The combination of microbial agent, organic fertilizer, and silica powder enhances oat yield and quality through regulating rhizosphere processes

Aims Soil salinization is a global challenge for sustainable agricultural development. Composite modifiers have the potential to boost the agricultural productivity of salinized soils. However, it’s still unclear whether it outperforms single modifiers in regulating rhizosphere soil properties, microbial communities, and forage yield and quality of different oat varieties ( Avena sativa L.) and the mechanisms. Methods In this field experiment in 2023–2024 in the arid western China, five modifier treatments, namely CK (control group without any modifier), TJ (microbial agent), TF (organic fertilizer), TG (silica powder), and TJFG (microbial agent + organic fertilizer + silica powder), were designed for two oat varieties (TY 60, Tianyan 60; MST 2, Musite 2). Then, their effects on salinized soil properties, rhizosphere microbial communities, and the interaction between soil nutrient cycling and microbial composition were explored. Results The crude protein (CP) content of the two oat varieties peaked under the TJFG treatment. The rhizosphere soil NH 4 + -N, available phosphorus (AP), available potassium (AK), organic matter (SOM), and water content (SWC) of the TJFG treatment were significantly higher than those of CK, while the soil pH and NO 3 − -N content were significantly lower. In addition, the AP content of the TJFG treatment was 70.17, 44.91, and 66.93% (average over 2 years) higher than that of the TJ, TF, and TG treatments, respectively. Conclusion The application of TJFG improved the diversity of bacterial and fungal communities as well as the activities of phosphatase (ATP), urease (UE), and catalase (CAT), thereby promoting soil nutrient transformations and enhancing soil fertility, oat yield, and quality. Chloroflexota and Ascomycota were the key microbial phyla to regulate oat yield. Organic matter, AK, AP, and CAT activity were the main soil factors affecting yield. Overall, MST 2 has greater growth potential and more value for promotion and application than TY 60. This study provides an important reference for salinized land use, ecological health maintenance, and sustainable agricultural production in arid regions.