亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

Snow cover, as the most common upper boundary condition during freezing and thawing period in the cold region of northern China, directly affected the soil moisture distribution and movement, soil temperature and frozen depth, freezing rate, etc. In order to reveal the influence of snow on soil moisture movement, soil water and heat coupled transfer during freezing and thawing period was studied. Through field experiment, the soil moisture movement patterns of seasonal freezing-thawing black soil in Harbin were dynamically observed under the conditions of four different coverages: bare land, natural snow, compacted snow and thicken snow. The density and liquid water content of snow were measured by the Snow Fork, the liquid water content and total water content of soil were measured by time domain reflector and neutron moisture meter. From the perspectives of temporal and space change of soil moisture content, the results indicated that the thickness and density of snow can largely affect the protection of snow on soil, when only considering the subsidence of increased snow density, the greater the thickness of snow was, the better the protection was. The response of soil moisture content to temperature change and soil thawing time were delayed, the degree of delay was increased with soil depth increasing. Compared with increase of snow thickness, denser snow can protect the soil better, and the influence of temperature on soil was decreased. When winter snow was small, farmers can artificially compact it, which can strengthen the protection of soil.