Influence of several soil properties on the degradation of EPTC in some New Zealand soils

Open Access
Publisher Website
Google Scholar
Abstract
At several sites in 2 areas of the North Island, New Zealand, soil samples were taken from maize and sweet corn fields treated with the herbicide EPTC for several years and from nearby untreated paddocks. The soils were tested (using gas liquid chromatography equipment) for EPTC degradation rates, and analysed for organic carbon, specific surface area, pH, total nitrogen, clay percentage, and clay type. Times for 1/2 and 3/4 of the added herbicide to degrade were estimated. The mean EPTC degradation rate over 28 days was found to be of minimal use, because it can mask the dramatic changes occurring in this period. Differences between treated and untreated soils were about 4.3 days at 20°C and 20% moisture. Faster EPTC degradation was correlated with increased levels of organic carbon, but sandy soils low in organic carbon also degraded the herbicide rapidly because of low adsorption. Generally, faster EPTC degradation occurred in soils of low pH and high carbon/nitrogen ratio — conditions which suit the fungal activity believed to be responsible. The balance between adsorption and biomass is important in predicting EPTC degradation rates.