Commercial organic fertilizer substitution increases wheat yield by improving soil quality.

Traditional organic fertilizer substitution is an effective measure for increasing crop yield and soil quality while reducing chemical fertilizer input. However, the effects of commercial organic fertilizer substitution (COFS) on soil quality and wheat yield, and the underlying mechanisms, are unknown. In this study, agricultural fields with low fertility (LF) and high (HF) fertility soils were selected for a two-year (2018-2019) field experiment in the oasis region of Northwest China. Three fertilization treatments with three replications (no fertilization, CK; local conventional chemical fertilizer application, LCF; and 20 % of inorganic nitrogen (N) was substituted by commercial organic fertilizer, COFS) were established to study the effects of COFS on wheat growth, yield, nutrient-use efficiency and soil quality. The results showed that compared with LCF in 2018 and 2019, COFS in LF and HF promoted wheat growth, improved nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE), and increased yield (by 1.52 %-3.05 % and 1.16 %-1.39 %) and soil quality (by 15.09 %-28.63 % and 22.53 %-64.82 %) by improving most soil indicators (e.g., soil organic matter (SOM) and available nutrients). Moreover, SOM and available nutrients significantly affect soil quality and wheat yield, which can monitor changes in soil quality and wheat yield. In conclusion, our study revealed that the mechanism of COFS in HF and LF increased wheat yield by improving soil quality. COFS is recommended for agricultural production, but its continuous application requires monitoring changes in SOM and available nutrients to adjust fertilization to guarantee soil quality and crop yield. This study provides guidance for the scientific application of COFS to improve farmland productivity and soil quality and helps to promote healthy and sustainable agricultural development.