Experimental Study On Factors Effecting Soil Wetted Body Of Clay Loam Under Bubbed Root Irrigation

The effects of initial soil water content, soil bulk, density, emitter depth and sleevelength on moist body shape, size, wetting front and soil moisture distribution during bubbleirrigation were investigated using repacked soil boxes. Proposed a relatively simple empiricalmodel of bubble irrigation filling the soil moisture characteristic value, and provides a basisfor bubble-irrigation system design and operation management. And the preliminary researchresults were obtained as follows:(1) Empirical equations were derived by fitting the initial water content, soil bulk density,emitter depth, casing length with the maximum horizontal wetted radius and vertical wetteddepth. The shapes of soil wetted zone under different initial soil water and soil bulk densitywere similar but eigenvalue of wetting were different. As time changes in the amplitude isgradually slowing down. Emitter depth had significant effect on the surface wetted radius andvertical wetted depth. The greater emitter depth is, the surface wetted radius is smaller, thevertical wetted depth is greater. Casing length had significant effect on the shapes of soilwetted volume. With the casing length increases the wetted soil zone from the verticalellipsoid becomes more flat long, horizontal direction wetted distance and vertical distanceratio went down.(2) Cumulative infiltration iecreased along with increasing the initial water content orsoil bulk density. Cumulative infiltration decreased along with increasing soil bulk density.(3) If there were no evaporation or small evaporation, the wetting front advance rate isless than0.2cm/h48h after the end of irrigation, at this time, the wetting front advance rate isso small that the soil water redistribution is mostly ended.(4) The higher initial water content is, the water amount and the wetted soil zone ofwetting body is higher after48h at the end time of drip source infiltration, the effective watermeet crops continuously is more. The higher initial water content plays an important role inimproving the average moisture content of wetting body. Soil water content went down alongwith increasing soil bulk density48h at the end time of drip source infiltration。(5) With the increase of the emitter depth, wetting soil moisture zone significantly shifteddownward, the surface moisture zone is also significantly reduced, the vertical wetted depth isincreased significantly. It plays a significant role in the control of crop surface evaporation. In the case of emitter flush depth with the soil surface, the surface wetted radius is so larger andthe vertical wetted depth is so shallower that irrigation effective is less. With the increase ofthe casing length, the vertical direction increases with the casing length, there was significantdifference in the vertical moist distance. The longer casing is, the vertical moist distance isdeeper after redistribution of wetting body. In the case of the same surface moist range, thelonger casing is, high moisture content and the range of wetted is larger. The shapes of soilwetted zone in the group of casing length length larger is narrowed and darken than the groupof casing length length smaller.