The Preliminary Study On Effect Of PAM On Physical And Hydraulic Properties Of Saline Soil In Hetao Irrigation District

In recent years, PAM is widely used in the soil erosion control, water saving irrigation, agriculture production, environmental protection as an ameliorant of soil structure.But now the research about PAM almost focus on non-saline-alkali soil, research on saline-alkali soil is little.The salt of saline-alkali soil play an important role in PAM and soil particle interaction.However, the effect of PAM on physical and hydraulic properties is not clear.According to this problem, this essay aim at Hetao Irrigation which has serious soil salinization problem and study the effect of PAM on physical and hydraulic properties of saline-alkali soil in laboratory tests with the view of ascertaining the changing rule of non-saline-alkali soil, slight saline-alkali soil, moderate saline-alkali soil with different dosage of PAM, and assessed the effect of PAM on the physical and hydraulic properties of slight saline-alkali soil.moderate saline-alkali soil. Finally,we draw somg conclusions as follow:1、PAM can obviously improve physical properties.of the non-saline-alkali soil and slight, moderate saline soil in the hetao irrigation area. PAM could increase the quantity of soil large aggregation. The quantity of soil large aggregation increased with the increasing of concentration of PAM. It can also decrease soil bulk density and increase soil porosity,soil capillary porosity. The comparison showed that the rule of the improvement in soil physical index is slight saline-alkali soil> non-saline-alkali soil>moderate saline-alkali soil.2、PAM can obviously reduce saturated hydraulic conductivity. The saturated hydraulic conductivity reduced with the increasing of concentration of PAM. The comparison showed that the rule of the reduction in saturated hydraulic conductivity is moderate saline-alkali soil>non-saline-alkali soil>slight saline-alkali soil; PAM can obviously improve soil water binding capacity. The comparison showed that the rule of the improvement in soil water binding capacity is slight saline-alkali soil>non-saline-alkali soil>moderate saline-alkali soil.3、PAM can obviously inhibit soil water evaporation. The comparison showed that the rule of the inhibition in soil water evaporation is slight saline-alkali soil>non-saline-alkali soil>moderate saline-alkali soil.4、PAM can obviously reduce infiltration rate, accumulative infiltration and wetting front, and infiltration rate, accumulative infiltration and wetting front reduced with the increasing of concentration of PAM.. The comparison showed that the reduction in soil water infiltration is moderate saline-alkali soil>non-saline-alkali soil> slight saline-alkali soil.5、The effect of PAM and soil particles is closely related with the existence of salt.Appropriate amout of salt can promote the adsorption of PAM and soil particles and enhance the effects of PAM.Because the cationic of electrolyte combine with anion of PAM and soil particles to be held and Promote the cementing soil grain to form soil aggregation. But too much salt may weaken the effect instead. Because lots of anion repel with molecular chain of PAM.It makes molecular chain of PAM curlied tightly so that the molecular chain does not have enough space to adsorption.Because PAM can improve soil physical properties.soil hydraulic properties must change.The effect of PAM on the saturated hydraulic conductivity、soil water binding capacity、soil water evaporation and soil water infiltration can indirectly response the conclusion that appropriate amout of salt can promote the adsorption of PAM and soil particles and enhance the effects of PAM, but too much salt may weaken the effect instead.