The Impat Of Poly(Acrylamide) On Soil Physical Properties And Photosynthetic Characteristics Of Plants

Mining subsidence led to the deterioration of soil physical properties, soil moisture changes caused by deterioration of physical properties is the most important factor limited the ecological restoration of mining subsidence area. There were a lot of subsidence cracks, resulting in more intense evaporation and posing a huge threat to the growth and survival of vegetation in Shen dong mining subsidence area of semiarid area. In this paper, the effects of five different contents(100mg/kg、200mg/kg、400mg/kg、 600mg/kg、800mg/kg) by mixing PAM solution with soil and sprinkling PAM powder on soil surface on soil physical properties and alfalfa (Medicago sativa Linn.) photosynthetic characteristics were researched. Soil physical property indicators and photosynthetic characteristic indicators were measured, analyzed and evaluated comprehensively to get a basic regulation of the impacts of PAM, and to provide a basis for the filed researches and the promotion of PAM in coal mining subsidence area. The main conclusions are as follows:(1) PAM could effectively inhibit soil evaporation of mining subsidence. The most optimum concentration of mixing and sprinkling method were 600mg/kg and 400mg/kg. The soil evaporation of various treatments was available to the logistic regression model and the models fit better.(2) PAM could significantly increase filed capacity, capillary water capacity and soil aggregates, and reduce soil bulk density. In the mixing method, the most suitable PAM amount for filed capacity, capillary water capacity, soil aggregates and soil bulk density were 400mg/kg,600mg/kg,800mg/kg, and 800mg/kg. In the sprinkling method, the most suitable amount for filed capacity, capillary water capacity, soil aggregates and soil bulk density were 600mg/kg,400mg/kg,800mg/kg, and 800mg/kg.(3) PAM could improve the plant net photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency and reduce intercellular CO2 concentration. There were significant differences (P<0.01) for plant photosynthetic characteristics between the two methods. In the mixing method, the most suitable PAM amount for net photosynthetic rate, stomatal conductance, low intercellular CO2 concentration, transpiration rate and water use efficiency were 600mg/kg,600mg/kg,600mg/kg,800 mg/kg, and 800mg/kg. In the sprinkling method, the most suitable amount were 600mg/kg,600mg/kg,400mg/kg,800 mg/kg,800mg/kg.(4) For a comprehensive evaluation of the indicators above, the results showed that: soil physical properties could be improved and the growth of plants could be promoted by applying soil amendment PAM. The proposed concentration was 400-600mg/kg during vegetation restoration and reconstruction in coal mining subsidence area.