滴头流量对不同质地棉田土壤湿润区的影响研究OA

In order to clarify the soil wetting front and changes in soil water,salt and temperature in cotton fields under drip irrigation tapes with different flow rates,drip simulation studies were carried out on sandy and clayey soils by selecting drip irrigation tapes with 1.1 L·h-1(small flow rate),2.6 L·h-1(medium flow rate)and 3.2 L·h-1(large flow rate).The results showed that soil conductivity and volumetric water content at 1.1 L·h-1,2.6 L·h-1 and 3.2 L·h-1 flow rates followed the same trend for the same drip time on sandy and clayey soils.In the horizontal direction,the conductivity showed a decrease from the periphery towards the drip head,with the sandy soil showing the largest decrease of 91.03％at 1.1 L·h-1 flow rate,and the clay soil also showing the largest decrease of 87.38％at 1.1 L·h-1 flow rate.Vertical direction decreases from deep to surface with maximum 93.91％decrease in sandy soil at 1.1 L·h-1 flow rate and 83.93％decrease in clay at 2.6 L·h-1 flow rate.In contrast,the trend of soil volumetric water content in the horizontal and vertical directions is opposite to that of electrical conductivity,with negative correlation.The sandy soil has a maximum wetting front transport distance of 35.0 cm horizontally at 2.6 L·h-1 flow rate and 20.0 cm vertically at 3.2 L·h-1 flow rate,while the clay soil has a minimum wetting front transport distance of 27.0 cm horizontally at 1.1 L·h-1 flow rate and a maximum wetting front transport distance of 15.0 cm vertically at 1.1 L·h-1 flow rate.The shape of the wetted zone is nearly semicircular(narrow and deep)in sandy soils and nearly elliptical(wide and shallow)in clayey soils.The angle between the horizontal and vertical wetting fronts at 1.1 L·h-1 flow rate and the horizontal wetting front is 47.98° for clayey soils and 51.34° for sandy soils at 3.2 L·h-1 flow rate.Combined with the wetting fraction transport distance,a comprehensive analysis shows that sandy soils have deep vertical infiltration and small horizontal diffusion at a flow rate of 3.2 L·h-1,while clay soils have a large infiltration depth and small surface diffusion at a flow rate of 1.1 L·h-1,which is conducive to the reduction of surface runoff.Therefore,it is recommended to select high flow drip irrigation tapes for sandy soils and low flow drip irrigation tapes for clayey soils in order to provide reference for precision irrigation of cotton fields in the division.