Indicators for the physical chemical and biological filtering capacity of pesticides in pasture and orchard soils

Abstract

Recently the loss of soil organic carbon (SOC) has been reported for some pastoral NZ soils The impact of decreased SOC on soil filtering capacity for pesticides was investigated using 24D The hypothesis was that in aggregated soils the filtering capacity for organic compounds depends on physical chemical and biological properties at the aggregate scale impacting water sorptivity pesticide sorption and pesticide degradation respectively and that these are related to the SOC content Indicators for these properties were identified namely the water repellency SOC content and microbial biomass and basal respiration rates Two pairs of sites with the same soil type texture landuse and climatic conditions but with significantly different SOC content within each of the pairs were selected For hydrophobic soils a SOC loss tended to have a negative impact on chemical and biological properties but a positive impact on the physical filtering capacity of aggregates for 24D