Simple decision-making model for orchard air-assisted spraying airflow

Airflow speed is one of the three factors of air-assisted spraying.Optimizing the matching model between airflow speed and target canopy characteristics is an effective way to improve the orchard precision spraying technology,as airflow can significantly affect droplet deposition and drift loss.A simple model of airflow speed was established in this study.First,air-assisted spraying experiments were carried out on a standard simulation canopy to study the airflow speed depended on canopy width,leaf area index,and porosity rate.Second,determined by Ribbon Method and verified by droplet drift data,the airflow speed through the canopy was between 0.5 m/s and 0.7 m/s.Third,multiple tests were carried out under standard simulation canopy with different characteristics,and the airflow speed model was established ultimately:with a fixed leaf area index(LAI),the relationship between canopy upwind boundary airflow speed and canopy width satisfied the exponential model(y=ae^(bx)),and the coefficients a and b are well related to the density of branches and leaves in the canopy.When LAI=3.456,y=2.036e^(1.5887x),R^(2)=0.994;LAI=1.728,y=1.639e^(1.445x),R^(2)=0.972.Orchard growers can acquire needed airflow speed through this simple model,it is quick and precise and appropriate to most growth periods of a variety of fruit trees,such as apples,pears,and vines.

Effect of aerial spray adjuvant applying on the efficiency of small unmanned aerial vehicle for wheat aphids control

Small unmanned aerial vehicles(UAVs)have been widely used in different aspects of modern farming management,including pest and disease control in China in recent years.In this study,the spray performance of a small plant protection UAV at low volume spray was evaluated by adjusting the pesticide dosage and adding aerial spraying adjuvants.Droplet deposition,droplet density,coverage,control effect and pesticide residue from field trials were assessed.In addition,the residue and control effect of UAV spray were compared to manual knapsack at high volume spray.The results showed that,the adjuvant applying improved the efficiency of UAV spray.Also,the adjuvant applying reduced the dosage of imidacloprid by 20%.However,there was no significant difference on initial residue between UAV spray and knapsack spray.Thus,plant protection UAV spraying pesticide by adding appropriate adjuvant showed the ability of improving the pesticide effectiveness by improving the control efficiency,reducing the pesticide dosage and residue.

Design and experiment of variable rate orchard sprayer based on laser scanning sensor

During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.

Drift potential of UAV with adjuvants in aerial applications

The reduction of pesticide aerial spraying drift is still one of the major challenges in modern agriculture.The aim of this study was to evaluate the drift potential of different types of unmanned aerial vehicle(UAV)and adjuvant products for reducing spray drift in aerial applications.Three types of UAV(3WQF120-12 and 3CD-15 fuel oil powered single-rotor UAV and HY-B-15L battery powered single-rotor UAV)were selected in this study with regular application parameters to compare each spray drift,and 3WQF120-12 fuel oil powered UAV was selected to quantify spray drift of 6 adjuvants dissolved in water under field conditions.Solutions were marked with brillant sulfoflavin dye(BSF)at 0.1%.Petri dishes and rotary impactors were used to collect airborne and sediment drift,respectively.Drift deposits were evaluated by spectrophotometry in order to quantify deposits.The results showed that when the flight height was 1.5-2.0 m above the crop at the flight speed of 4-5 m/s and the average wind speed of 1.63-1.73 m/s,3WQF120-12 fuel oil powered UAV had lower drift potential than the other two types;DV0.5 and percentage of droplets with diameter≤75μm had very significant effects on spray drift percentage(p=0.01);the risk of drift in agricultural spraying could be significantly decreased not only by reducing the percentage of fine droplets but also by changing droplet spectra.Compared to water,Silwet DRS-60,ASFA+B,T1602,Break-thru Vibrant,QF-LY and Tmax could reduce by 65%,62%,59%,46%,42%,and 19%spray drift,respectively.when water without adjuvants were sprayed,90%of drift droplets were located within a range of 10.1 m of the target area while with 0.8%Silwet DRS-60 adjuvant in water,the distance was shortened to 6.4 m.

Spray drift characteristics test of unmanned aerial vehicle spray unit under wind tunnel conditions

Since the 2010s,unmanned aerial vehicle(UAV)sprayer was applied more and more widely for low-volume aerial pesticides spraying operations in China.However,droplets from the UAV sprayer have a higher drift risk due to more fine droplets sprayed and a higher flight height than ground sprayers.Study on UAV spray drift has been a new hot spot within the field of pesticide application technology.Most of previous studies used direct field methods for spray drift,but the meteorological conditions in field were unstable and uncontrollable,and drift research under an actual operation state in wind tunnel has not been reported.Therefore,25 treatments of wind tunnel measurements and droplets spectrum tests of 10 models of nozzles were conducted to explore the influence factor on spray drift characteristics of UAV chemicals application in this study.A spray unit with a rotor of UAV was innovatively installed in wind tunnel,and the airstream from the wind tunnel was regarded as the relative moving natural wind to simulate the flight status.The airborne and the sediment spray drift was measured to study the effects of the nozzle type and size(flat fan,hollow cone and air-inclusion nozzles),flight speed,adjuvant(DRS-60,Y-20079,MF and G-611)and meteorological parameters(20°C&40%,20°C&80%,30°C&40%and 30°C&60%).The drift potential(DP)and the drift potential reduction percentage(DPRP)in vertical and horizontal directions were obtained for each test.Both nozzle type and size had an impact on the spray drift potential obviously by affecting the droplet size and the ratio of fine droplets,and the regression linear models between DPRPV/DPRPH and DV50,V75 were established(R2=0.934/0.925).Flight speed also had a significant effect on the spray drift characteristics,and reducing the flight speed could increase the DP effectively.Adding spray adjuvants could affect the DP under experimental meteorological parameters,and the anti-drift performance ranked in the order of DRS-60>MF>Y-20079>G-611.Recommendations were proposed in order to reduce the spray drift for UAV sprayer’s operation.These findings can contribute to provide guidelines and technical support for the wind tunnel spray drift tests of UAV and the field operation regulation of unmanned aerial PPP application.

Reducing residues of tetracycline and its resistance genes in soil-maize system and improving plant growth:Selecting the best remediation substance

Tetracycline(TC)and tetracycline resistance genes(TRGs)in plant edible tissues pose a potential risk to the environment and then to human health.This study used a pot experiment to investigate the effects of different remediation substances(worm castings,fungal chaff,microbial inoculum,and biochar)on the physiological characteristics of maize and the residues of TC and TRGs in the soil-maize system under TC stress.The results showed that TC significantly inhibited growth,disrupted the antioxidant defense system balance,and increased proline and malondialdehyde contents of maize plants.Tetracycline residue contents were significantly higher in root than in shoot,and followed the order root>stem-leaf>grain,which was consistent with the distribution of bioconcentration factors in the different organs of maize plants.The TC residue content in the soil under different treatments was 0.013–1.341 mg kg-1.The relative abundances of different antibiotic resistance genes in the soil-maize system varied greatly,and in maize plants followed the order intI1>tetW>tetG>tet B>tetM>tetX>tetO.In the soil,tetX had the highest relative abundance,followed by tetG and tetW.A redundancy analysis(RDA)showed that TC was positively correlated with TRGs.The addition of different remediation substances alleviated the toxicity of TC on maize physiological characteristics and reduced the TC and TRG residues in the soil-maize system,with biochar being the best remediation substance.These results provide new insights into the effect of biochar on the migration of TC and TRGs from soil to plants.

Effects of xanthan gum on atomization and deposition characteristics in water and Silwet 408 aqueous solution

In order to investigate the effects of viscosity on spray formation and utilization of pesticide,different concentrations of xanthan gum(XG)were added into water and 0.1%Silwet 408 aqueous solution.Droplet size,relative span(RS),fan angle,length of breakup and maximum retention(Rm)were measured with the LU120-02 nozzle spraying under the pressure of 0.3 MPa.The dynamic spreading of the different solutions on maize leaves was tested using a 5μL micro-injector.The results showed:VMD,RS,length of breakup and Rm went up as the increasing of XG concentration in the range of 0-0.5%with the same solution,while the fan angle of nozzle and spreading area on maize leaf showed the opposite tendency.Silwet 408 could reduce the surface tension of liquid,which could alter the dominant mode of spray formation and lead to earlier sheet breakup,especially in low viscosity solutions.Under the same concentration of XG the addition of Silwet 408 could reduce the RS of drop size spectrum but has no effect on VMD or fan angle.In water solution,there was no difference with different concentrations of XG in the spreading time on maize leaf.Besides,in the 0.1%Silwet 408 aqueous solution,the spraying time and area were several-fold of that in water with same XG concentration.Moreover,with the same XG concentration,the smaller surface tension liquid indicated lower Rm,and the difference was magnified as the concentration increases.This work has demonstrated that initial spray characteristics such as droplet size and RS,fan angle,length of breakup,Rm and spreading area can vary depending on the viscosity of spray liquids.Therefore,by transforming the viscosity of the spray liquid to adjust the droplet spectrum to reduce drift,increasing the Rm and spreading area to improve liquid utilization and reduce the usage of pesticides.

Motion model for describing the quantity of air in droplets through changing the structure of air induction nozzle

Air induction nozzles possess good anti-drift performance,the throat and orifice sizes of the nozzles are the main design parameters that affecting atomization.Therefore,Venturi tube nozzles and conventional flat fan nozzles were assembled together to investigate the flow rate,droplet size,the quantity of air in droplets affected by a single design parameter of nozzles with applying high speed camera and Spraytec laser diffraction system.The results showed that:the flow rate of the air induction nozzle depended only on the throat size of Venturi tube and pressure,and it was proportional to the throat size of Venturi tube at the same pressure;The flat fan nozzle’s orifice size and Venturi tube size significantly affected volume median diameter of droplets,which generally increased after adding surfactant;A new model was established after optimizing classical equation for calculating the percentage of intake air in droplets and studying the effects of throat and orifice size of air induction nozzles on spray characteristics.By variance analysis,it was verified that the new model of quantity of air in droplets produced by all connected nozzles was correct.The calculation showed that the bubbles sizes ranged at 200-900μm and were in proportion to the droplet size with the percentage of intake air of 10%to 90%.Contrast to the change of volume median diameter and droplet velocity,the existence of intake air could influence their change degree to some extent.