Objectives Chinese cabbage (Brassica rapa L. ssp. pekinensis) is cultivated extensively across various regions in China. We have developed an intelligent nutrient expert recommendation system for fertilizer application in Chinese cabbage production, based on yield response and agronomic efficiency. This system will provide simple and reliable fertilization schemes for Chinese cabbage production under different soil and climatic conditions.

Methods Data were sourced from field fertilizer experiments conducted by the China Program of the International Plant Nutrition Institute and our research team in major Chinese cabbage production areas from 2000 to 2023, as well as publicly published academic articles retrieved from the China National Knowledge Infrastructure (CNKI) database during this period using keywords such as “Chinese cabbage”, “Chinese cabbage + yield”, “Chinese cabbage + nutrient uptake”, and “Chinese cabbage + fertilizer use efficiency/recovery efficiency”. Based on “field fertilizer experiments” and “open-field Chinese cabbage experiment”, we screened yield data 2809 pieces, N, P, and K uptake data 667, 505, and 514 pieces, and N, P, and K yield response data 153, 113, and 264 pieces, respectively. The QUEFTS model was used to simulate and analyze the optimal nutrient demand characteristics for different target yields of Chinese cabbage. Combined with computer technology, an expert system for nutrient management in Chinese cabbage was developed. In 2023, six sets of field experiments were conducted in major Chinese cabbage production areas in Shandong and Hebei. Each set included six treatments: Nutrient Expert system-based fertilizer recommendation (NE), farmer’s practice (FP), soil testing-based fertilizer recommendation (ST), and NE without N, P, or K application, respectively. The Chinese cabbage yield, economic benefits, and nutrient use efficiency were analyzed.

Results The average yield of open-field Chinese cabbage in China from 2000 to 2023 was 86.0 t/hm², with N, P, and K nutrient uptake amounts of 178.5, 40.1, and 225.4 kg/hm², respectively. Based on QUEFTS model analysis, the required N, P, and K nutrient of Chinese cabbage were 1.64, 0.33 and 2.21 kg/t, respectively. There was a significant quadratic relationship between yield response and agronomic efficiency (P<0.05), with correlation coefficients of 0.743 for N, 0.753 for P, and 0.806 for K. Field experiment results showed that the N, P₂O₅, and K₂O application rates in NE treatment was 8.4%, 39.3%, and 6.1% less than in FP, and was comparable to that in ST treatment. Compared to ST and FP treatments, NE treatment increased Chinese cabbage yield by 2.0% and 7.8%, improved economic benefits by 2.6% and 13.4%, respectively, and increased N recovery efficiency by 34.9% and 28.6%, and enhanced K partial factor productivity by 13.8% and 21.7%. The N and P partial productivity of NE treatment was comparable to that of ST treatment, but higher than that of FP treatment, with increases of 16.1% and 94.4%, respectively.

Conclusions Compared to conventional soil testing-based fertilizer recommendation technology, the Nutrient Expert system for Chinese cabbage, which is based on yield response and agronomic efficiency, provides fertilizer recommendations tailored to different production conditions. This system not only optimizes fertilizer usage but also enhances Chinese cabbage yield, economic benefits, and fertilizer use efficiency. It fully demonstrates that the Nutrient Expert system for Chinese cabbage is a widely adaptable intelligent fertilizer recommendation method suitable for Chinese cabbage cultivation in different regions and at various scales in China.