An intelligent fertilizer recommendation method for winter rape based on yield response and agronomic efficiency

Objectives Intelligent fertilizer recommendation based on yield response and agronomic efficiency have demonstrated convincing results for crops across various regions and species in China. This study aimed to develop a fertilization recommendation approach tailored to winter oilseed rape (Brassica napus L.) in China, focus on enhancing production efficiency while reducing environmental risks.

Methods We collected field fertilizer trial data for winter oilseed rape published during 2000 to 2023, using keywords “oilseed rape”, “oilseed rape + yield”, “oilseed rape + nutrient uptake”, and “oilseed rape + fertilizer use efficiency”. The QUEFTS model was employed to analyze nutrient uptake characteristics and to optimize agronomic parameters including yield response and agronomic efficiency. And then a nutrient expert recommendation system (NE) tailored for winter oilseed rape was developed. From 2021 to 2023, 65 field validation trials were conducted across Hubei Province, with three fertilization treatments in each trail: Nutrient Expert recommendation (NE), farmers’ conventional practice (FP), and soil testing recommendation (ST). Crop yield, nutrient use efficiency, and economic benefits of oilseed rape production were investigated.

Results According to the QUEFTS model, producing 1 ton of winter oilseed rape seeds required 43.5 kg N, 11.0 kg P, and 44.6 kg K in the aboveground biomass. the average yield responses to N, P, and K fertilization were 1.08, 0.63, and 0.42 t/hm², respectively, with corresponding agronomic efficiencies of 6.26, 8.24, and 4.97 kg/kg. The relationships between fertilization and yield were quantified as: y=−0.8043x²+6.9351x−0.0648 for N, y=−2.6103x²+16.139x−0.408 for P, and y=−3.0654x²+14.031x−0.1571 for K. Compared to the ST treatment, the NE recommendation reduced N application by 20 kg/hm², increased P₂O₅ by 7 kg/hm², and maintained a similar K₂O rate. As a result, NE decreased fertilizer costs by 201 yuan/hm², increased yield and net profit by 0.11 t/hm² and 898 yuan/hm²on average, and improved agronomic efficiencies of N and K fertilizers by 1.39 kg/kg and 2.83 kg/kg, respectively.

Conclusions The intelligent fertilization recommendation system tailored to winter oilseed rape production in China outperformed other methods in balancing and reducing fertilizer cost, increasing fertilizer nutrient use efficiency, oilseed rape yield and profits. It offers a practical and efficient solution for sustainable oilseed rape production.