Study On Soil Moisture Transfer And Migration Of Nutrient Substance In Water Conservation Forest Of Miyun Reservoir In Beijing,China

Miyun reservoir is the source of life in Beijing. The water conservation forest has important role in forest. Soil physical structure has very important influence to surface runoff, soil moisture transfer, the growth of forest vegetation and so on. In addition, the movement of moisture in the soil can affect soil structure and soil nutrients.In consequence, analyzing and discussing the change of the forest moisture transfer is of great significance to the sustainable development of reservoir area and the healthy growth of the forest ecological system. It also has an influence to the reasonable development and utilization of water and the protection of the ecological environment. This article selected three sites to take undisturbed soil column through an acrylic tube (diameter of 30cm and high 50cm) in the water conservation forest surrounding the Miyun reservoir. It uses constant head (5mm and 10mm) to take breakthrough experiment using TDR probe to analysis the influence of moisture transfer rate and the main nutrient substance (organic matter, nitrogen, phosphorus and potassium)in the soil. The results of the study are as follows:(1)The water conservation forest in Miyun reservoir has well-balanced soil structure, plot 1 and 2 have similar soil structure and soil nutrient substance content. Nutrient substance content in the soil is decreasing with soil layer deeper.(2) Under the same head pressure the second initial rate and stable rate increased, and steady infiltration time and starting infiltration time shortened. The maximum rate was not affected. In the process of test, soil electrical conductivity are less than 0.5 mS/cm and soil salinization probability is low. With the increase of the number of test, the soil hydraulic conductivity of the same soil layer is reduced.(3)The influence of soil structure on moisture transfer are:Gravel content had a strong correlation with initial rate (R2=0.919). Sand content and silt content had a strong correlation with stable rate respectively (R2=0.892; R2=0.798) and maximum rate respectively(R2=0.698; R2=0.666). Clay content had a little effect on the process of moisture transfer. Total porosity have little effect on the moisture transfer. Capillary porosity had a strong correlation with initial rate(R2=0.811). Non-capillary porosity and had strong correlation with stable rate (R2=0.748) and the maximum rate (R2=0.662). Soil density had strong correlation with steady infiltration time (R2=0.918) and the maximum rate(R2=0.633).(4)The moisture transfer had less effect on the soil organic matter and available phosphorus. The moisture transfer had a strong influence on the total nitrogen and available potassium. Moisture transfer could reduce the content of total nitrogen and available potassium in the soil.