Blueberry Moistube Irrigation And Fertilization Model And Control System Design And Simulation

Moistube irrigation is a new underground continuous water saving irrigation technology based on principle of semipermeable membrane,and the water slowly transported to the crop root zone through the underground moistube and using water potential difference around the membrane.At present the moistube infiltration characteristics research focused on the horizontal layout,but the vertical insertion moistube infiltration characteristics reported less which is widely used in fruit trees and economic trees.In this paper,moistube infiltration experiment mainly through 3 water heads(1 m,1.5 m,2 m)and 3 soil textures(sand,sandy loam and loam)completely combination,the vertical insertion moistube infiltration rate,cumulative infiltration,wetted body volume and the characteristics of soil water content distribution were investigated.Moistube irrigation of blueberry planting experiment,using 3 moistube layout(vertical insertion layout LI,circular layout L2,horizontal layout L3)and 4 fertilization(0 g/plant FO,10 g/plant FI,20 g/plant F2,30 g/plant F3)completely combination,the effect of different irrigation and fertilization mode on blueberry growth index(plant height,stem diameter,leaf area,shoot),physiological indexes(net photosynthetic rate,transpiration rate,stomatal conductance,chlorophyll SPAD value),soil moisture,water use efficiency,dry matter quality were investigated:In addition,on this basis,the automatic control system based on PLC of moistube fertigation was designed.The main research contents andresults are as follows:(1)Effects of soil texture and water pressure on moistube infiltration of vertical insert modeThe initial infiltration rate increased with the increase of water head.The initial infiltration rate of loam was the largest,followed by sandy loam and sand.The change process of infiltration rate in different time was accorded with modiflied model of Horton.The cumulative infiltration was quadratic polynomial of irrigation time.The volume of wetted body increased with the increase of water head,the shape of wetted body was approximately pear-shaped,which was small top and big bottom.The growth rate of wetted body was relatively slow when the water head was low.The growth rate of wetted soil body reached the maximum in the first 4-6 hours after infiltration,and the change process conformed to lognormal distribution.Soil texture had significant influence on soil water content,but the effect of water head on soil water content was not significant.Soil water distribution uniformity of loam and sandy loam(>80%)was higher than that of sand(<70%).(2)The effects of moistube irrigation and fertilization mode on the growth and physiological characteristics of blueberryFertilization had no significant effect on soil moisture content in different soil depths of blueberry root zone,moistube irrigation mode had a significant effect on soil moisture content in the blueberry root zone above 25 cm,the interaction of moistube irrigation mode and fertilization had significant effect on soil moisture content above 30 cm.Moistube irrigation mode and fertilization,as well as their interaction had significant effect on leaf number,total leaf area,plant height,shoot length per plant.The optimal combination of moistube irrigation mode and fertilization level to improve the blueberry leaf number,total leaf area,plant height and shoot length was L2F2.There was no significant effect of moistube irrigation mode and fertilization on the stem diameter of blueberry.Under different blueberry growth cycles,when the fertilization level was F2,the moistube irrigation mode was L2,the chlorophyll SPAD value of blueberry leaves was the highest.The chlorophyll SPAD value of blueberry leaves in mature stage was higher than that in flowering and fruiting stage.The diurnal variation of net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)ofblueberry leaves under different treatmentswere basically presented a double-peak with peak at 11:00,15:00,valley at 13:00.The most significant effect on the accumulation of dry matter mass of blueberry was the moistube irrigation mode of L2,the fertilization level of F2.(3)Design and simulation of blueberry moistube fertigation control system based on PLCOn the basis of moistube infiltration experiment and moistube irrigation blueberry planting experiment,according to the characteristics of moistube irrigation technology and environment conditions in remote wild areas,a set of automatic control system of moistube fertigation based on Internet was developed.The control system of moistube fertigation,overall structure and irrigation pipe network was developed,the main hardware equipment was selected,including temperature sensor,soil moisture sensor,rainfall sensor,light sensor,flow sensor,liquid level sensor,pressure sensor,weighing sensor,electric ball valve,submersible pump,wireless bridge,PLC,pressure reducing valve,and the PLC program flow chart was designed,the control program was written,and the program is verified by simulation experiment.According to the soil moisture content and the crop growth cycle,the water pressure can be adjusted automatically,so as to ensure the appropriate moisture content of the crop root zone.Mositube irrigation achieved irrigation and fertilization process automation and saving labor intensity.