Study on Variation Characteristics of Soil Effective Boron and Cation Exchange Capacity in Dachunhe Watershed

In order to improve soil fertility conservation capacity and build a reasonable tilth structure, the research object of this study is forest land, garden land, grass land, arable land and bare land in the Dachun River watershed of Kunming City, Yunnan Province. Fixed depth method(FD) and equivalent mass method(ESM) were used to calculate soil effective boron reserves, and Franzluebbers calculated the stratification rate of soil effective boron(EB) and cation exchange capacity(CEC), analyze the variation characteristics and influencing factors of soil effective boron and cation exchange capacity with depth. The results show that soil effective boron varied significantly with soil depth(P < 0.05), forest land and garden land decreased with the increase of depth; grass land, arable land and bare land increase with depth; the stratification rate SR₂ of soil effective boron and cation exchange capacity in forest land is higher than SR₁; the content of soil cation exchange capacity significantly increases or decreases with the increase of soil depth; cations adhere to the soil and lose, the content of soil cation exchange capacity decreased with the increase of soil depth; organic matter(OM), total nitrogen(TN), water content(MC) and bulk density(BD) were significantly correlated with soil EB and CEC(P < 0.05). OM, TN, and MC of different land use types were positively correlated with soil EB and CEC, while BD was negatively correlated with soil EB and CEC. The fertilizer retention capacity of forest land and garden land is higher than that of grass land, arable land, and bare land, with the best fertilizer retention capacity of 0–20 cm; grass land, arable land, and bare land with a thickness of 40–60 cm have the best fertilizer retention capacity. Vegetation coverage and soil erosion are the main physical factors affecting soil EB and CEC, while OM, TN, MC and BD are the main chemical factors affecting soil EB and CEC. It is necessary to construct a reasonable cultivation layer to improve the ability of water and fertilizer conservation.