Impact of agrochemicals application on lead and cadmium concentrations in shallot fields and their remediation with biochar, compost, and botanical pesticides

Abstract

Abstract Excessive use of agrochemicals in shallot soil can contaminate the environment and reduce the quality of agricultural products because it is suspected that fertilizers and some pesticides contain heavy metals. The study purpose: 1) determine Pb and Cd content in fertilizers and pesticides used by shallot farmers in Wanasari, Brebes Regency, 2) decide the agrochemicals effect on Pb and Cd concentrations in soil and shallot, then provide environmentally friendly technology with biochar, compost, and botanical pesticides. The study was conducted in Wanasari, Brebes Regency, Central Java from March until October 2020. These studies include a sampling of fertilizers and pesticides that are widely used by shallot farmers in Wanasari Brebes and plot research in the field. The technological approaches used in this study are using biochar, compost, and botanical pesticides. Shallot seed used was the Bima Brebes variety. Analyzes of total Pb and Cd content in the soils and plants were determined using the HNO3:HClO4 extract and measured with an atomic absorption spectrometer (AAS). In this study, analysis was carried out on 11 pesticides with Pb and Cd content of 2.70-22.31 mg/kg and 0.04-0.50 mg/kg, respectively. The Pb and Cd contents in six fertilizers were 10.53-28.09 mg/kg and 0/07-0.52 mg/kg, respectively. Total Pb and Cd in soil are still below the critical limit of heavy metal required for agricultural soil. Heavy metal concentrations of Pb and Cd accumulated in the root > leaf > bulb for all treatments. The use of botanical pesticides, biochar, and compost needs to be developed at the shallot farmer level in several growing seasons so that it is expected to increase crop yields, reduce the cost of chemical pesticides, and be environmentally friendly.