THE EFFECT OF PESTICIDES APPLICATION ON PHENOLIC ACID CHANGES AND CO2 AND CH4 PRODUCTIONS FROM PEAT SOIL

摘要

Peat soil contains organic matters, in which their degradation produces phenolic acids, CO2 and CH4 Phenolic acids are known to be toxic to plants. This study was aimed at evaluatingeffects of two pesticides: herbicide paraquat dichloride and insecticide BPMC, on phenolic acids of peat soil. Pesticides that fall into peat soil will react with organic matters and its degradation products. Soil samples were taken from paddy field peat soil at Kanamit Jaya Village, District of Maliku, Pulang Pisau, Central Kalimantan. The pesticide dosages usedwere based on the recommended application dose, i.e. 4 liter ha-1 for paraquat and 1 liter ha~(-1) for BPMC. Treatments consisted of 3 levels of dosage (half, equal and twice): 1104 ug kg~(-1), 2208 ug kg~(-1), 4416 ug kg~(-1) for paraquat and 485 ug kg~(-1), 970 ug kg~(-1), 1940 ug kg~(-1) for BPMC with single control. After 1, 7, 14 and 28 days of incubation, soil in each treatment was analyzed for phenolic acids, pesticide residues, function groups, and CO2 and CH4 productions.Results showed that pesticide applications reduced total phenolic acids in peat soil. Paraquate and BPMC applications showed similar pattern. BPMC at the rate of 242.5 ug/500 g soil showed 95% residues reduction, higher than other dosages. Meanwhile, all dosages of paraquat provided 100% reduction of residues. Analysis using FTIR did not detect any additional functional groups. However, altered intensity of absorption peaks could be an indication of compositional changes of chemical substances within peat soil during incubation period. Pesticides application did not increase CO2and CH4 emissions.