Changes of Physical and Chemical Characteristics along Soil Profile under Long-term Sprinkling Irrigation

Abstract：Based on the analysis of physical and chemical properties of soil samples along soil profiles from different types of irrigation area,the physical and chemical properties along soil profiles with two meters in depth in sprinkling irrigation area, underground water irrigation area, river water irrigation area and non- irrigation area were compared,and the varied characteristics along the soil profiles under long-term irrigation were revealed. The results show that compared with other irrigation zones, the moisture content along the soil profiles under long-term irrigation, especially for the heart and bottom layers of soils, had a more significant reduction; the soil dry bulk within the low pan and a certain depth below it had increased greatly; the organic matter content of the heart and bottom layers of soils under the long-term sprinkler irrigation has reduced very significantly. These changes of soil physical and chemical characteristics along the soil profiles are related directly with small scale irrigation. Because the water content along the whole profiles was at a low level within a long time, these conditions for soil dehydration, contraction and consolidation are met, which led to the increase of dry density and the decrease hydraulic conductivity within the plow pan and its adjacent soil layers, also, the decreasing of the total water flux through the soil profile under sprinkler irrigation blocks the migration of the deep organic matter and other substances into the deep soil layers.