Impact of Organic Amendments on Black Wheat Yield, Grain Quality, and Soil Biochemical Properties

This study investigated the effects of organic amendments (straw return, organic fertilizer, biochar, and their combinations) on grain yield, quality, and soil biochemical characteristics in black wheat. A two-year field experiment (2022–2024) was conducted with five treatments: F (conventional fertilization), FS (F + full straw return), FO (F + 3 t/ha organic fertilizer), FB (F + 3 t/ha biochar), and FSOB (F + full straw + 3 t/ha organic fertilizer + 3 t/ha biochar). FSOB achieved the highest yield, increasing by 17.3% over F due to a higher spike number and 1000-grain weight. Grain protein increased by 9.0% and 9.4% under FS and FO, respectively. Straw addition also raised gluten by 6.8%. Soil analysis revealed that integrated organic management significantly increased the contents of organic matter (by 23.1%), total nitrogen (by 46.0%), and available phosphorus (by 73.5%) in the 0–20 cm soil layer. It also promoted beneficial microbial taxa, including Actinobacteria (+11.2%) and Proteobacteria (+0.6%), compared to conventional fertilization. These findings suggest that strategic integration of organic amendments can enhance black wheat productivity and grain quality by improving soil fertility and microbial functionality, thereby supporting sustainable cropping systems.