Water retention capacity of soil for high absorbing water resin of PAAM

The effect of different mass of poly(acrylic acid-acrylamide) superabsorbent (PAAM) on water retention capacity of soil in tap water and 0.9%NaCl aqueous solution was investigated at different ratios of river sand/soil. The results have shown that the times of decreasing the water retention ratios by 30% relative to the comparative experiments (no PAAM) in tape water have prolonged for another 560 h, 445 h, 360 h and 350 h for four different ratios of the river sand and soil: 10:0, 5:5, 3:7 and 0:10, when the using mass of PAAM is 5 g per kg soil under the natural evaporation conditions. The equilibrium absorbencies of soil in tap water are increased by 4.5, 2.6, 2.2, 1.6 and 1.2 multiple for five different ratios of the river sand and soil: 10:0, 7:3, 5:5, 3:7 and 0:10. When the critical using mass of the PAAM is 5 g per kg soil, the granular structure of the soil can be improved obviously and the applying require can be satisfied. However, the absorbency of PAAM in 0.9% NaCl solution is greatly reduced and the increasing water retention capacities are small when PAAM is used in the areas of saline-alkali soil. And the PAAM is suit for use in the areas of the sandy soil while it is not suit for use in the areas of high saline-alkali soil.