Preliminary investigations on the penetration and persistence of DDT under pasture

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.