Objectives The application method of new controlled-release urea (CRU) and stable nitrogen fertilizer (SF) combined with “4R” fertilization principle and their effects on soybean were studied by a field experiment, to provide scientific basis for the efficient application of new fertilizers.

Methods Soybean field experiments were conducted at Minzhu Experiment Base of Heilongjiang Academy of Agricultural Sciences from 2023 to 2024. In 2023, the treatments included conventional fertilization (FP, farmer practice), recommended fertilization (NE, recommendation by the Nutrient Expert system), CRU at shallow application of 6−8 cm (CRU8) and deep application of 13−15 cm (CRU15), and SF at shallow application of 6−8 cm (SF8) and deep application of 13−15 cm (SF15). In 2024, the two shallow application treatments were replaced by deep application under reducing 20% of N input (CRU80%, and SF 80%), NE treatment was split into no-N control (CK) and NE, making seven treatments in total. Plant biomass and N accumulation, soil mineral N, and field N accumulative release rate of CRU during soybean growth period were analyzed; soybean yield, economic benefit, and N use efficiency (NUE) were calculated at harvest stage.

Results The test CRU released 42.1% and 83.0% of total N in 37 and 68 days of period, respectively, the release rate was 15−35 days earlier than the time required by soybean to reach the same N accumulative rate. In 2024, the soil NO₃⁻-N and NH₄⁺-N content in CRU and SF treatments were lower than in NE and FP at the seedling stage, but they kept increasing gradually and reached peaks at the podding/flowering stages; while the soil NO₃⁻-N and NH₄⁺-N in NE and FP start to decrease gradually with the growth period. The soil NO₃⁻-N and NH₄⁺-N in CRU80% and SF80% were lower than those in CRU and SF treatments at most of growing stages. The fertilizer inputs in NE, CRU, SF, CRU80%, and SF80% treatments were the same, which were 37.3%−56.3% less than FP treatment, so the fertilizer costs were reduced by 473−549 yuan/hm². As the seed yields of NE, CRU, SF, and CRU80% were similar with SF, the net profit increased 614−1692 yuan/hm², and SF exhibited significantly higher net profit. The nitrogen agronomic efficiency was the highest in SF, followed by CRU and CRU80%, which were significantly higher than NE, and CRU80% achieved the highest N use efficiency.

Conclusions The fertilization based on the 4R principle (NE) is effective to increase the soybean yield and nitrogen use efficiency, relative to farmer’s practices. Replacing the urea with controlled-release or stable nitrogen fertilizer under one-basal-application at 15 cm depth beside the soybean roots could maintain more fitted soil inorganic nitrogen content throughout the entire growth period of soybean, and achieve comparable soybean yield and fertilizer efficiency, this benefit effect could be achieved even under condition of further 20% of nitrogen fertilizer reduction by controlled-release nitrogen fertilizer. Therefore, the one-time deep application of the new type fertilizers can realize simple and efficient fertilization of soybeans.