Phytoaccumulation of Cadmium in Leafy Vegetables Grown in Contaminated Soil under Varying Rates of Compost and Phosphate Fertilizer Application

Cadmium (Cd) contamination in agricultural soil is a global issue of concern because of its potential transfer to the human body through food chain interactions. Phosphate fertilizers used in the agricultural soils contain a high concentration of Cd. Composts are good sources of phosphorus, thus mixing of compost with phosphate fertilizer could reduce the total phosphate fertilizer use and subsequent Cd enrichment in agricultural soils. However, the optimum mixing ratio of compost and phosphate fertilizer is of paramount importance to obtain the desired outcome. In this study, experimental pot trials were performed to assess plant growth and Cd accumulation in two leafy vegetables, red amaranth (Amaranthus cruentus) and water spinach (Ipomoea aquatica), grown in Cd-contaminated loamy sandy soil under varying rates of compost and phosphate fertilizer application, either alone or in mixture. The study revealed that application of compost in combination with phosphate fertilizer is more effective from both environmental and economic perspectives rather than the application of compost alone, wherein 10 t/ha compost in combination with 40 kg/ha phosphate fertilizer was found as the best treatment for reducing Cd phytoaccumulation in both vegetable species and increasing the plant growth. Moreover, this optimum mixing ratio of compost and phosphate fertilizer showed positive impacts on soil pH and EC. The results also observed that phytoaccumulation of Cd decreases with decreasing the rate of phosphate fertilizer application, either alone or in mixture. Moreover, further study is necessary to determine the impact of combined treatments on microorganisms influencing Cd dynamics in soils.