Study On Cause Of Waterlogging Of Slope Fields Of Black Soil In North Region Of North-east China

The black soil region in Northeast is important food base of China and the fertility content of this soil is high, it plays a great role in food safety and national economy. However, the original ecological environment had been destroyed heavily. The problems of arable land degradation, such as soil and water loss, soil erosion by wind and soil water disequilibrium, attract attention of all walks of life.Slope gradient of black soil farmland was most 1° -5°, where disasters of water logging and waterlogged happen frequently in some small parts and the disasters can last more than 6 months. These spotted small wet areas in farmland were called 'wet-kang land' by people. This typical water logging land distributes in the slope farmland of black soil fragmentarily, which unit area was about 10~900a and the resistance of soil to drought and logging was weak. In order to improve land use rate and resolve the problem of land degradation caused by soil moisture imbalance, Hydrology Bureau of province Heilongjiang reclamation area arranged 'wet-kang land' treatment for a major science and technology project early in 1998, but due to lack of adequate causes of treatment, 'wet-kang land' management technology was not popularized widely. In addition, black soil ability of holding water was powerful, parent material was sticky, farmland soil saturate easily, so how to prevent water logging disasters has become the first issue of the study on soil and water conservation measures.Discussing soil water conversion and storage and researching the cause of water logging in black soil region by analyzing soil-geology, soil-hydrological can provide scientific basis for harnessing slope farmland. The study is also very important for research soil and water loss and soil and water conservation measures of slope farmland.This article studied preliminarily some factors of 'wet-kang land' mainly. The results showed that: the cause of slope farmland of black soil saturated was interacted by nature and artificial factors such as the formation of soil-geology, physiognomy and topography characteristic, climate hydrological, soil physics characteristic and so on. Rainfall, physiognomy and topography characteristic and the formation of soil-geology were dominant factors, others were derivative factors which accelerate or lighten water logging of the slope farmland.1. The formation of soil-geology was: Black soil developed from clay parent material generally, which thickness was 10- 40m.There were some fragmentary sandy layers in clay parent material. Clay saturated hydraulic conductivity was about 0.01mm/min under boundary layer 1m.2. The atmospheric water was the only source of black soil region. Because of the higher holding hydropower of black soil and slower water permeability, rainfall infiltration depth was no more than 2m usually; and soil moisture was affected obviously by atmospheric water and evaporation from surface to lm. The depth and thickness of sandy layer in clay parent material...