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 (Costelytra). 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 between rates of application ranging from 1 to 8 lb pp'-DDT per acre.