Based on meteorologic data the temperature regime of purple soil in
Sichuan Basin was estimated for the application of soil
taxonomic classification. Mean annual values being taken as variables,168 series of data were collected from 14
meteorologic observation stations.6 major factors were chosen out of 10 meteorologic ones by means of the successive regression method. In the light of the fact that the thickness of soil layer is thin in most of the region,the caiculation equations of soil temperature for different controlicd temperaturc soil layers Within 50cm depth beneath soil surface were established. For the soils of≥30cm in thickness,their temperature can be calculated in accordance with mean annual air temperature, relative humidity , evaporationeapacity and total cloud Cover;whereas,for those of <30cm in thickness,the same can be doneonly with the latitude, mean annual air temperature and wind velocity. Compared with other methods of soil temperature estimate, the present method ischaracterized by the following:1.Temperature regune for different soil layers was estimated , which was of signifieance to hilly regions with thin soil layer.2. It provided a reference for someplaces in which the monthly change of soil temperature needs to be known,for the predictionequations can be not only used to calculate mean annual soil temperature, but alse to calculatemean monthly soil temperature. 3.So far as the application of
soil taxonomic classification isconcerned,the prediction equations were of high precision , while they contained fewer factors.It was concluded that the present region belonged to the thermic soil temperature regime(15 22℃)from the results of soil temperature in different parts of Sichuan Basin.