果园仿形变量喷雾与常规风送喷雾性能对比试验

为深入研究不同果园喷雾机的喷雾性能及影响规律,探究仿形变量喷雾技术在果园植保作业中的适应性,该文采用一种基于(LiDAR)扫描探测技术的果园自动仿形变量喷雾机,与常用的传统风送果园喷雾机、定向风送喷雾机进行对比,分析了3种机具的主要喷雾指标:药液消耗、冠层内部沉积、仿形喷雾效果、地面流失及空中飘移.试验结果表明:与常规喷雾方式相比,仿形变量喷雾有效地提高了农药利用率和作业效率,最多可节省药液45.7％;传统和定向风送喷雾机纵向沉积呈现从上部到下部逐渐增加的趋势,仿形变量喷雾机能够根据树冠特征实时调节喷雾参数,纵向沉积呈仿形分布;与传统风送喷雾机和定向风送喷雾机相比,仿形变量喷雾机的雾滴飘移分别减少23.2％和42.7％,地面流失分别减少67.4％和58.8％.该研究为果树病虫害防治减量施药提供新方法与新装备,为精准植保机具的结构设计和性能优化提供参考.

Comparative experiment on profile variable rate spray and conventional air assisted spray in orchards

At present,most of air assisted orchard sprayers adopt the continuous spray operation method,resulting in significant loss of pesticides and contamination of the environment.In order to improve the automatic working performance of orchard sprayer,an automatic profiling orchard sprayer based on LiDAR (light detection and ranging) sensor was developed.Electromagnetic valve and brushless fan were adopted as actuators to control the flow rate and air volume based on the pulse width modulation (PWM) signals.The flow rate and air flow could be controlled by the controller based on the canopy volume and leaf density.To explore the variable rate prototype's application effects,2 conventional orchard sprayers with central fan were selected as reference sprayers for comparison in this paper.The first type was a conventional air blast sprayer (CABS),which was the most widely used in China;the second reference machinery was a directed air-jet sprayer (DAJS) equipped with a centrifugal fan and 4 individual air spouts on each side,connected to the air outlet by flexible ducts.DAJS had the multi-degree of freedom framework,and nozzle position could be adjusted according to canopy characteristics,and achieve the directional spraying.Through comparative field experiment on the performances of the 3 types of sprayers,the dominant factors controlling spraying quality,including liquid consumption,droplets deposition distribution in canopy,profiling spray effect,loss on ground and drift in air,were analyzed.The field experiments were conducted in an apple orchard in Beijing,a research farm belonging to the China Agricultural University.The trees' row spacing was 4 m × 2 m,the average height of trees (pruned) was 3.8 m,and the canopy diameter was 2.1 m.Tartrazine (2.5‰) was chosen as the tracer material and metallic screens (2.5 cm × 7.5 cm) with mylar cards (10 cm × 10 cm) were adopted to receive the droplets.Based on tree height,width and depth,each target tree was divided into sampling sections.In each section,metal wire screen was attached to the sampling sites.Nine mylar cards were placed on the ground under canopies and gaps between trees to evaluate deposition loss on the ground.To test the spray drift,a frame with metal wire screen was located on the row behind the tree at the far side of spraying.Fifty typical leaves were collected randomly from different parts of trees,and their surface area (one side only) was measured with a leaf area meter to determine the average surface area of leaves.The number of leaves was counted according to the layout of the sample collectors and combined with the average area;the average total leaf area per height section of 0.35 m was calculated.The point was to understand the leaf distribution to check the profiling spray effect.The results showed that compared to the other 2 conventional sprayers,variable rate sprayer application in the orchard saved up to 45.7％ of the solution.Normalized deposition on the canopy using variable rate sprayer was higher than conventional application,which indicates that the electronic sprayer is more efficient than conventional sprayers.In case of CABS,deposition at the bottom parts was higher than the upper parts due to radial spray pattern.Deposition distribution for DAJS at different heights was similar,except the heights at the same level of spouts.Variable rate application followed an arc line,with the highest deposition in middle parts,which generally presented better profile modeling spray adaptive to leaf area distribution.Also,variable rate application could reduce off-target losses,with 23.2％ and 42.7％ reduction in the air and 67.4％ and 58.8％ reduction on the ground respectively compared with CABS and DAJS.The results of the comparative test and the analyses of the 3 types of sprayers,provide the basis for theoretical research and optimized design of plant protection equipment,and also offer the new method for research and development of precision application machinery.Moreover,the study provides better references for popularization and application of these kinds of sprayers.