Objective This study investigated the effects of chemical fertilizer reduction and organic manure nitrogen (N) equivalent replacement of chemical fertilizer N on potato N uptake and yield, providing a theoretical basis for the implementation of the national zero-growth strategy of chemical fertilizers.

Method Taking 'Yunnan Potato 1418' as the test material, five treatments were set up, including no fertilization (CK), single application of chemical fertilizer (CF), organic fertilizer N replacing 20% of chemical fertilizer N (MF₁), organic fertilizer N replacing 40% of chemical fertilizer N (MF₂) and organic fertilizer N replacing 60% of chemical fertilizer N (MF₃). The field experiment of potato fertilization effect was carried out in 2023 and 2024. In the five treatments, except for CK, the nutrient inputs of N, phosphorus (P) and potassium (K) in other treatments were the same. During the growth period of potato, the physical and chemical properties of rhizosphere soil, dry matter and N accumulation in different parts of the plant were measured, and potato yield and commercial potato rate were measured at maturity and the economic benefits of potato, fertilizer utilization rate and N surplus were calculated.

Result The results showed that the potato yield of MF₁ and MF₂ treatments reached the highest and relatively stable in 2023 and 2024. Compared with CK and CF treatments, organic fertilizer N replacing chemical fertilizer N treatments MF₁ and MF₂ promoted the dry matter accumulation and N accumulation of potato tubers and whole plants, thus increasing the total income of potato production, and increased the content of available N and available K and reduced the soil N surplus. Compared with CF treatment, the N accumulation of potato tubers increased by 1.89% ~ 5.38% and 3.85% ~ 21.69% at maturity stage of MF₁ and MF₂, and the N accumulation of whole plant increased by 5.41% ~ 6.09% at maturity stage of MF₁ treatment in two years. Potato yield was significantly positively correlated with various fertilizer utilization rates and significantly negatively correlated with soil N surplus.

Conclusion Soil nutrient availability coincided with the characteristics of potato N nutrient uptake when 20% ~ 40% of organic fertilizer N was applied in place of chemical fertilizer N on farmland with high fertility soils in the Erhai Basin. It can not only ensure the need for N during potato tuber formation, but also promote the N absorption and accumulation during potato tuber expansion and maturity, thereby increasing potato yield and fertilizer utilization rate, which is the best fertilization method to achieve efficient potato planting.