保水剂对土壤持水特性的作用机理研究

摘要

In order to explore the function and mechanism by using the super absorbent polymer to improve soil wa-ter-holding characteristic , put three types of super absorbent polymers with different dosages (0 .05% , 0 .10% and 0 .50% ) into sand soil without aggregate pore ,to measure the soil moisture content of each treatment under different suc-tions ,successfully fitted soil water characteristic curve by V-G model ,and acquired the results of the soil water charac-teristic curve parameter and main water constants for each treatment .The results indicate that:(1 ) After using the super absorbent polymer ,except the soil unavailable water had no significant change ,the saturated soil water content ,field ca-pacity ,gravity water and available soil water in all treatments had significantly increased .When we used 0 .50% super absorbent polymer ,the field capacity in this treatment was 3~4 .7 times higher than the control group .Using the super absorbent polymer ,the water-holding capacity in middle and low water suction segment was significantly improved ,that was the soil pore for holding water .(2 ) The soil water characteristic curve for each treatment was moved to the right ,the water-holding capacity in each suction section was increased .The n value was total less than the control group ,which in-dicated that super absorbent polymer can significantly improve the soil water-holding capacity in the dehydration process . (3 ) After using the super absorbent polymer ,the soil added absorbent water mainly derived from gravity water and avail-able water .When we use 0 .05% of the super absorbent polymer ,the proportion of the gravity water in each treatment was high than 60% .With the dosages increasing ,the proportion of the gravity water was decreased and the available wa-ter was increased .It indicated that mechanism of super absorbent polymer to the soil water-holding characteristic was mainly embodied the increase of the proportion of water held by capillary pore .When use low dosage ,the soil gravity wa-ter can be significantly improved ,but with the increase of the dosage ,the soil available water was significantly improved . (4 ) Comprehensively compared the improving effect of the super absorbent polymer type ,the B3 with 0 .50% dosage was the best improvement effect .From this ,even though the super absorbent polymer was a kind of substrate with strong abil-ity of moisture-absorbing by molecule ,it can be greatly changed the water-holding capacity by soil pore and increase available soil water capacity .So it should be given great attention and widely used .%分别将B1（北京华瑞祥科技有限公司高吸水树脂保水剂）、B2（广东东莞市安信保水有限公司农林保水剂）、B3（唐山博亚科技工业开发有限责任公司的高能抗旱保水剂）3种保水剂以不同用量（0．05％、0．10％和0．50％）施入无团聚体孔隙的风沙土中，测定各处理土壤在不同吸力时的含水量，并用V－G模型拟合各土壤水分特性曲线，获得各处理土壤的水分特性曲线参数和主要水分常数等结果，以期揭示使用保水剂在改善土壤持水性方面的作用特征和机理。结果表明：①使用保水剂后，除土壤无效水部分无显著变化外，各处理土壤饱和含水量、田间持水量、重力水和有效水部分均显著增加，保水剂用量为0．50％时处理土壤的田间持水量比对照高3～4．7倍，使用保水剂显著改善了土壤中、低水吸力段的持水容量，即土壤的“孔隙”持水部分。②各处理土壤的水分特征曲线右移，各吸力段的持水容量明显增加，n值均小于对照，表明使用保水剂显著增大了在失水过程中土壤的持水能力。③使用保水剂后，各处理土壤增加的吸水量主要来源于重力水和有效水，保水剂用量为0．05％时，各处理土壤重力水所占比重高于60％，随着保水剂用量增加，重力水所占比重下降，有效水分所占比重提高，表明保水剂对土壤持水特性的作用机理主要体现为增加了土壤的“毛管孔隙”持水比例，即在低使用量时显著改善土壤重力水部分，随着保水剂使用量的增加则显著增加土壤有效水部分。④综合比较保水剂类型和对土壤持水能力的改善作用，B3型保水剂在使用量为0．5％时的改善效果最好。由此得出，化学保水剂尽管是一种具有很强分子吸水能力的基质，却在土壤中能够极大地改变土壤“孔隙”持水性，增加土壤有效水贮量，应当受到应有的重视和广泛使用。