The concentration of heavy metals in the potato tubers of the basic seed groups examined by the variation of fertilizers, pesticides and the period of cultivation

Abstract

The compost, insecticides, and fungicides used by potato farmers in Bali contain heavy metals Fe, Pb, Cd, and Cr. The purpose of this study was to analyze the impact of the seed group potato cultivation system on the concentration of several heavy metals in potato tubers. Cultivation was carried out in the rainy and dry season with: (1) NPK fertilization, (2) NPK fertilization, insecticide and fungicide spraying, (3) NPK fertilization and compost, and (4) NPK fertilization, compost, insecticide and fungicide spray. Each experimental unit was carried out by 5 farmers as a replication. The variables observed were concentrations of Fe, Pb, Cd, and Cr in the soil, plant parts, and potato tubers. Soil, plant, and potato tuber samples were taken randomly with 5 repetitions from the experimental unit. The Concentrations of Fe, Pb, Cd, and Cr metals in potato plants which are cultivated in the rainy season are on average greater in the amount of metal Fe = 1-21 ppm, Pb = 0.05-3.65 ppm, Cd = 0.01-0.15 ppm, and Cr = 0.02-0.18 ppm of concentrations in plants cultivated in the dry season. The metal content in the root zone of the potato seeds plants were Fe = 120.5 ± 3.2 ppm, Pb = 0.82 ± 0.17 ppm, Cd = 0.4 ± 0.1 ppm, and Cr = 0.59 ± 0, 2 ppm. Metal content in potato tubers were Fe = 0.1-0.3 ppm, Pb = 0.07-0.21 ppm, Cd = 0.03-0.06 ppm, and Cr = 0.03-0.07 ppm, these values are still below the food safety threshold according to WHO. The potato tuber which cultivated is still within safe limits for human consumption, but the spraying of insecticides and fungicides and the use of compost must begin to be limited because it causes an increase in Fe, Pb, Cd, and Cr metals in potato plants amounting 3.53-4.36 ppm, 0.41-0.5 ppm, 0.12-0.15 ppm, and 0.22-0.27 ppm, respectively. Fertilization using chicken manure compost at a dose of 10-20 tons ha-1 is very effective in supporting potato cultivation with the LEISA system. The ability of microbes in the compost to carry out an in-situ bioremediation process on Fe, Pb, Cd, and Cr metals is 49.61-55.60 ppm, 2.59-5.64 ppm, 35.24-52.44 ppm, and 19.68-54.24 ppm, respectively.