LAUSR

BACKGROUND Deep fertilization is effective for improving crop yield and fertilizer use efficiency. However, its impact on mechanized direct-seeded rapeseed and the optimal fertilization depth were poorly understood. A field experiment was conducted to evaluate the fertilization depth effect on mechanized direct-seeded rapeseed growth. Five treatments were designed: surface broadcast fertilizer (CK), no fertilization, and fertilizer banded placement at soil depths of 5 (D5), 10 (D10), and 15 cm (D15). RESULTS Compared with CK, deep fertilization generally increased seed yield and partial factor productivity (PFP) by 11.0%, agronomic efficiency (AE) by 22.7%, and recovery efficiency (RE) by 79.2% due to the increase of root mass density (16.8%), plant height (8.6%), height of the first branch (10.6%), stem diameter (22.4%), shoot biomass (16.1%), and shoot N (35.7%), P (29.7%), and K (26.2%) uptake. The D10 had the highest seed yield, oil yield, fertilizer use efficiency, and economic benefits at different fertilization depth treatments. Compared with D5 and D15, D10 increased seed yield by 5.4% and 46.0%, oil yield by 7.7% and 50.5%, PFP by 5.4% and 46.0%, AE by 9.0% and 99.5%, RE of N by 48.9% and 34.9%, RE of P by 83.1% and 38.0%, and RE of K by 57.5% and 32.5%, respectively. The economic benefits in D10 were 867.31 and 4864.23 CNY ha-1 higher than D5 and D15, respectively. CONCLUSION Considering rapeseed growth and its economic benefits, this study shows that 10 cm is an appropriate deep placement depth with regard to mechanized direct-seeded winter rapeseed production. This article is protected by copyright. All rights reserved.