Effects of N Fertilizer Type and Application Method on Broccoli Yield, Quality, and NUE via 15N Tracer

The purpose of this study was to evaluate the effects of different nitrogen sources and application methods on the growth and yield quality of broccoli plants (Brassica oleracea L. var. italica). The treatments included ammonium sulfate (20%), 15N-labeled fertilizer. and organic mulch derived from Crotalaria juncea L. residues, which were either mixed into the soil or applied as mulch on the soil's surface. The results indicated that broccoli plants treated with organic mulch applied to the soil surface (T1) and 15N-labeled fertilizer, whether used as mulch or incorporated into the soil (T3 and T4), significantly enhanced nitrogen use efficiency (NUE), nitrogen derived from fertilizer (NDFF), leaf nutrient content (N, P, K, S, Fe, Zn, and Mn), head quality (including head area, head fresh weight, dry weight, canopy area, total flavonoids, total phenols, and sulforaphane content), and vegetative growth (plant height, fresh weight, dry weight, and SPAD readings). This study suggests that the application of green mulch is cost-effective and environmentally sustainable strategy for improving broccoli growth performance, head yield and quality.