Study On Soil Moisture Movement Law Of Biogas Slurry Indirect Drip Irrigation

Indirect underground drip irrigation technology is an irrigation technology that can quickly introduce water to the roots of crops.The irrigation part is composed of two parts of the water-conducting medium and the dripper.It has the advantages of suitable large dripper flow,reducing surface evaporation and integration of biogas slurry..This study uses a combination of laboratory testing and numerical simulation.In the laboratory test,set three dripper flow rates(1L/h,2L/h and 4L/h),2 kinds of water-conducting media(sand and straw),2 kinds of infiltration liquid(water and biogas slurry with a concentration of 20%),The law of indirect subsurface drip irrigation moist peak movement,the shape change of the moist body and the distribution of soil profile moisture content were studied.And using HYDRUS-2D software for numerical simulation analysis,in order to provide a theoretical basis for the popularization and application of biogas slurry indirect underground drip irrigation technology.The main conclusions are as follows:(1)When the infiltration liquid is water,the wetting peak distance of straw and sand as the water-conducting medium are all affected by the height of the permeable boundary,the dripper flow rate and the infiltration time,the magnitude of the influence is: infiltration time> dripper flow rate >Permeable boundary height;vertical and horizontal wet peak transport distance and infiltration time,dripper flow rate,and permeable boundary height have a good power function relationship;the shape of the wetted body is elliptical;compared with sand,straw can effectively increase Horizontal wet peak migration distance.(2)When the infiltration liquid is biogas slurry with a concentration of 20%,the shape of the wetted body is a pear shape.The vertical and horizontal wetting peak migration distances increase with the increase of the dripper flow rate;the larger the dripper flow rate,the farther the vertical and horizontal wetting peak migration distances,and the dripper flow rate moves to the wetting peak The distance is greater in the vertical direction than in the horizontal direction.The ratio of the vertical and horizontal wet peaks decreases with time and eventually stabilizes;the vertical wet peak decreases with the increase of the permeable boundary height,and the permeable boundary height has little effect on the change of the horizontal wet peak.As the height of the permeable boundary increases,the larger the "pear" tail of the wetted body,the shallower the depth of the vertical water content line and the more uniform the water content distribution in the horizontal direction.Straw as the water-conducting medium is more conducive to the transport of horizontal wetting peaks than sand as the water-conducting medium.(3)The measured and simulated statistical analysis results of the moisture content of moist peaks and moist bodies in indirect underground drip irrigation under pure water conditions are: MAE?0.192 cm,RMSE?0.271 cm,-0.042?PBIAS?0.689,NSE?0.773.It shows that HYDRUS-2D can better simulate the process of indirect underground infiltration.The statistical values of moist peak and water content of indirect underground drip irrigation of biogas slurry are: MAE?0.034 cm,RMSE?0.271 cm,-0.042?PBIAS?0.689,0.962?NSE?0.773,indicating that HYDRUS-2D can simulate the biogas slurry better The whole process of water migration of indirect underground drip irrigation as infiltration liquid.