Abstract:

In order to explore the effect of partial replacement of chemical fertilizer by organic fertilizer on the ecological stoichiometric characteristics of soil carbon,nitrogen and phosphorus in the Loess Plateau of Eastern Qinghai,a field experiment was conducted with continuous cropping of potato(Qingshu 9).This field experiment was established in 2022 with five treatments,i.e.no fertilizer(CK),100% chemical fertilizer(T1),30% organic fertilizer+70% chemical fertilizer(T2),50% organic fertilizer+50% chemical fertilizer(T3),and 70% organic fertilizer+30% chemical fertilizer(T4).Soil contents of organic carbon,total nitrogen,total phosphorus,alkali-hydrolyzable nitrogen,available phosphorus,microbial biomass carbon,nitrogen,phosphorus and soil-microbial biomass ecological stoichiometry were determined.The results showed that compared with 2022,the contents of soil organic carbon,total nitrogen,total phosphorus,alkali-hydrolyzable nitrogen,available phosphorus and microbial biomass carbon,nitrogen and phosphorus in each fertilization treatment in 2023 showed an increasing trend,while the CK treatment showed a decreasing trend.Among different soil layers,the content of each index gradually decreased with the increase of soil depth.Among different treatments,according to the content of each index,the order was T3>T4>T2>T1>CK.In the 0—30 cm soil layer,the contents of soil organic carbon,total nitrogen,total phosphorus,alkali-hydrolyzable nitrogen,available phosphorus and microbial biomass carbon,nitrogen and phosphorus under T3 treatment were 6.88%,17.65%,17.88%,84.71%,77.01%,65.67%,80.07%,54.91% higher than those of CK,respectively.The soil C∶N and C∶P in each soil layer were the highest in the CK treatment.Among the four fertilization treatments,soil C∶N,microbial biomass C∶N and C∶P were the lowest in the T3 treatment.In addition to the 0—10 cm soil layer in 2023,the soil C∶P in each soil layer was also the lowest in T3,while the microbial biomass N∶P in the T1 treatment was the lowest among all fertilization treatments.Soil C∶N and C∶P increased with soil depth.Correlation analysis showed that organic carbon,total nitrogen,total phosphorus,available nitrogen,available phosphorus and microbial biomass carbon,nitrogen and phosphorus were significantly positively correlated with each other.In summary,the substitution of organic fertilizer for chemical fertilizer can not only change the soil nutrient and soil microbial biomass content,but also change the soil ecological stoichiometry characteristics,and the treatment with 50% organic fertilizer+50% chemical fertilizer has the best effect.

Key words: Organic fertilizer partially replaces chemical fertilizer, Soil, Microbial biomass, Ecological stoichiometry, Qingdong Loess Plateau

CLC Number: 

• S158

• S963.91