methods had on both yield and soil CH₄ flux. The results indicated that these soils act as a net sink of CH₄. The NM treatment significantly increased wheat yield, while the N treatment significantly reduced CH₄ absorption. Furthermore, soil CH₄ absorption under each treatment had a clear temporal pattern, which peaked during the flowering stage. Our principal component analysis and linear regression analysis illustrated how CH₄ fluxes were significantly positively or negatively correlated with soil total nitrogen, nitrate nitrogen, and temperature (P < 0.05), potentially explaining 40% of the CH₄ variability. In conclusion, our results indicate that the co-application of nitrogen and organic manure can both support optimal wheat yield and effectively reduce the risk of CH₄ emissions.