The rate of degradation of chloral in soils is in the following order:Quickest in salinized meadow soil,neat in paddy soil and slow in red soil.In general,when chloral exposed to the air and light,or in contact with an alkaline solution,it is liable to rupture at C-C bond and decompose into CHCl₃,Cl₂ etc.However,the transformation of chloral in soil proceeds chiefly to the formation of TCA instead of C-C bond rupture.The oxidation products have been identified by the derivative chromatography and by gas chromatography and mass-spectrography.The conversion rate of TCA from chloral was about 56%-76% with a persistent period of 70-100 days.