Factors Influencing The Uniformity Of Fertilization In Micro Spray Belt Irrigation

The micro spray belt can be used to spray water through the holes on the wall of thin-walled plastic hose,which has the advantages of low cost,large flow rate,good resistance to blocking,easy to lay and collect in the field,convenient maintenance,etc.it can integrate water and fertilizer,reduce the waste of water and fertilizer,and has a broad application prospect.The hydraulic performance and water distribution uniformity of micro spray belt are the important factors that affect the uniformity of fertilization in water and fertilizer integrated irrigation,but the research is not in-depth at present.Based on the experiment of uniformity and hydraulic performance of micro spray belt irrigation and fertilization under the integration of water and fertilizer,combined with the basic theory and experimental results of hydraulics,this paper analyzes the influencing factors of hydraulic performance and water distribution uniformity of micro spray belt,and further puts forward the more suitable field irrigation operation parameters of micro spray belt.The main conclusions are as follows:(1)The relationship of pressure and flow rate of different types of micro jet belts accords with power function.The discharge per unit length of the micro spray belt increases with the increase of the first working pressure.Under the same pressure,the discharge of the micro spray belt increases with the increase of the pipe diameter,but the increase of the flow rate slows down.The difference between ? 32 and ? 40 is smaller than that between ? 28 and? 32.The micro spray zone belongs to the discharge pipeline along the way,the pressure along the way is continuously reduced by the influence of head loss,which affects the uniformity of water distribution in the micro spray zone.The head loss is related to the working pressure of the head,the laying length and the pipe diameter of the micro spray belt.With the increase of the laying length of the micro spray belt in the field,the pressure difference between the head and the end increases continuously.In the field application of micro spray belt,the most suitable laying length and head pressure should be determined according to the structure of micro spray belt.(2)It is found that the larger the pipe diameter is,the larger the parameter index(range,width of wet area,etc.)of the water distribution of single hole is.The difference between the spraying angle of ? 40 and ? 32 with the working pressure is smaller than that of ? 28 and? 32,and the spraying width of ? 28 changes gently with the working pressure.The range of micro spray band single hole water spray increases first and then decreases with the spray angle,among which the maximum range is about 30 ° to 40 °;The range increases with the increase of working pressure,and the growth trend becomes slower when it is greater than40 k Pa;within a certain range(the spray angle is less than 45 °),the width of humid area is positively related to the spray angle and working pressure;The range and the width of dry area are changed with the spray angle The law is the same;When the spray angle is 50 °,the maximum value of the wet area appears.The width of the range of the three hole micro jet zone is the largest,the width of the range of the five hole micro jet zone is the smallest,and the difference between the seven hole micro jet zone and the three hole micro jet zone is small.It can be concluded that the uniformity of water distribution can be improved by properly increasing the number of holes.(3)Through the analysis of water distribution,it is found that there are peak value and dry area in the water distribution of micro spray belt;the relationship between water distribution uniformity coefficient and working pressure is not a single increase or decrease,but there is an optimal working pressure value.Under the condition that the laying length of the micro spray belt does not exceed 40 m,for example,the best operating pressure of the micro spray belt tested in this paper is between 32kpa-36 kpa.The uneven water distribution along the direction of micro spray belt is mainly caused by the pressure along the way and the discharge.We can choose the appropriate working pressure to improve the uniformity of water distribution by exploring the relationship between the head and tail pressure difference.At the same time,we should further explore the water change along the direction of micro spray belt under different length,and get the most appropriate laying length in actual operation;the water volume of micro spray belt in the vertical direction According to the location of the peak and the width of the drying area,the uniformity of irrigation can be improved by reasonably arranging the distance between the adjacent micro spray belts.(4)Through the experiment of uniformity of fertilizer application in the field of spring wheat water and fertilizer integrated micro spray belt,it is found that the influencing factors of uniformity of fertilizer application mainly include the type of fertilizer application device,working pressure,laying length,fertilizer type,pressure difference of fertilizer application device,etc.When the pressure difference type fertilizer tank is used for irrigation and fertilization,when the pressure difference of the fertilizer tank is 10 k Pa,the concentration of the fertilizer solution of the soluble fertilizer(such as urea)changes gently along the way and over time;the relationship between the pressure difference and the insoluble fertilizer(such as phosphate fertilizer)is not significant,and there is fertilizer stuck at the bottom of the fertilizer tank.When the proportional fertilizer pump is used,the uniformity of fertilizer application is higher than that of the differential pressure fertilizer tank in space and time;during the field irrigation and fertilization process,the water amount reaching the root of thecrop will be affected by the crop shelter,and the variation range of the concentration of fertilizer solution with the increase of the laying length slightly increases,and the concentration of fertilizer solution perpendicular to the direction of the micro spray belt is more uniform,with little change.According to the results of the yield test,the grain weight in the direction perpendicular to the micro spray belt decreased gradually from near to far,and the combination of multiple micro spray belts could reduce the uneven phenomenon of water and fertilizer.The uniformity of water and fertilizer in micro spray belt irrigation is mainly affected by the change of pressure along the way.The laying length of micro spray belt in field application should be determined according to the working pressure of the head and the pressure difference between the head and the tail,which should not be too long.