Optimization Of Furrow And Ridge Cultivation Measures In Inland River Source Irrigation Area Based On Soil Wetted Body

In order to improve the utilization rate of water resources and ensure the stable development of agricultural production,in recent years,the combination of traditional surface drip irrigation and furrow ridge mulching cultivation has gradually appeared in the inland river source irrigation area of China.The wetted area(wetted body)formed by drip infiltration is an important reference for judging the quality of irrigation.Many scholars at home and abroad have been devoted to exploring the mechanism of soil water movement under drip irrigation.However,most of the previous researches on the rule of drip irrigation infiltration and the model of moisture peak transport distance were based on the crop flat cultivation mode,which did not fully consider the combination with other cultivation modes.Therefore,it is of great significance to study the infiltration process of drip irrigation under the condition of furrow and ridge cultivation.In this paper,the effects of furrow ridge cultivation and flat cultivation on the size and shape of soil wetted body,the wetting ratio and the distribution of water in the soil wetted body after the end of irrigation were studied through the soil box simulation experiment.The effects of the width of the ditch bottom,the bulk density of the soil,the flow rate of the dripper and the initial water content of the soil on the characteristic values of the soil wetted body were analyzed.The four effects were established Based on the empirical model of moisture peak transport distance under the condition of factors and the root distribution characteristics of 3-year-old Lycium chinensis,the furrow ridge cultivation measures were optimized.The main research results are as follows:(1)Under the condition of furrow and ridge cultivation measures,the soil wetted body formed by drip irrigation with single point source on the surface is mainly composed of two parts below and above the furrow bottom plane,in which the wetted body under the furrow bottom plane is 1/4 elliptical as the research focus.As the width of ditch bottom increases,the wetting range of surface soil is wider,the volume of wetted body is larger and the shape of wetted body becomes flatter.(2)The wetting ratio is larger at the initial stage of water infiltration.With the prolongation of irrigation duration,the wetting ratio under different treatment conditions of furrow bottom width decreases sharply within 20 min-80 min and tends to be gentle after 100 min.After irrigation,it is under 1.0.The wetting ratio is positively correlated with the width of trench bottom.The larger the width of trench bottom,the larger the wetting ratio.(3)After irrigation,the soil water content reaches its maximum at the position of the drip head.With the increase of spacing between the drip head and the drip head in the horizontal and vertical directions,the soil water content presents a gradually decreasing trend.The contour distribution map of water content is similar to the basic contour characteristics of the shape map of the wetted body under the corresponding test conditions,showing a distribution pattern from dense to sparse.The larger the width of the ditch bottom,the larger the horizontal part of the high water content in the soil,i.e.the center of gravity of water distribution in the wetted body gradually increases with the increase of the width of the ditch bottom,while the change of the width of the ditch bottom has relatively weak influence on the vertical water infiltration.(4)With the increase of initial soil water content,the horizontal migration distance and vertical infiltration depth of the wetting peak increase during the same irrigation time;the increase of drip head flow promotes the migration and infiltration of the wetting peak;the horizontal migration distance of the wetting peak is positively correlated with the soil bulk density,while the vertical infiltration depth of the wetting peak is negatively correlated with the soil bulk density;The change of width has a significant effect on the horizontal transport of the wet peak.(5)Under furrow and ridge cultivation conditions,the horizontal migration distance and vertical infiltration depth of the wetting peak of single point source drip irrigation on the surface are power-function relation with water infiltration time t,and the power-function index coefficient in horizontal direction is 0.29 and power-function index coefficient in vertical direction is 0.45.The infiltration coefficient has good linear relationship with soil bulk weight,ditch bottom width,drip head flow rate and initial soil water content respectively.The fitting coefficient is above 0.91,and the fitting effect is ideal.(6)An empirical model of wetting peak transport distance was established under the combined action of four test elements,namely,soil bulk density,ditch bottom width,drip head flow rate and initial soil water content.Based on the root distribution range of 3a-year-old Lycium chinensis planted in the field,the furrow and ridge cultivation measures were optimized.The optimum width of furrow bottom for Lycium chinensis planting in inland river source irrigation area was 26.90 cm.