Objective Excessive and unbalanced fertilization are common in the spring soybean production of Heilongjiang Province, leading to low fertilizer utilization efficiency and production profits in that area. We constructed a soybean nutrient expert system based on the yield responses and agronomic efficiencies, and tested its yield and economic effect through field experiments.

Methods From 2021 to 2024, 47 field verification experiments were carried out in the main production area of spring soybeans in Heilongjiang Province. All the experiments contained the following six treatments: fertilization recommended by the soybean nutrient expert system (NE), elite N fertilizer of NE (NE-N), elite P fertilizer of NE (NE-P), elite K fertilizer of NE (NE-K), farmers’ habitual fertilization (FP), and fertilizer recommendation based on soil testing (ST). The soybean yield, nutrient utilization efficiency and economic benefit responses were investigated at harvest.

Results In the main soybean production area of Heilongjiang, the above-ground N, P and K requirements of spring soybeans for producing 1 t of soybean grain were 54.8, 7.9 and 20.5 kg, respectively; the average yield responses of N, P and K fertilizer were 421.4, 395.8 and 418.3 kg/hm², respectively; the average agronomic efficiencies of N, P and K fertilizers are 9.5, 8.1 and 9.1 kg/kg, respectively; the average fertilizer use efficiencies of soybean for N, P, and K were 37.3, 18.9, and 24.0%, respectively. Compared with FP, the soybean yields and economic benefits under NE and ST treatments both increased significantly. The yields rose by 12.6% and 14.2% respectively, while the economic benefits improved by 7.1% and 6.7% respectively. Additionally, the amount of fertilizer applied was substantially reduced. Compared with ST, the yield of soybeans treated with NE increased by an average of 5.1%, and the economic benefit increased by an average of 7.1%.

Conclusion A large number of field trials proved the priority of NE-based fertilization recommendation over the conventional method based on soil testing in increasing yield, economic benefits, and nutrient utilization efficiency of spring soybeans, so is a available soybean fertilization recommendation technique for the actual production of soybean production.