Effects of Straw and Nitrogenous Fertilizers on the Soil Aggregate Stability and Quality in Subtropical Regions of China

To optimize the utilization of straw resources and devise appropriate nitrogen fertilizer application strategies, this study centers on enhancing soil productivity while boosting double-season maize yield in Guangxi, ultimately aiming to foster sustainable agricultural development while pursuing yield. It was a five-year split-plot study where the main plots were straw return and traditional planting treatments, and the subscript were 0 and 250 kg ha^− 1 N fertilizer applications. The soil physicochemical property were determined in 0–20 cm and 20–40 cm soil depth. Furthermore, soil samples were fractionated into different size aggregates, followed by a measurement of aggregate distribution and nutrient content. Our findings revealed a distribution trend of large macro-aggregates (> 2000 μm) > small macro-aggregates (250–2000 μm) > micro-aggregates (53–250 μm), with a notably small proportion of aggregates < 0.053 μm. Specifically, 250 kg ha^− 1 nitrogen application under straw return (SRN250) demonstrated an enhancement in soil aggregate organic carbon (SOC) content, leading to improved soil physical attributes and stability within the 0–40 cm soil depth. Changes in aggregate total nitrogen, total phosphorus, and total potassium were predominantly observed in the 0–20 cm soil depth. Furthermore, a positive correlation was established between SOC and aggregate stability. The experimental results show that the SRN250 management practice can not only increase maize yields but also enhance the soil fertility within five years. Additionally, the study highlights the crucial role of SOC content in facilitating aggregate formation and increasing large macro-aggregates distribution, indicating the importance of maintaining SOC content for soil health and sustainability.