Study On Effects Of Superabsorbent Polymers On Physical Properties Of Loessial Soil, Cinnamon Soil And Sandy Soil

Basic properties of Superabsorbent Polymers, effects on soil function after SAP mixed with soil, and long-term quality of SAP using were not revealed so comprehensively and exactly in the agriculture and forestry domain, especially soil moisture-energy relationship and soil capacity of keeping water and fertilizer.This research was focused on these points. Three typical significance soil and several common SAP on domestic and international market were selected for testing.Accurate determination indoor-test and long-term field-test were combined to test impacts of soil under the role of SAP. Searching the role of laws of SAP affecting on soil benefits for variety selection, concentration formulation, and evaluation.This research were divided into two parts, indoor-test and field-test. Indoor-test was also divided into two parts.First part were conventional properties and impact factors testing.The second part were variety selection and effect on SAP under low temperatures. The field-test, second part, were effect of loess soil, cinnamon soil and sandy soil under action of SAP, which Including actions on energy state of soil moisture, main physical properties, soil capacity of keeping water and fertilizer. Action mechanism of SAP in soil was revealed through comparing analysis of the index of releasing-water performance, soil-moisture characteristics, soil bulk density, porosity, granular structure,and capacity of keeping fertilizer of N, P,K. Appropriate SAP were chosen for different soil after appraisal and analysis.The field-test were divided into three parts, that is, applications of SAP in afforestation in loess soil, cinnamon soil and sandy soil Regions.Mechanism of SAP acting on plants were revealed through analyzing of effect on growing and physiological indicators,which including Height, DBH (Diameter), Capacity of Photosynthesis and so on.. Conclusion were drawn from above analysis:(1) Water absorbency of SAP was affected by PH value and ion concentration of solution. The more acidic (or alkaline),the smaller amount of the water absorbency.The higher metal ions concentration of solution,the lower water absorbency SAP had.High valence metal ions had a intensiver inhibition action than that low ones.A preliminary study was made to text whether the low temperature of northern China in winter influenced properties of Superabsorbent Polymers or not.The results shows that water absorbency of SAP obviously decreased when temperature reduced to -20℃according to Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B).Water absorbency of Polyacrylate with Macromolecule (Type C) decreased when temperature reduced to -15℃.(2) Superabsorbent Polymers obviously improved soil moisture and available moisture content for plants,but which were not similar to a linear related. The degree of improvement performanced on enormous diversity during to different soil water suction. The ameliorating effect in low soil water suctions (<0.8 MPa) significantly superior to the high soil water suctions (0.8～1.5 MPa), especially less than 0.05 MPa. It is that soil moisture and available moisture content strengthened obviously when the SAP concentration raiseed. The increasing trend basically consistented with the diminishing law of exponential relation.(3) Superabsorbent Polymers effectively improved soil three-phase proportion,increased total porosity and capillary porosity, reduced soil bulk density, and promoted the formation of soil granular structure.Superabsorbent Polymers obviously promoted granular structure of soil between 2-0.25mm and it does little mater to SAP concentration according to loess soil. For cinnamon soil, Superabsorbent Polymers mainly promoted soil granular structure between 1-0.25mm under lower SAP concentration,and fiercely promoted soil granular structure between 2-0.5mm under higher SAP concentration.(4) Superabsorbent Polymers enhanced soil adsorption of fertilizer,and reducing fertilizer leaching quantity,which conducive to assimilating of plant nutrients.According to ability of keeping potash fertilizer, Copolymer of Polyacrylamide and Potassium Acrylate (Type A)>Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B)> Polyacrylate with Macromolecule (Type E). For ability of keeping nitrogenous fertilizer, Copolymer of Polyacrylamide and Potassium Acrylate (Type A)> Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B)>Polyacrylate with Macromolecule (Type E) according to partial cohesive soil,and whicn in Partial Silt soil was the opposite. The ability of keeping phosphate fertilizer differed not quite amony the three soil.(5) Applicability of SAP in soil was that:According to loess soil,Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B)>Polyacrylate with Macromolecule (Type E)>Polyacrylate with Macromolecule (Type C)>Copolymer of Polyacrylamide and Potassium Acrylate (Type A)> Polyacrylate with Macromolecule (Type D). According to cinnamon soil, Copolymer of Polyacrylamide and Potassium Acrylate (Type A)>Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B)> Polyacrylate with Macromolecule (Type E)> Polyacrylate with Macromolecule (Type C)> Polyacrylate with Macromolecule (Type D). According to sandy soil,Copolymer of Polyacrylamide and Potassium Acrylate (Type A)>Copolymer of K-Polyacrylic Ester-Polyacrylamide (Type B)> Polyacrylate with Macromolecule (Type C)> Polyacrylate with Macromolecule (Type E)> Polyacrylate with Macromolecule (Type D).(6) Field tests showed that:SAP processing obviously promoted main growth indices and efficiency of photosynthesis, which accumulating biomass of plants.But reasonable usage mode and amount were the Prerequisites.