Preliminary investigations on the penetration and persistence of DDT under pasture

Abstract

DDT is applied to pasture in conjunction with superphosphate, for the control of damage by soil insects, particularly grass-grub (C ostelylra). In a plot trial on Papatoetoe silt loam, DDT penetrated to a maximum depth three months after application. Most of the insecticide recovered was associated with the top 2 in. of soil. Decomposition of DDT appeared to take place solely within the top 1 in. of soil, approximately 50% loss being observed in the initial 12-month period of the trial. No significant difference in distribution pattern or breakdown rate could be detected hetween rates of application ranging from 1 to 8 lb pp'-DDT per acre.

DDT residues in the environment—A review with a New Zealand perspective

“…Rapid initial loss of DDT has also been observed in a field trial at Otara, New Zealand (Gallaher & Evans 1961). Rate constants for DDT loss were found to decrease during the first 3 months after application and were then similar until measurement ceased at 12 months.…”

Use of organochlorine contaminants to measure sedimentation rates in estuaries: a case study from the Manukau Harbour

“…Discussions with residents who have farmed in the area for 30 or more years, and with agricultural contractors, manufacturers and researchers familiar with the region, have enabled us to make some rough estimates of DDT use. Between 1950 and1970, DDT was applied to about 5000 ha of dairy farms at a rate of about 2 kg hal every 3 years (Gallaher and Evans, 1961). Thus, up to 70,000 kg of DDT may have been applied to the catchment.…”