Show DDT Residual Effect i In Soil is Proved Recent research by the US U.S. Department De De- of Agriculture shows that thata a single application of DDT to the soil soU will kill some species of bugs and ind grubs for at least a year five period Tests conducted in several everal locations locations loca loca- in the northeastern states show an average DDT carryover in turf of 92 per cent after two years e r. r of 43 per cent after four tour years year 38 98 per cent after six years and 29 per cent after seven even years' years time Dug D Bug g experts also found that the rate rate of application had little influence influence in In- fluence on the percent of ot toxic residue in the soil soU Soil SOU samples treated at the rate of 25 to 50 ro l pounds of ot DDT per acre show how the percentage carryover r after eight years year of testing was about the same In either case cue The difference was minimum Tests Teats with different soil types prove that DDT lasts last longer in poor soils JOU a shorter time in soils soil high in organic matter Results X of ot experiments with samples of ot 83 M different soil IOU types type from seven even states showed that persistence of ot DDT was about the same ame In sand sandy slit silt or cla clay loams loam but much I greater in soils heavy beaV In sand land con cone tent After uter analyzing Japanese I beetle grubs it was found that DDT began losing its Us killing power only Jn to the fifth year after I tion A single DDT PDT treatment at 25 pounds per acre produced ed a 98 per percent percent cent grub kill within tour four weeks after the grubs were put in the soil during the first four tour years tIt t It required sl slightly more than five weeks week for tor the same lame kill kW the fifth year J 4 |