Comparative Study On Negative Permeability Performance Of Two Different Material Seepage Emitters

The soil moisture in the negative pressure irrigation is a non-saturated state movement,which is the moisture movement driven by the matrix potential,and the soil water vapor condition is more coordinated,which has the potential to improve the crop productivity greatly.Among them,the negative pressure water infusion as an important medium to connect the negative pressure irrigation system and soil,the negative pressure irrigation uniformity and uniformity play a vital role.However,the current laboratory and residential tests commonly used in the negative pressure water seepers are mostly ceramic head or ceramic plate,there are high prices,easy to plug,tough brittle,low repetition rate and many other issues,not suitable for large-scale promotion.PVFM is a non-ionic polymer material with high hydrophilicity,high mechanical strength,good chemical stability and biostability,cell size and cell density.The porosity is easy to adjust and so on,and its water absorption characteristics by the environment of acid,alkali,temperature is much smaller,theoretically in complex environments(such as soil)as a moisture-sensitive sensors and drives.However,at present the material is rarely applied to the field of water-saving irrigation,only Cong Ping and other analysis of the different ratio and specifications of PVFM as a negative pressure water infiltration material used in negative pressure irrigation system feasibility,with a simple indoor water transport The PVFM negative pressure irrigation water seepers were not applied to the actual crop cultivation.PVFM modification also changed the cell size and quantity of the PVFM water permeator only from the physical point of view,without adding the chemical modifier Perform related modification tests and performance analysis.Therefore,this paper attempts to improve the performance of PVFM water permeation and the traditional clay water permeator by the pot experiment and the pot experiment.The tests include: 1,Preparation of silane The tensile strength,the hardness,the elongation at break,the saturated hydraulic conductivity and so on.(2)The PVFM water permeator and the clay water permeator were observed.The PVFM was tested by the coupling agent and the polysulfide rubber.3,the pot experiment was conducted to observe the effects of PVFM infiltration and clay permeation on the growth and development of spinach in negative pressure irrigation,and the effects of water infiltration and water consumption on the growth and development of spinach in different soil layers of chernozem 4,observed the PVFM water seepers and clay water in the soil performance evolution process.After the above test and comprehensive analysis,this paper has the following main conclusions:(1)PVFM and clay two kinds of material water infiltration in different soil cumulative infiltration and wetting peak,the infiltration rate and the wetting peak countdown,wet peak square and the infiltration time have a clear linear relationship between the irrigation after the distance from the water The soil moisture content is maintained at 20% ~ 33% in 15 cm range.Kostiakov and Philip infiltration model can describe the water infiltration characteristics under-5kPa negative pressure irrigation.(2)The effects of different burial depth and different burial time on the foaming point value,saturated hydraulic conductivity,water absorption ratio and rebound performance of PVFM water seepers were different.In general,the buried depth is 10 cm and the burial time is less than 40 days.The performance of PVFM water seepers is better,while the performance of clay water permeator is better when the burial depth is 20 cm and the burial time is less than 20 days.Physical performance,water permeability and rebound performance performance,PVFM water permeability performance is better than clay water seepers.(3)Maintaining the soil water content by negative pressure irrigation technology is basically stable and efficiency.Negative pressure irrigation can significantly affect the agronomic traits of spinach,and negative pressure irrigation is conducive to the growth of spinach than conventional irrigation between-8 ~-4kPa.Between the two emitters,PVMF is more advantages.Negative pressure irrigation can significantly improve spinach yield,quality and water use efficiency.The optimal treatment was W2P(-8kPa,PVFM),which was 59% higher than CK in the yield,35.9% lower in water consumption,88.3% higher in WUE.Phosphorus and potassium absorption is higher than other treatments;Different crops need to select the appropriate negative pressure irrigation conditions in order to achieve water saving,fertilizer,the purpose of increasing production.(4)Different metering modifiers have different effects on the foaming point,saturated hydraulic conductivity,cumulative infiltration amount,hardness,elongation at break and microstructure of PVFM.The use of 5.0% liquid polysulfide rubber modified PVFM can effectively improve the foaming point and mechanical properties of materials to ensure negative pressure seepage performance and improve the operation stability of the water infusion device under negative pressure conditions and soil environment.