Objective The study focused on the effects of replacing different amounts of nitrogen (N) fertilizer by waste originated organic fertilizer on the physical, chemical and biological properties of lily planting soil, which would provide a theoretical basis for improving the issues of nutrient imbalance and character deterioration and also the safe utilization of waste resources in Lily planting soil.

Method There were 5 treatments in the field experiment, including 100% chemical fertilizer treatment (CK), combined applications of organic and inorganic fertilizers, including 25% (T1), 50% (T2), 75% (T3) and 100% (T4) of chemical N fertilizer replaced by N in organic fertilizer. The basic physical and chemical properties of soil, nutrient content, water-stable aggregates and soil protease activities were analyzed.

Result The results showed that the yield of lily bulbs in one planting year decreased with the increase of substitution amount. However, the decreases were extremely small in T1 and T2 and had no significant difference with CK. The economic benefit of T1 treatment was the highest in all substitution treatments. There was no significant difference in soil pH among different treatments. The CEC and soil organic matter showed an increasing trend. For the total nutrients, soil total N and total phosphorus (P) increased significantly in T4, and no significant difference was found among other treatments. There was no significant difference in soil total potassium (K) content among the treatments. For available nutrients, the available N content increased with the replacing amount of organic fertilizer, and those in T3 and T4 were higher than CK by 74.84% and 80.31% (P < 0.05), respectively. No significant difference was detected in hydrolytic N content among treatments. The available P showed an increasing trend, which showed an increase of 70.09% (P < 0.05) in T4 compared with CK. Soil microbial biomass N in the combined application treatments (T1, T2, T3) was slightly higher than that of 100% chemical fertilizer or 100% organic fertilizer N substitution treatment. The water-stable aggregates of < 0.25 mm accounted for the main part in each treatment (52.51% ~ 63.06%), and decreased (by 9.55% ~ 16.73%) with the increasing amount of organic fertilizer instead of N fertilizer, accordingly, the proportion of large aggregates increased. The WSAC_0.25 in treatments increased by 16.30% ~ 45.54%, MWD and GMD increased by 53.62% ~ 74.73% and 24.22% ~ 37.30% (P < 0.05) compared to CK, respectively. And the K_CTP increased by 46.69% ~ 125.3% (P < 0.05). The soil protease activities in T1 and T2 were slightly higher than that in CK, with no significance. However, it increased significantly by 39.19% and 46.67% in T3 and T4.

Conclusion The replacing part of N fertilizer by waste originated organic fertilizer on lily planting soil was beneficial to enhance the soil nutrient availability, improving its physical structure, and increasing soil protease activity to a certain extent. From the perspective of lily yield and economic benefits, the substitution amount should be less than 25%.