聚丙烯酸钠的释水特征及对土壤物理参数的影响

摘要

聚丙烯酸钠作为保水剂的一种,在农业应用中能够防止水土流失,改善土壤水分状况,促进作物增产,提高作物品质.通过室内试验分析了聚丙烯酸钠的释水特征及土壤中混施不同比例(0、0.3％、0.5％、1％和1.5％)聚丙烯酸钠对土壤饱和导水率、收缩比和紧实度的影响.研究结果表明,聚丙烯酸钠释水与混施土壤后释水存在较大差异,100％聚丙烯酸钠在1.5 MPa吸力条件下能保持46.4％的水分,而在干土中可以快速100％的释放水分;随着土壤聚丙烯酸钠用量的增加,土壤透水性急剧降低,均匀混施达到1％时,饱和导水率接近0 m·d-1;干燥后土壤紧实度和收缩比增加,导致聚丙烯酸钠的农业应用也存在一定的潜在风险.%Application of sodium polyacrylate (PAANa) in agriculture can prevent soil erosion,increase soil moisture,increase grain yield,and improve crop quality.Through laboratory experiments,the water release characters of PAANa was analyzed,and the saturated hydraulic conductivity,shrinkage ratio and compactness of soil under different application ratio of PAANa (0,0.3％,0.5％,1％ and 1.5％) were measured.The results showed there was a great difference in water release between PAANa and mixed application with soil.PAANa could absorb 46.4％ water at the suction of 1.5 MPa,but could release 100％ water in dry soil.The soil water permeability dramatically decreased with the increase of PAANa ratio,and the saturated hydraulic conductivity decreased nearly to 0 m day-1 when the ratio reached 1％.Soil compacmess and soil shrinkage ratio increased after drying,thus there were some potential risks when applying PAANa in agriculture.