中文摘要：

为了明确冻融作用是否有助于解决免耕或少耕带来的土壤容重增大等问题，我们在黑龙江省嫩江县鹤山农场进行不同含水量、不同容重的黑土冻融试验。结果表明：不同含水量的土壤（容重1．30g cm^-3）在冻融作用后20cm内土壤容重基本减小．但减小幅度与含水量之间不是完全的正比关系。不同深度土壤容重的变化规律是：高含水量时，表层容重减小幅度较大，下层减幅相对较小；低含水量时，则相反。冻融作用对不同容重土壤（含水量30％）的表层容重影响较大，它使小容重土壤变得更加致密；使大容重土壤变得疏松。黑土区冻融作用对免耕带来的容重增大问题可以起到一定的减缓作用。

英文摘要：

In order to make sure whether freezing and thawing due to no tillage or reduced tillage, a freezing and thawing could help to solve the bulk density increased problem experiment was done in Heshan farm of Heilongjiang Province. The water content treatments were 10%, 25.93%, 30.86%,and 37.84% respectively, and soil bulk density treatments were 1.01, 1.17 and 1.32g cm-3 respectively. The soil studied was silty loam and sieved by 2 mm in advance, then put into a barrel after harvesting and before the winter. Depth of the soil was 25cm. Before planting, soil bulk density was measured at the internal of 5cm in 20cm depth. The results showed that bulk density in 20cm depth was less after freezing and thawing of the soil with different water contents and with the same soil bulk density of 1.30g cm-3. But decreasing range was not absolutely direct proportion with water content. Variation of soil bulk density with the depth was： when soil water content was high, decreasing range of soil bulk density on the surface was more than the lower; when it was low, the variation was reverse. Freezing and thawing inflected much soil bulk density on the surface of the soil with different bulk density and with the same water content of 30%. It made soil with low bulk density compacted and high loosened. Generally, it was freezing soil bulk density increased by no tillage or reduced tillage in the and thawing that could overcome the disadvantage of black soil in a certain extent.