Effect Of Eutrophic Sewage Irrigation On Soil Physical Properties

Irrigating using municipal sewage is not only an approach of effective using and protecting water resources, but also a way of treating urban sewage. This technology is widely used at home and abroad, however, there are few researches about the effect of sewage irrigation on soil physical characteristics at present. In this paper, the soil physical parameters, mechanical properties and hydrodynamic performance were studied by laboratory test of eutrophic sewage irrigation in loamy soil and sandy soil in Shihezi. We reached the following conclusions:(1) Two kinds of soil organic matter content increased with eutrophic sewage irrigation. After 50 times irrigation, organic matter content in sand soil increases from 0.85g/kg to 1.16g/kg, Its growth rate is 36.5%; While organic matter content in loamy soil changes from 2.73g/kg to 5.38 g/kg, and its increase amplitude is 97.1%.(2) The bulk density of two kinds of soil increased with the times of sewage irrigation. The increment in loamy soil is larger than that in sand soil. In the course of sewage irrigation, soil porosity increases first with exponential law, then comes to stable state. After 15 times sewage irrigation, the porosity of sandy soil increased 3.7%, and stabilized at this level. The porosity of loamy soil become stabile after 25 times sewage irrigation and increased 4.0%. Compared with the sandy soil, the stability time of loamy soil porosity is longer, but the increment in the porosity of the two almost equal.(3) The water-holding capacity of two kinds of soil increased after eutrophic sewage irrigation, but the effect of irrigation on the loamy soil is greater than sandy soil. Their field water-holding capacity increases with "S" curve. After sewage irrigation, soil-holding capacity of sandy soil increased from 26% to 28.5%, then reached stable. The percentage growth rate is 7.7. The water-holding capacity of sandy soil is 1.9 percentage greater than clear water irrigation. Soil-holding capacity of sandy soil increased from 27.5% to 31.6%, then got stable. The growth rate is 15 percentage. There is 4.1 percentage greater than clear water irrigation on loamy soil.(4) The liquid and plastic limit of two kinds of soil increased under eutrophic sewage irrigation, but the plasticity index was basically invariant, which means that the range of soil moisture content for suitable farming increases and stage of cultivation growths. The shear strength of loamy soil was also strengthened, while it did not change in sandy soil.(5) Soil matric potential suction increased after sewage irrigating, When infiltrating using cleaning water and sewage in the loamy soil, the soil saturated water conductivity Ks were 0.0019cm/min,0.0024cm/min, respectively; When infiltrating in the sandy soil, the soil saturated water conductivity Ks were 0.0049cm/min,0.0104cm/min, respectively. The former is almost 10 times less than the latter.