Experimental Study Of Modified Materials Effect On Soil Infiltration And Water Feature

Urban green space as the only negative feedback regulation system which performs "absorbing pollution and releasing new organisms"in nature, it plays an important role in improving urban ecological environment and beautifying the city landscape. While as the base plate of urban green space, urban green land is subjected to the influence of environmental pressure from urbanization and human activity, the physical and chemical properties are greatly changed, and the soil quality is decreased obviously. These changes will directly affect normal growth of the trees,flowers and plants, lead to some ecological environment problem, such as soil erosion,water resource depletion.sand disasters and so on, then affect the quality of green space and urban greening effect. More importantly, the degeneration of soil physical property is becoming more and more popular, for instance, poorer soil,less soil porosity,lower content of effective water, waterlogging of rainy season,drying of dry season. Therefore, it is urgent to improve the urban soil physical properties.At present, the improvement of urban green land is mainly adding different structure-improving agents into soil, as far as the organic modified materials are concerned, they not only can improve soil physical and chemical properties, but also can increase soil nutrients. So the laboratory experiments were conducted to study the effect of the modified materials used singly or in combination on soil water infiltration and characteristics in the paper. The modified materials include greenery plant waste,sand,desulfurization gypsum and PAM.The results were showed as following:(1)The cumulative infiltration well,moist peak displacement and soil moisture characteristic curve were fitted the Kostiakov infiltration model (1=Kt1-α),the power function (F=atb) and Van Genuchten equations, and the decision coefficient(R2) are above 0.99. (2)The soil infiltration were increased and the moist peak down were promoted by adding the sand into soil, but the soil water-holding capacity and effective moisture are significantly reduced, and water storage capacity were weakened. With the increase of the sand content of sand, soil infiltration ability increased, and moist peak shifted down quickly, however water-holding capacity and the effective water content decreased. Then sand particle size have a certain effect on soil water infiltration, but it have no obvious impact on soil effective water, and water infiltration performance abated and moist peak went forward slowly with the decrease of the sand particle size. (3) Greenery plant waste not only can improve the soil infiltration and moist peak declining in depth, but also can improve the soil water-holding performance and the effective water content. The soil water infiltration was not influenced significantly by greenery plant wastes used singly, but the soil water-holding properties and the effective water content were improved significantly. (4)It was obvious that the desulfurization gypsum improved soil structure, enhanced soil infiltration and increased the effective water content. (5)Although PAM suppressed the soil water infiltration, it can weakened the attenuation speed of water infiltration capacity. Moreover PAM increased soil water content due to its strong water absorption ability, and decreased soil effective water content because of weaken water releasing.In a word, the soil improved ventilation pervious ability by adding sand to the clay soils, but the water retention were poor. Combined use of the greenery plant waste,desulfurization gypsum and PAM, which should be applied in the modification of urban green land, it not only can speed up the moisture infiltration, reduce the attenuation rate of infiltration, maintain soil water infiltration capacity, and at the same time effectively improve soil water-holding ability, better accumulate effective moisture in the soil, so it is worthy of applying in city greening soil improvement.