Effects of Soil Properties on the Accumulation and Bioavailability of Copper in the Orange Growing Soil in Cao Phong, Hoa Binh

This study focuses on investigating the crucial influence of some soil properties on the adsorption capacity and fractions of Cu in the citrus-growing soil in Cao Phong district, Hoa Binh province. Batch experiments were conducted by adding 0, 100, 500, and 1000 mgCu/L to soil samples with different characteristics. In the 100 mgCu/L added experiment, we found the highest Cu adsorption rate (> 93.76%) in soil samples with loamy texture, high pHKCl, %OC, and low nutrients. Conversely, the lowest Cu adsorption rates (78.32-79.23%) were observed in soil samples with lower pH, and higher %OC and nutrient availability. Noting that the total adsorbed Cu has a negative correlation with the amount of Cu added to the soil, gradually decreasing from (78.32-95.67%) to (26.67-34.19%) and the lowest (22.48-28.56%) in soil samples with the added levels of 100, 500, and 1000 mgCu/L, respectively. In soil samples with total Cu > 200 mg/kg, pHKCl 4.79-5.32, and OC 1.34-2.06%, the bioavailable Cu ranged from 2.29-4.29 mg/kg, which is safe for the soil environment and ecosystem, and sufficient as a micronutrient for citrus plants. It is necessary to find the best solutions for managing Cu-polluted soils.