Effects Of Regenerated Water Salinity On Soil Structure And Water Movement Characteristics

Since the rapid development of China's economy,water resources have become more important.The large increase in industrial and urban domestic water consumption has occupied the proportion of agricultural water use,which has seriously restricted agriculture and rural development,especially in the northwest and north China.Therefore,experts and scholars have thought of using reclaimed water for agricultural irrigation to alleviate the current shortage of agricultural water shortages.However,reclaimed water contains many inorganic suspended solids,salts,and organic matter.It is easy to cause the spread of pollutants and the migration of harmful substances into the soil.In this paper,the effects of salinity in the reclaimed water on the structural properties of the soil and the movement of the water were studied by indoor irrigation infiltration test.The effects of salt concentration,irrigation frequency and salt-irrigated water-clear water alternate irrigation mode on the agglomerate structure,bulk density,porosity,infiltration performance and maximum infiltration depth of reclaimed water were studied.The variation of soil water flow characteristics under different infiltration conditions.The results show:(1)The soil bulk density at the same depth decreased first and then increased with the increase of salinity in reclaimed water.The porosity and soil normalized average weight diameter increased first and then decreased with the increase of salinity in reclaimed water.In the test where the salt concentration reached 3.0 g/L,the soil bulk density at the same depth was the smallest,and the porosity and standardized average weight diameter were the largest.In the depth range of 0-10 cm,the total porosity and non-capillary porosity increase first and then decrease with the increase of salinity in the reclaimed water.The capillary porosity decreases first and then increases with the increase of salinity in the reclaimed water.The trend,the calculated ratio of non-capillary porosity to capillary porosity(non-capillary porosity/capillary porosity),shows a significant increase with decreasing salinity in the reclaimed water.Under the same irrigation times,the irrigation infiltration time,the side preferential flow and the bending coefficient of the preferential flow in the soil column(which is the non-uniformity of the flow)decreased first and then increased with the increase of the salt concentration in the irrigation water.(2)The soil normalized mean weight diameter and total porosity at the same depth decreased with the increase of reclaimed water irrigation frequency,and the soil bulk density increased with the increase of irrigation frequency.In the depth range of 0-10 cm,the irrigation frequency is the ratio of total porosity,capillary porosity,non-capillary porosity,non-capillary porosity to capillary porosity in 2 days and 4 days(non-capillary porosity)The rate/capillary porosity value is significantly higher than the same index value of the irrigation frequency for one test per day.The cumulative infiltration time,lateral preferential flow structure and the preferential flow structure of the soil column under the same irrigation water volume(which is the non-uniformity of the flow)increase with the increase of the irrigation frequency.(3)The standardized average weight diameter of the salt-irrigated water-clear water alternate irrigation test at the same depth is slightly higher than that of the irrigation using only salty irrigation water,but is significantly higher than the experiment using only pure water irrigation.There is no significant difference in soil bulk density and total porosity between the salt-irrigated water-clear water alternate irrigation test and the pure salt irrigation water irrigation test at the same depth,while the bulk density of the pure water irrigation test is significantly larger than the total porosity.It is obviously small.In the experiments under the salt-irrigated water-clear water alternate irrigation mode,the irrigation water infiltration time was the shortest under the same irrigation times,and the lateral preferential flow structure and the soil column priority were tested in the salt-irrigated water-clear water alternate irrigation mode.The flow structure has the smallest bending coefficient.The research results have reference value for the design of irrigation water farmland irrigation system.