The critical limit of cadmium in three types of soil texture with shallot as an indicator plant

Heavy metals pollution in agricultural land needs to be considered. One of the heavy metals that have the potential to pollute the soil and plants is cadmium. Therefore it is necessary to anticipate the effects of cadmium pollution. The aims of this research are to obtain information on the critical limit of cadmium heavy metals in light, medium and heavy soils texture in horticultural fields, with shallots as an indicator plant. The stages of this research are adsorption studies in the laboratory and continued with pot experiment in the screen house for calibration of cadmium metals. Adsorption studies were carried out using the Langmuir Adsorption Model with the Cd concentration series. The experimental design was a complete randomized design with 7 treatments and three replications. Each pot is filled with 9 kg of soil and planted with shallots for 2 months. The results showed that the buffering capacity of light texture (Magelang), medium texture (Jaken) and heavy texture (Demak) soils of cadmium metal were 384.62 mg/kg, 120.48 mg/kg and 1,557.69 mg/kg respectively. The critical limit of cadmium metal in light textured soils is 5.33 mg/kg, medium textured 6.33 mg/kg, and heavy textured 9.29 mg/kg. Soils with high clay content have higher the critical limit values compared to soils with low clay content.