Optimizing the Ratio of Conventional Urea to Polyurethane-Coated Urea via Single Basal Application Improves Growth, Nitrogen Use Efficiency and Economic Return of Tillering Mustard
This study evaluated the effects of a single basal application of controlled-release blended fertilizer (CRBF) with different ratios of conventional urea to polyurethane-coated urea on tillering mustard (Brassica juncea var. multiceps). A field experiment was conducted with six treatments: no nitrogen (CK), conventional urea split application (U), and four CRBF ratios with coated urea proportions of 30% (CRU1), 50% (CRU2), 70% (CRU3), and 100% (CRU4). The CRU3 treatment (30% conventional urea + 70% coated urea) achieved the best comprehensive performance, significantly increasing mustard yield, nitrogen recovery efficiency, and economic returns. Soil physicochemical properties, enzyme activities, and microbial community structures (16S rRNA for bacteria and ITS for fungi) were analyzed. The 18 soil samples (0-20 cm depth) were collected at harvest from three replications of six treatments. The sequencing data will be used to elucidate the mechanisms by which CRBF application influences soil microecology and crop productivity.