Study On Infiltration Characteristics Of Underground Infiltration Irrigation And Its Effect On Saving Water And Increasing Production Of Jujube Trees

In order to promote the precise irrigation of fruit forests in arid areas,help the adjustment of the agricultural industry structure,and effectively improve the yield and water use efficiency of fruit forests,this paper takes the Tongxinyuanzao’jujube as the research object,by studying the infiltration characteristics of underground infiltration irrigation and the effect of increasing water-saving and output of jujube trees,determining the processing technology and laying method of underground infiltration irrigation pipe,exploring in depth of underground infiltration irrigation on jujube trees’ water consumption law,root distribution,soil moisture changes and the field application technical parameters of infiltration irrigation pipe,fully analyzed the mechanism of drought resistance,water saving and yield increase by the underground infiltration irrigation.The main conclusions are as follows:(1)The physical properties of the underground infiltration irrigation pipes under different processing conditions,the results show that more rubber particles,low processing temperature,and strong tensile strength can increase the density of seepage holes in underground infiltration irrigation pipe.The influence of the processing temperature on the water absorption time and expansion rate of the underground infiltration irrigation pipe is greater than that of the raw material ratio and tensile strength.The processing temperature has little effect on the seepage volume of underground infiltration irrigation pipe,and there is a very significant difference in seepage volume under different raw material ratio conditions(P<0.01).From the perspective of the manufacturing deviation coefficient of underground infiltration irrigation pipe under different pressures,the treatment T2P3L1(rubber powder:polyethylene is 2.86,processing temperature is 151℃,tensile strength is 5 N)and the treatment T2P1L2(rubber powder:polyethylene is 2.50:1,processing technology temperature is 151℃,tensile strength is 10 N)performance is the best.(2)Through the study of infiltration characteristics and water transport law of underground infiltration irrigation,the results show that when the pressure range is 0.02-0.08 MPa,the rated flow rate of the underground seepage irrigation pipe after the water seepage is stable is 1.42～4.93 L/(min·m);the greater the pressure,the greater the rated flow,the longer the underground infiltration irrigation pipe,the lower the average rated flow.The shape of the wetting body of the underground infiltration irrigation pipe is an elliptical cylinder centered on the underground infiltration irrigation pipe,which gradually increases with time.The seepage rates under different pressures are vertically downward>horizontal>vertically upward,and the moving distance of the wet front has a power function relationship with irrigation time,and the correlation coefficients R2 are all above 0.99.The application parameters of underground infiltration irrigation pipe in two kinds of soil have been determined,among them,the laying depth of underground infiltration irrigation pipe in sandy soil is 15～30 cm,and the radius is 30～40 cm;the laying depth of infiltration irrigation pipe in sandy loam is 30～45 cm,the radius of 40～50 cm is more suitable.(3)Combining meteorological factors to analyze the relationship between underground infiltration irrigation and the water consumption law of jujube trees,the results show that different treatments have a significant effect on the water consumption and daily water consumption intensity of jujube trees during each growth period.In the same growth period,there was a positive correlation between irrigation amount and daily average water consumption intensity;under the same treatment,the crop water consumption and daily average water consumption intensity of each growth period increased first and then decreased.The fruit expansion period was the peak water consumption period of jujube tree;The trees crop coefficient generally showed a trend of increasing first and then decreasing,and the peak value appeared during the fruit expansion period.(4)According to the microporous characteristics of water infiltration,the effects of different laying methods of underground infiltration irrigation pipes on soil moisture and root distribution of jujube trees were studied,the results show that the soil moisture content increased with the buried depth of underground infiltration irrigation pipe.The maximum distribution range of soil moisture content and the center of wetting body both move downward;with the increase of the laying radius of underground infiltration irrigation pipe,the maximum distribution range of soil moisture content and the peak of wet front move outward;as the amount of irrigation increases,the range of wetting body is gradually increased.The root dry mass density of each treatment in the vertical 40～60 cm soil layer is the largest,with an interval of 176.38～181.04 g/m3,accounting for 28.65%～30.12%of the total root dry mass density of the 0～200 cm soil layer.The root dry mass density increments in the horizontal direction are mainly distributed in 20～80 cm,and the root dry mass density in 20～40 cm is the largest,with an interval of 129.58～133.24 g/m3,accounting for 24.66%～26.01%of the root dry mass density of 0～200 cm soil layer in the horizontal direction of jujube tree.(5)Study the effects of different underground infiltration irrigation pipe laying methods and irrigation amount on the growth and development of jujube trees,,the results show that the yield of treatment D30R30W0.8(buried depth of underground infiltration irrigation pipe D30,laying radius R30 and crop dish coefficient W0.8)was the highest,and the 3-year jujube outputs was 7600.49,7758.15,and 7394.71 kg/hm2 respectively;the highest irrigation water utilization efficiency was 3.15,3.04,and 3.01 kg/m3 respectively;the highest water use efficiency is 3.37,3.44,3.31 kg/m3,which are significantly different from other treatments(P<0.05).(6)The principal component analysis and the TOPSIS model evaluate the comprehensive benefits of various indicators of jujube tree,and all of them show the treatment D30R30W0.8 is the best.Therefore,the best way to determine the layout of jujube trees of underground infiltration irrigation pipe in the arid area of Ningxia is as follows:the buried depth of the ground is 30 cm,the trunk is the center and the center is 30 cm outward,and the irrigation amount is the crop coefficient 0.8,It reveals the effect of underground infiltration irrigation on water-saving and yield-increasing of jujube trees in arid areas.