Effect of crop residue cover on soil temperature in cold and dry farming areas

For testing the effect of crop residue cover on soil temperature at various percentages of covered areas, the test plot was established in west rainless region of Heilongjiang Province. And, the soil temperatures of each layer underground 5, 10, 15, 20 cm were measured respectively by using WQG-16.-21-61℃ a knee bend ground thermometer. The testing results indicate there is a visible regulating effect in soil temperature with crop residue cover. Compared with uncovered soil, the soil temperatures of each layer were increased by 1.5～2.1℃, 0.9～1.2℃, 0.2～0.9℃, 0.4～0.8℃ respectively. The regulating effects in soil temperature were reduced with the increase of the depth of soil layer. From April 20^th to June 15^th, the soil temperature increased with the increase of covered amount, and decreased instead when the covered crop residue over a certain amount. After June 20^th, the soil temperature decreased with the increase of covered amount, among which, the soil temperature decreased by 1.1～1.5℃, 2～3.6℃ when the covered amount 30%, 50%～80%. The decreased range is maximum on soil surface, and less and less in the direction of depth. As a result, covering with crop residue to increase the soil temperature is advisable and feasible in northern cold farming areas, in consideration of soil temperature.