Factors that influence the persistence of TCA in soil

The persistence of TCA in soil was examined using the pyridine-alkali colorimetric procedure. Loss of TCA was essenlially similar when determined by colorimetry, chloride release or bioassay. Persistence of TCA when incubated with soil at 25°C or sprayed on the soil surface in the field was slightly influenced by soil type. Degradation of TCA occurs largely by microbial action after a lag phase. Soils treated with TCA acquire the ability to degrade further additions of ihe compound without a lag phase. The three soils examined still possessed this ability to differing extents 32 months after they had been sprayed once with TCA at the rate of 22.4 kg/ha. In one experiment the persistence of TCA was shortened appreciably in a plot that had twice previously been sprayed with TCA.