Characteristics of soil organic carbon and total nitrogen storages for different land-use types in Central Yunnan Plateau

Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land, forestland, grassland, farmland, and bare land in the Dachunhe watershed of Jinning District, Kunming City, Yunnan Province, China. The effects of the soil organic carbon, total nitrogen stratification ratio, soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed. The results show that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed are statistically significant(P<0.05). The organic carbon and total nitrogen stratification ratio SR1 of garden land soil are 38.5% and 25.3%, respectively, which are higher than SR2. The soil organic carbon and total nitrogen stratification ratio SR2 of different land-use types are greater than SR1. There are statistically significant differences in the SR2 soil organic carbon and total nitrogen stratification ratios(P<0.05). Soil organic carbon and total nitrogen storage of diffe-rent land-use types gradually decrease with increasing soil depth, with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer. Soil organic carbon and total nitrogen sto-rage at the same soil depth are significantly different(P<0.05). Soil organic carbon and total nitrogen storage in the garden land are greater than those in the other land-use types. Soil organic carbon and total nitrogen storage in 0-20 cm garden land are 4.96 and 3.19 times than those in bare land, respectively; soil organic carbon and total nitrogen storage are explained by 93.66% and 1.53% in redundancy analysis RDA1 and RDA2, respectively. All physicochemical factors except Available Phosphorus and pH are statistically significance with carbon and nitrogen storage(P<0.05). Soil cationic exchange capacity, Available Phosphorus, C/N ratio, and Moisture Content are positively correlated with organic carbon and total nitrogen storage. In contrast, soil Bulk Density is negatively correlated with organic carbon storage and total nitrogen storage. Available Phosphorus, C/N ratio, and Moisture Content are the main factors promoting soil organic carbon and total nitrogen accumulation.