Abstract: 【Objective】 To clarify the effects of different fertilization methods on the growth of sweet sorghum,soil physical properties,and soil organic carbon storage in the Loess Plateau region of eastern Gansu. 【Methods】 The experiment was conducted in Jingchuan County,Pingliang City,Gansu Province. A two-factor split-plot design was used. Nitrogen fertilizer was applied as the main plot with four nitrogen levels （T0,T100,T200,T300）. Organic fertilizer was applied as the subplot and two levels were set：combined application （T0Y,T100Y,T200Y,T300Y） and non-application. Naturally growing native alfalfa was set as the control （CK）. The effects of different fertilization treatments on sweet sorghum growth indicators,fresh biomass yield,root fresh weight,root dry weight,survival rate,and soil bulk density,total porosity,density,and organic carbon storage in the 0-80 cm soil layer were analyzed. 【Results】 Compared with T0 treatment,combined application of organic and inorganic fertilizers significantly affected plant height,maximum leaf length,and maximum leaf width of sweet sorghum. Among them,the T200Y treatment had the highest plant height of 412.60 cm; the T100Y treatment had the longest maximum leaf length of 112.91 cm; and the T300Y treatment had the widest maximum leaf width of 9.70 cm. The fresh biomass yield,root fresh weight,root dry weight,and survival rate of the T200Y treatment were the highest,with values of 110.66 t/hm²,16.34 t/hm²,6.03 t/hm²,and 94.00%,respectively,and all were significantly higher than other treatments （P<0.05）. Compared with CK and T0 treatments,combined application of organic and inorganic fertilizers decreased soil bulk density and density,and increased total porosity. Under the T200Y treatment,the soil bulk density and soil density in the 0-20 cm layer were lower,and the total porosity was higher,with values of 1.12 g/cm³,2.28 g/cm³,and 53.33%,respectively. The T200Y treatment had the highest soil organic carbon storage in the 0-20,20-40,and 40-60 cm soil layers,with values of 30.96,27.54,and 24.25 t/hm²,respectively,which were increased by 5.0%,3.7%,and 1.1% compared with T0 treatment. 【Conclusion】 Under the treatment of 200 kg N/hm² combined with organic fertilizer,the fresh biomass yield,root fresh weight,root dry weight,and survival rate of sweet sorghum are significantly improved,the soil structure is effectively improved,and the soil organic carbon storage is increased,making it suitable for promotion and application in sweet sorghum cultivation.

Key words: Fertilization, Sweet sorghum, Growth, Soil physical properties, Soil organic carbon storage