Agronomy

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6 pages, 186 KB

Open AccessEditorial

Advances in Precision Pesticide Spraying Technology and Equipment

by Longlong Li and Chenhui Zhang

Agronomy 2026, 16(9), 903; https://doi.org/10.3390/agronomy16090903 - 30 Apr 2026

Viewed by 486

Abstract

Against the backdrop of increasing global food demand, chemical pesticides remain a key means of controlling biotic stress in modern agricultural plant protection systems [...] Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

Research

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20 pages, 3634 KB

Open AccessArticle

A Monitoring Method for In-Flight Droplet Flow Rate Based on Laser Imaging

by Yue Zhong, Zhonghua Miao, Yanlei Liu, Chuangxin He, Yanlong Zhang, Fan Feng, Wei Zou, Changyuan Zhai and Zhichong Wang

Agronomy 2026, 16(7), 684; https://doi.org/10.3390/agronomy16070684 - 24 Mar 2026

Viewed by 438

Abstract

Efficient plant protection requires precise monitoring of spray droplets, yet current in situ methods for measuring in-flight droplet flow are limited. This study proposed a laser imaging-based method to quantify spray intensity without physical contact or tracers. An optimal imaging angle was determined [...] Read more.

Efficient plant protection requires precise monitoring of spray droplets, yet current in situ methods for measuring in-flight droplet flow are limited. This study proposed a laser imaging-based method to quantify spray intensity without physical contact or tracers. An optimal imaging angle was determined via simulation by maximizing the linearity between the received optical feature and droplet volume density while satisfying geometric constraints. A compact acquisition device was then developed and tested with eight nozzle specifications under fixed pressure. Image processing algorithms—including cropping, RGB channel separation, and binarization—were employed to extract pixel area and cumulative intensity, with gravimetric measurements serving as the reference. Results showed that under optimized exposure and gain settings, features from the green and blue channels exhibited a strong linear correlation with flow rate (R² = 0.93–0.97). Based on these findings, this study demonstrates that in-flight droplet flow rate can be directly quantified from image features—a departure from conventional deposition-based approaches. The proposed method enables rapid, non-contact spray assessment using only a camera and laser module, offering a low-cost, simple-structured solution for spray system optimization and field monitoring. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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19 pages, 9120 KB

Open AccessArticle

Experimental Study on the Airflow Field Distribution Characteristics of a Multi-Outlet Air-Assisted Orchard Sprayer with Variable Inlet Area

by Fan Feng, Yanlong Zhang, Zhichong Wang, Hanjie Dou, Yanlei Liu, Yue Zhong, Changyuan Zhai and Jianjun Hao

Agronomy 2026, 16(4), 450; https://doi.org/10.3390/agronomy16040450 - 14 Feb 2026

Cited by 1 | Viewed by 613

Abstract

Multi-outlet air-assisted sprayers are increasingly used for directional and zoned airflow to match varying canopy structures. In this study, a self-developed multi-outlet orchard air-assisted sprayer was investigated. Airflow velocity and direction were tested at different inlet areas, heights, and downstream horizontal distances using [...] Read more.

Multi-outlet air-assisted sprayers are increasingly used for directional and zoned airflow to match varying canopy structures. In this study, a self-developed multi-outlet orchard air-assisted sprayer was investigated. Airflow velocity and direction were tested at different inlet areas, heights, and downstream horizontal distances using a three-dimensional ultrasonic anemometer. Analysis of variance (ANOVA) and regression modeling were applied to elucidate the effects of these three factors on airflow velocity, horizontal angle (θ), and elevation angle (Φ). The results showed that a stable alternating “primary jet–interaction zone” structure was formed in the spatial airflow field under all operating conditions, indicating that the fundamental airflow pattern was mainly governed by the sprayer layout. Varying the inlet area did not alter the basic airflow structure; however, the intensity and directional stability of the primary jets were significantly modified. Larger inlet openings produced higher airflow velocities, with a maximum near-field velocity of 19.7 m s⁻¹, whereas smaller inlet openings resulted in faster far-field attenuation and more pronounced diffusion. Increasing the inlet area caused the θ distribution peak to converge toward 0°, thereby improving axial coherence and directional stability. In contrast, decreasing the inlet area shifted Φ toward more negative values, with Φ reaching approximately −20° in the far field; moreover, far-field differences in Φ were more pronounced. Under the minimum inlet opening area condition (S1), the airflow velocity within the region 80–100 cm from the outlet can be stably maintained above 3 m/s, with a relatively uniform velocity distribution. This is beneficial for improving droplet deposition uniformity within the canopy and reducing droplet drift in non-target areas. Based on the experimental data, a regression model for mean airflow velocity was established (R² = 0.873), demonstrating good predictive performance and indicating that inlet-opening regulation is feasible. These findings provide a basis for airflow matching and spray-parameter optimization for different canopy structures. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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15 pages, 3507 KB

Open AccessArticle

Online Monitoring of Aerodynamic Characteristics of Fruit Tree Leaves Based on Strain-Gage Sensors

by Yanlei Liu, Zhichong Wang, Xu Dong, Chenchen Gu, Fan Feng, Yue Zhong, Jian Song and Changyuan Zhai

Agronomy 2026, 16(3), 279; https://doi.org/10.3390/agronomy16030279 - 23 Jan 2026

Viewed by 528

Abstract

Orchard wind-assisted spraying technology relies on auxiliary airflow to disturb the canopy and improve droplet deposition uniformity. However, there are few effective means of quantitatively assessing the dynamic response of fruit tree leaves to airflow or the changes in airflow patterns within the [...] Read more.

Orchard wind-assisted spraying technology relies on auxiliary airflow to disturb the canopy and improve droplet deposition uniformity. However, there are few effective means of quantitatively assessing the dynamic response of fruit tree leaves to airflow or the changes in airflow patterns within the canopy in real time. To address this, this study proposed an online monitoring method for the aerodynamic characteristics of fruit tree leaves using strain gauge sensors. The flexible strain gauge was affixed to the midribs of leaves from peach, pear and apple trees. Leaf deformations were captured with high-speed video recording (100 fps) alongside electrical signals in controlled wind fields. Bartlett low-pass filtering and Fourier transform were used to extract frequency-domain features spanning between 0 and 50 Hz. The AdaBoost decision tree model was used to evaluate classification performance across frequency bands. The results demonstrated high accuracy in identifying wind exposure (98%) for pear leaf and classifying the three leaf types (κ = 0.98) within the 4–6 Hz band. A comparison with the frame analysis of high-speed video recordings revealed a time error of 2 s in model predictions. This study confirms that strain gauge sensors combined with machine learning could efficiently monitor fruit tree leaf responses to external airflow in real time. It provides novel insights for optimizing wind-assisted spray parameters, reconstructing internal canopy wind field distributions and achieving precise pesticide application. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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20 pages, 3863 KB

Open AccessArticle

Research on a Multi-Sensor Fusion-Based Method for Fruit-Tree Dripline Path Detection

by Daochu Wei, Zhichong Wang, Jingwei Wang, Xuecheng Li, Wei Zou and Changyuan Zhai

Agronomy 2026, 16(1), 20; https://doi.org/10.3390/agronomy16010020 - 21 Dec 2025

Viewed by 618

Abstract

To enable automatic extraction of high-precision paths for intelligent orchard operations, a path detection method targeting the fruit-tree dripline is proposed. The method integrates 2D-LiDAR, RTK-GNSS, and an electronic compass, achieving time synchronization, coordinate-frame construction, and extrinsic calibration. Point clouds are rotation-normalized via [...] Read more.

To enable automatic extraction of high-precision paths for intelligent orchard operations, a path detection method targeting the fruit-tree dripline is proposed. The method integrates 2D-LiDAR, RTK-GNSS, and an electronic compass, achieving time synchronization, coordinate-frame construction, and extrinsic calibration. Point clouds are rotation-normalized via least-squares trajectory fitting; ground segmentation and statistical filtering suppress noise; segment-wise extremal edge points, together with an α-shape-based concave hull algorithm, fit and generate the dripline path; and inverse rotation restores the result to the orchard-local coordinate frame. Field experiments demonstrated that the method accurately extracts dripline paths in orchard environments; relative to manual measurements, the overall mean absolute error was 0.23 m and the root-mean-square error was 0.30 m. Across different travel speeds, the system exhibited good adaptability and stability, meeting the path-planning requirements of precision orchard operations. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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20 pages, 3020 KB

Open AccessArticle

Orchard Variable-Rate Sprayer Using LiDAR-Based Canopy Volume Measurement

by Chao Zhang, Qiujie Li, Pengcheng Yuan and Hongping Zhou

Agronomy 2025, 15(12), 2709; https://doi.org/10.3390/agronomy15122709 - 25 Nov 2025

Cited by 3 | Viewed by 1268

Abstract

This study developed and evaluated a LiDAR-based variable-rate orchard sprayer to address the inefficiency of traditional constant-rate application. The system dynamically adjusts pesticide output in real-time using a canopy volume calculation model and an adaptive delayed-spray mechanism, synchronized with LiDAR scans and travel [...] Read more.

This study developed and evaluated a LiDAR-based variable-rate orchard sprayer to address the inefficiency of traditional constant-rate application. The system dynamically adjusts pesticide output in real-time using a canopy volume calculation model and an adaptive delayed-spray mechanism, synchronized with LiDAR scans and travel speed. Experimental results demonstrated effective performance: the canopy volume estimation achieved a low overall error of 2.84%, enabling precise spray decision-making. The dosage control system showed an average error of 8.78%, and the adaptive system responded within 160 ms, distinguishing target gaps as small as 75 mm. Deposition tests confirmed uniform coverage within the canopy and minimal drift. The system proves to be a practical solution for significantly reducing pesticide use, operational costs, and environmental impact, marking a substantial advancement in precision orchard management. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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18 pages, 6155 KB

Open AccessArticle

Evaluation of Spray Performance of Swing-Arm Sprayer on Droplet Deposition on Greenhouse Tomatoes

by Zhongyi Yu, Guangfu Wang, Hongtu Zhang, Keyao Zhao, Xiangsen Meng, Jiashu Guo, Mingtian Geng, Tianze Luo, Kekun Zhou and Xiongkui He

Agronomy 2025, 15(9), 2220; https://doi.org/10.3390/agronomy15092220 - 19 Sep 2025

Cited by 3 | Viewed by 1292

Abstract

In view of the problems existing in the application of greenhouse pesticides in China, this paper developed a swing-arm sprayer for greenhouse high-stem crops through field research and a literature review. Static and dynamic simulations of the swing-arm mechanism were carried out to [...] Read more.

In view of the problems existing in the application of greenhouse pesticides in China, this paper developed a swing-arm sprayer for greenhouse high-stem crops through field research and a literature review. Static and dynamic simulations of the swing-arm mechanism were carried out to verify the rationality of the structure. The average contact angle between the water and tomato leaves was 49.39°, while the contact angle of the auxiliary solution on the tomato leaves decreased to 40.98°. An indoor atomization test platform was designed to accurately test the particle size and spray performance. The relative span (RS) of droplet distribution showed that the RS values of nozzles 015, 02, and 03 were relatively small, while the RS value of nozzle 04 was about 1.734. With the addition of additives, the RS value of nozzle 02 decreased from 1.305 to 1.021. The field tests showed that the deposition of fog droplets on the front of tomato leaves was in the order of middle > lower > ground > upper (3.622 μL/cm², 3.005 μL/cm², 2.977 μL/cm², and 2.931 μL/cm², respectively). The results indicate that adding additives or increasing the swing-arm angle is beneficial for improving the uniformity of canopy droplet deposition. The front fog droplet coverage of the lower canopy of tomatoes was the lowest, with an average of 26.00%, while the middle and upper canopies had the highest, with an average of 50.58% and 50.72%, respectively. The research found that the spray coverage rate on the front and back sides of tomato leaves was relatively uniform, indicating that the swing-arm greenhouse sprayer designed in this paper could meet the spray quality requirements for tomato pest control. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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16 pages, 3686 KB

Open AccessArticle

Modeling of Droplet Deposition in Air-Assisted Spraying

by Jian Song, Zhichong Wang, Changyuan Zhai, Chenchen Gu, Kang Zheng, Xuecheng Li, Ronghua Jiang and Ke Xiao

Agronomy 2025, 15(7), 1580; https://doi.org/10.3390/agronomy15071580 - 28 Jun 2025

Cited by 3 | Viewed by 1171

Abstract

Air-assisted spraying is the primary method of plant protection in orchards, and precision spraying according to the canopy characteristics of fruit trees can reduce waste and pollution due to pesticide drift. To facilitate targeted pesticide application in the canopy of fruit trees, this [...] Read more.

Air-assisted spraying is the primary method of plant protection in orchards, and precision spraying according to the canopy characteristics of fruit trees can reduce waste and pollution due to pesticide drift. To facilitate targeted pesticide application in the canopy of fruit trees, this study employed a newly developed wind-speed-adjustable orchard sprayer and established a prediction model for deposition based on data from orthogonal trials using a central composite design accounting for the coupling effect of three-dimensional spatial parameters. The experimental design systematically quantified the interaction effects of spray distance (1.5–2.5 m), fan wind speed (10–20 m/s), and deposition height (0.5–3 m) on the spatial distribution of droplets. Model significance was p < 0.0001 and the misfit term was significant (p = 0.2193), supporting its validity. The research found that wind speed and distance significantly interact in influencing deposition. By adjusting fan speed and spray distance, variable applications can be achieved in different canopy zones during plant protection operations. The response surface model developed in this study can be applied to variable-rate spraying control systems, thus providing a quantitative basis for dynamic droplet control guided by canopy characteristics. Validation tests revealed that the model’s accuracy was lower in high canopy regions and upwind spraying scenarios, indicating areas for further research. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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21 pages, 14098 KB

Open AccessArticle

Characteristics of the Liquid Sheet of Air-Induction Spray

by Mingzhi Yan, Fujun Chen, Chen Gong and Can Kang

Agronomy 2025, 15(6), 1270; https://doi.org/10.3390/agronomy15061270 - 22 May 2025

Cited by 2 | Viewed by 1211

Abstract

Spraying remains the primary method of pesticide application in plant protection, and spray drift is one of the important reasons that cause pesticide loss and environmental pollution. Air-induction spray is an anti-drift technology based on the Venturi effect. Unlike standard flat-fan sprays, the [...] Read more.

Spraying remains the primary method of pesticide application in plant protection, and spray drift is one of the important reasons that cause pesticide loss and environmental pollution. Air-induction spray is an anti-drift technology based on the Venturi effect. Unlike standard flat-fan sprays, the atomization mechanism of air-induction sprays has not yet been thoroughly studied. Therefore, a deep understanding of atomization and disintegration characteristics of air-induction spray liquid sheets is very important. This study utilized high-speed camera imaging technology to visualize the liquid sheet of air-induction sprays. Quantitative measurements were conducted on the disintegration length, spray angle, and bubble size of the liquid sheets. A comparative analysis was performed to examine the differences in liquid sheet structures between air-induction sprays and standard flat-fan sprays. The effects of different nozzle configurations and spray pressures on the liquid sheet of air-induction sprays were also discussed. The results indicate that bubbles are typical structures of the liquid sheets of the air-induction spray, and their disintegration can lead to perforations or interfacial disturbances in the liquid sheet. The study observed the coalescence of double or multiple bubbles within the liquid sheet, with atomized droplets potentially containing single or multiple bubbles. Compared to standard flat-fan sprays, air-induction sprays have smaller liquid sheet spray angles and disintegration lengths, by 23.48% and 16.32%, respectively. Bubble size decreases with increasing spray pressure but increases with larger nozzle orifice sizes. The spray angle of the liquid sheet significantly increases with higher spray pressures and larger nozzle orifice sizes. Meanwhile, the disintegration length of the liquid sheet shows a slight increase with rising spray pressures and larger nozzle orifice sizes. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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18 pages, 7370 KB

Open AccessArticle

The Effect of Pesticide Solutions on the Deposition of Bubble-Containing Droplets

by Mingzhi Yan, Feng Jia, Chen Gong and Can Kang

Agronomy 2025, 15(5), 1172; https://doi.org/10.3390/agronomy15051172 - 12 May 2025

Cited by 3 | Viewed by 1405

Abstract

The deposition of spray droplets is a critical topic in plant protection. The air-induction nozzle is believed to mitigate spray drift by producing bubble-containing droplets. However, research on the deposition of bubble-containing droplets is limited. In this study, the deposition process of bubble-containing [...] Read more.

The deposition of spray droplets is a critical topic in plant protection. The air-induction nozzle is believed to mitigate spray drift by producing bubble-containing droplets. However, research on the deposition of bubble-containing droplets is limited. In this study, the deposition process of bubble-containing droplets was investigated using high-speed photomicrography. Three typical pesticide solutions, oil-based emulsions, suspensions, and aqueous solutions were used to produce bubble-containing droplets. Both hydrophilic and hydrophobic surfaces were used as deposition targets. The results indicate that the deposition of bubble-containing droplets can generate a central jet resembling the Worthington jet. All three solutions reduced liquid surface tension, thereby increasing the maximum spreading diameter of bubble-containing droplets. On hydrophilic surfaces, a functional curve describing the maximum spreading factor was fitted based on the dimensionless Weber number (We), expressed as

f_{\max} = 0.04 {We}^{0.508} + 3.21

. On hydrophobic leaves, the dynamic evolution and retention effects of bubble-containing droplets were analyzed. Suspensions and aqueous solutions exhibited droplet rebound, while oil-based emulsions transitioned from rebound (0–0.2% concentration) to adhesion (0.4–0.8% concentration), with 0.4% identified as the critical concentration for this rebound-to-adhesion transition. Morphological variations during deposition, including rebound, splashing, and fragmentation, were also observed across different solution concentrations. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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24 pages, 15025 KB

Open AccessArticle

Drift Suppression by Adjusting Flight Parameters for Manned Helicopters in Forested Regions

by Shuping Fang, Liping Chen, Yu Ru, Ningning Wang, Xiaojun Jin, Yangyang Liu and Lingyuan Sun

Agronomy 2025, 15(5), 1129; https://doi.org/10.3390/agronomy15051129 - 4 May 2025

Cited by 2 | Viewed by 1209

Abstract

Under complex climatic conditions, variable application parameters and a two-dimensional application route, it is difficult to ensure the accurate deposition of pesticide droplets during helicopter aerial applications. This is especially true when the deposition area is forested. The Agricultural Dispersal (AGDISP) model was [...] Read more.

Under complex climatic conditions, variable application parameters and a two-dimensional application route, it is difficult to ensure the accurate deposition of pesticide droplets during helicopter aerial applications. This is especially true when the deposition area is forested. The Agricultural Dispersal (AGDISP) model was used with an optimization procedure to study the influence of flight height, flight speed, and ambient wind speed. Optimization techniques were used to obtain the best fit between the simulation results. Three objectives were used to propose a new application strategy, namely (i) the average deposition in the forest area; (ii) the uniformity of droplet deposition; and (iii) the deposition at a distance of 50 m downwind outside the forest area. A new application strategy was proposed, where the forest area was divided into two subareas, namely the safe area (the area away from forest boundaries) and the edge area (the area close to forest boundaries). Flight height and speed were adjusted to ensure the desired average deposition and uniformity in the safety area and the desired deposition at 50 m downwind in the edge area. Six helicopter spraying experiments at different wind speeds were conducted at Longtan, Nanjing, China. The deposition effects of the new strategy were compared with those of the common manual empirical method (operating at the same height and speed over the whole forest). It was found that at wind speeds of 2 m/s, 1 m/s, and 2.5 m/s, the average deposition in the safe area was improved by 4.82%, 0.91%, and 8.24%, respectively, and that in the edge area, it was improved by 7.04%, 0.90%, and 0.77%, respectively. Conversely, the deposition at 50 m downwind was reduced by 25.00%, 16.58% and 22.90%, respectively. These experimental results demonstrated that the new strategy can effectively reduce the droplet drift. We achieved the synergistic optimization goal of moderate (and uniform) deposition in the forest area with low deposition outside the forest area. This study can provide important technical references for precision forestry. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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16 pages, 10141 KB

Open AccessArticle

The Effect of Pesticide Formulation on the Characteristics of Air-Induction Sprays

by Mingzhi Yan, Fujun Chen, Chen Gong and Can Kang

Agronomy 2025, 15(4), 979; https://doi.org/10.3390/agronomy15040979 - 18 Apr 2025

Viewed by 1264

Abstract

Air-induction sprays are widely used for drift control; however, their disintegration mechanism is not yet fully understood. After exiting the nozzle, the liquid typically first forms a liquid sheet, which then breaks up into droplets. Therefore, a deep understanding of the liquid sheet [...] Read more.

Air-induction sprays are widely used for drift control; however, their disintegration mechanism is not yet fully understood. After exiting the nozzle, the liquid typically first forms a liquid sheet, which then breaks up into droplets. Therefore, a deep understanding of the liquid sheet of air-induction sprays is essential for elucidating its disintegration mechanism. In this study, high-speed photography and image processing methods were employed to capture and measure the structure of the liquid sheet of air-induction sprays under different pesticide formulations. The effects of different pesticide formulations on the liquid sheet’s spreading angle, breakup length, and the behavior of bubbles within the liquid sheet were analyzed. The results indicate that compared to pure water, pesticide solutions significantly alter the liquid sheet’s spreading angle, length, and bubble size. Under oil-based emulsion conditions, the sheet length and bubble size decrease with increasing concentration, while the spreading angle is less affected. The oil phase in emulsions exhibits defoaming properties, reducing the number of large bubbles. Additionally, oil droplets contribute to the formation of perforations in the liquid sheet, leading to earlier breakup and shortening the sheet length. For suspensions, the variation in liquid sheet behavior is similar to that observed in oil-based emulsions, but its effect on bubble size is less pronounced. In aqueous solutions, bubble size decreases with increasing concentration, but the number of bubbles significantly increases. Moreover, the liquid sheet length and spreading angle increase markedly with concentration. Unlike oil-based emulsions and suspensions, which contain hydrophobic dispersed phases, aqueous solutions do not exhibit significant defoaming properties. Our work can provide a theoretical reference for the applications of air-induction sprays. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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20 pages, 19733 KB

Open AccessArticle

Experimental Research on the Atomization Characteristics of Air-Induction Spray Based on Oil-Based Emulsion

by Mingzhi Yan, Fujun Chen, Chen Gong and Can Kang

Agronomy 2025, 15(4), 936; https://doi.org/10.3390/agronomy15040936 - 11 Apr 2025

Viewed by 1425

Abstract

Spray drift is one of the major factors that causes pesticide loss and environmental pollution. Air-induction spray is an important anti-drift technology; however, the atomization characteristics of air-induction spray, particularly when the spray liquid is an oil-based emulsion, are not yet fully understood. [...] Read more.

Spray drift is one of the major factors that causes pesticide loss and environmental pollution. Air-induction spray is an important anti-drift technology; however, the atomization characteristics of air-induction spray, particularly when the spray liquid is an oil-based emulsion, are not yet fully understood. In this paper, high-speed photography, PIV (particle image velocimetry) and image processing techniques are used to study the atomization characteristics of the air-induction spray under the oil-based emulsion condition. The structure of liquid sheet, the spatial distributions of the spray droplets size and the velocity are captured and measured. Additionally, the effects of spray pressure and nozzle configuration on atomization characteristics are discussed. The results indicate that, compared to water, air-induction spray under oil-based emulsion conditions exhibits a larger spray angle, a smaller droplet size, a narrower droplet size distribution and a higher droplet velocity. It is indicated that the oil-based emulsion reduces the size of bubbles within the liquid sheet, thereby decreasing the size of bubble-containing droplets. Furthermore, the oil-based emulsion alters the breakup mode of the liquid sheet, leading to an increase in droplet velocity and a narrower droplet size distribution. Both spray pressure and nozzle configuration have significant effect on the atomization characteristics. When the spray pressure changes from 0.1 MPa to 0.3 MPa and 0.5 MPa, the droplet size decreases by 10.56% and 15.67%, respectively, while the droplet velocity increases by 46.12% and 91.06%, respectively. When the nozzle changes from ID120-01 to ID120-03 and ID120-05, the droplet size increases by 20.64% and 33.99%, respectively, while the droplet velocity increases by 3.71% and 14.15%, respectively. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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Review

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26 pages, 1718 KB

Open AccessReview

Research Progress on Intelligent Variable-Rate Spray Technology for Precision Agriculture

by Yuxuan Jiao, Songchao Zhang, Yongkui Jin, Longfei Cui, Chun Chang, Suming Ding, Zhu Sun and Xinyu Xue

Agronomy 2025, 15(6), 1431; https://doi.org/10.3390/agronomy15061431 - 11 Jun 2025

Cited by 13 | Viewed by 8437

Abstract

Conventional continuous pesticide application remains prevalent in agriculture, but its limitations in addressing the spatial–temporal variability of biotic stressors have led to excessive chemical inputs and inefficiency. The emergence of precision agriculture has catalyzed significant advancements in variable-rate spray systems to optimize agrochemical [...] Read more.

Conventional continuous pesticide application remains prevalent in agriculture, but its limitations in addressing the spatial–temporal variability of biotic stressors have led to excessive chemical inputs and inefficiency. The emergence of precision agriculture has catalyzed significant advancements in variable-rate spray systems to optimize agrochemical deployment through real-time modulation. This technology demonstrates critical advantages in minimizing the environmental footprint while maintaining crop protection efficacy. Our systematic review analyzes three foundational variable-rate spray architectures—pressure-regulated, flow rate-regulated, and pesticide concentration-regulated mechanisms—evaluating their maturity and implementation paradigms. Pressure-regulated technology relies on the pressure–flow relationship to achieve regulation, but there is a narrow range in flow regulation, atomization stability is insufficient, and there are other defects. Flow rate-regulated technology achieves precise control through the dynamic adjustment of the nozzle orifice area or Pulse-Width Modulation duty cycles, but this technology faces mechanical wear, a nonlinear flow–duty cycle relationship, and other challenges. Pesticide concentration-regulated technology is centered on real-time mixing, which can avoid the residue of chemicals but is highly dependent on fluid characteristics and mixing efficiency. This study proposes improvement paths from the perspectives of hardware optimization, control strategy integration, and material innovation. Through the summary and analysis of this paper, we hope to provide valuable references for future research on variable-rate spray technology. Full article

(This article belongs to the Special Issue Advances in Precision Pesticide Spraying Technology and Equipment)

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