Outdoor Experimental Research On Soil Water And Salt Transport Characteristics Under Brackish Water Film Hole Irrigation

Combined brackish water with film hole irrigation can give full play to the advantages of both,to a certain extent,this new type of irrigation playing a water-saving effect.Therefore,it is necessary to study the rules of soil water and salt movement under the condition of field experiment.Based on the related literature about brackish water and film hole irrigation from the home and abroad,this paper use the technical route including both experiment and theoretical analysis.Through outdoor infiltration experiments of brackish water film hole irrigation,studies the soil moisture and salt transport and redistribution characteristics under brackish water film hole irrigation.The main research results are as follows:1.This paper studies the effect of irrigation technique elements on soil moisture and salt transport and redistribution under brackish water film hole irrigation,irrigation technique elements include irrigation quantity and film hole diameter.The results show that irrigation technique elements have a great impact on soil moisture and salt transports and redistribution.Irrigation quantity increases,soil vertical wetting front transports deeper.Soil moisture is larger as the irrigation quantity increases at the same position.And the electrical conductivity of soil surface reduces as the increases of the electrical conductivity of deep soil with the irrigation quantity increases.Soil moisture of soil surface increases and soil moisture of deep soil decreases as film hole diameter increases.Electrical conductivity of soil surface is smaller and electrical conductivity of deep soil is larger as film hole diameter increases.The redistribution process does not affect the effect of irrigation technique elements on soil water and salt transport.2.This paper studies the effect of brackish water quality on soil moisture and salt transport and redistribution under brackish water film hole irrigation,brackish water quality includes salinity and sodium adsorption ratio two elements.The results show that brackish water quality do have a great impact on soil moisture and salt transports and redistribution.The ability of soil water transmitting is the highest when salinity is 3 g/L,and the ability reduces with the increases of salinity.When salinity is smaller than 3 g/L,there exists salt reducing area,but when salinity is bigger than 3 g/L,there doesn't.Sodium adsorption ratio increases,soil vertical wetting front reduces.Soil moisture is larger with sodium adsorption ratio increases at the same position.Sodium adsorption ratio do not have impact on salt transports and distribution under brackish water film hole irrigation.The redistribution process does not affect the effect of brackish water quality on soil water and salt transport.3.This paper studies the effect of fractional irrigation on soil moisture and salt transport and redistribution under brackish water film hole irrigation,fractional irrigation includes irrigation order and irrigation time.The results show that fractional irrigation do have a great impact on soil moisture and salt transports and redistribution.The first irrigation water quality plays a leading role in soil moisture and salt transport and distribution.Soil vertical wetting front transports deeper when the first irrigation water is brackish water.Between brackish water-fresh water and fresh water-brackish water,when irrigation order is brackish water-fresh water,middle soil's electrical conductivity is higher than the other one,and when irrigation order is fresh water-brackish water,soil surface and deep soil's electrical conductivity is higher than the other one.When the fresh water irrigation time extends from 0h to 12 h,soil moisture increases at the same position,electrical conductivity of soil surface reduces as the increases of the electrical conductivity of deep soil at the same position.When the fresh water irrigation time extends from 12 h to 72 h,the rules of soil moisture and salt transport and distribution are opposite.The redistribution process does not affect the effect of fractional irrigation on soil water and salt transport.This paper realizes the impact of irrigation quantity,film hole diameter,salinity,sodium adsorption ratio,irrigation order and irrigation time of fresh water on on soil moisture and salt transport and distribution under brackish water film hole irrigation.These results provide theoretic proof for developing brackish water film hole irrigation.