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Article

Influence of Air-Jet Configuration on Spray Deposit and Drift in a Blackcurrant Plantation

The National Institute of Horticultural Research, Konstytucji 3 Maja 1/3, 96-100 Skierniewice, Poland
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(10), 2360; https://doi.org/10.3390/agronomy15102360
Submission received: 28 August 2025 / Revised: 25 September 2025 / Accepted: 29 September 2025 / Published: 9 October 2025
(This article belongs to the Section Agricultural Biosystem and Biological Engineering)

Abstract

The subject of the research was a prototype two-row sprayer, equipped with a centrifugal fan and directed air-jet emission system, dedicated to the chemical protection of berry plantations, and, in particular, blackcurrants. The prototype was set up with two configurations: “offset”, in which the opposing air streams were “offset” by 0.5 m, and “face-to-face”, when they were positioned opposite each other. The field experiments were carried out on a blackcurrant plantation (Tisel cv.; bush spacing of 4.0 × 0.5 m; height 1.2 m; width 2.5 m). The spray deposition within the crop canopies as well as spray drift to the air and to the ground were assessed using the fluorescence method in order to compare the quality of treatments performed with the two-row sprayer and a conventional axial fan sprayer with radial air discharge system. Spray applications were performed at spray volume 300 L∙ha−1 and working speed 6 km h−1 by both sprayers. The plantation was sprayed with 0.25% water solution of a fluorescent tracer BF7G. The in-canopy spray deposit and spray drift were evaluated using artificial targets made of filter paper. Although directed air-jet sprayer in two configurations (“offset” and “face-to-face”) and conventional one produced similar deposits within the bushes, the spray loss from the directed air-jet sprayer was considerably lower (25.1–32.2%) than that from the conventional sprayer (76.9–81.8%) generating considerably greater airflow volume. Lower PPP losses mean lower environmental impact, which is in line with integrated plant protection. The research responds to numerous inquiries from sprayer manufacturers and blackcurrant growers regarding the most appropriate configuration of the air flow outlet planes. The results obtained will contribute to increasing the efficiency of spraying and facilitate the implementation of the European Green Deal and the achievement of the target of a 50% reduction in the use of plant protection products after 2030 in the EU.

1. Introduction

The European Farm to Fork Strategy, which is at the heart of the European Green Deal, aims to make food systems environmentally friendly so as to reduce the risks associated with pesticides [1,2]. It is expected that the risk associated with using PPP will be reduced by 50% by the year 2030, with the goal of implementing these plans and taking additional measures to halve the use of chemical pesticides by this time. This extremely ambitious plan, in such a short time, seems to be a very challenging task, given the technologies currently used in fruit production, as well as in spraying techniques. Therefore, widespread and integrated actions should be taken, with particular focus on minimizing the use of pesticides and reducing their emissions to the environment during spray application.
Poland is the world leader in production of berry fruit such as blackcurrants, gooseberry or chokeberry. Although fruit production of this type is fully mechanized, further opportunities to reduce production costs are being sought. Despite the fact that the number of chemical treatments in blackcurrant plantations is almost three times lower than in orchards, the percentage of the chemical protection cost is still higher due to the lower market price. In existing berry fruit plantations, standard orchard sprayers equipped with axial fans and radial air-jet emission still dominate. However, it has been determined that the spray discharge system should be adjusted with the canopy profile [3]. Therefore, this type of sprayer, originally designed for use on trees, is not suitable for currant bushes, due to the imprecise air stream caused by the excessive height of the fan impeller axis. These sprayers, therefore, require high spray volumes (600–800 L ha−1) in order to guarantee satisfactory pest and disease control, which in turn, results in relatively high spray loss, thus considerably contributing to environmental pollution. It has also been demonstrated, that a reduction in spray volumes from 600 to 260 L∙ha−1 whilst maintaining satisfactory control of spider mites (Tetranychus urticae Koch) and currant rust (Cronartium ribicola J. C. Fisher) on blackcurrants was possible using a directed air-jet sprayer [4]. Tree Row Volume (TRV) formula confirms the possibility of reducing spray volume on currant plantations to 300 L/ha. Although developed for orchards, it is so versatile that it can also be used to determine spray volume rates for fruit bushes, such as blackcurrants [4].
Spray application in fruit growing is a very complex process which requires uniform pesticide distribution whilst maintaining minimal spray loss, caused by spray drift, which is the main source of environmental pollution. Spray drift is defined as the quantity of PPP that is carried out of the treated area by the action of air currents during the application process [5]. Among the many factors influencing the amount of drift produced during the treatment, the spray application techniques (e.g., parameters and configuration of air-jet discharge system, droplet size, travel speed) are considered the most important. Parts of the drifted droplet are carried outside the spray area under the influence of air currents during spray application, whilst other particles could be deposited on the ground, directly in the tractor path as well as in the adjacent bush rows.
During spray applications on blackcurrant plantations, the spray drift to the soil was not affected by the air-jet discharge system, while the spray drift to the air, recorded on the frame behind the bushes, was 20 times higher from a conventional axial fan sprayer than from a directed air-jet sprayer [4]. Thus, precise, target-oriented application techniques have a considerable environmental advantage compared to conventional ones.
The sprayer’s configuration and its parameters are also a subject for discussion. Due to the limited availability of research results for blackcurrant, chokeberry and gooseberry, an analysis of the available literature in the field of vine-spraying techniques was also carried out, as they are similar in terms of general principles and difficulties; in particular, the need to reduce spray drift in order to decrease the environmental risks and PPP losses, as well as the spray deposit and its uniformity [6,7,8,9]. Earlier studies have shown that the concept of using wide-fan outlet ducts has been employed for at least 40 years as a tool for improving spray penetration into fruit crops when using conventional axial fans. Other studies and theoretical considerations also support this idea, but only for rigid trees or low-density crop structures [10]. The author also suggests a possible exception to the rule that increasing the jet width always improves crop penetration, as a narrow air-jet may be more effective at forcing openings in the outer leaves of a dense crop. This belief is also confirmed by other authors [4], who found that a conventional air-jet discharge system equipped with an axial fan and wide outlet ducts resulted in over 55% less spray deposition in the inner part of the bush, than that obtained with the directed air-jet system with a narrow air-jets. For this reason, as well as due to the reduced spray drift, the authors recommend this emission system as the most suitable for spray applications on commercial blackcurrant plantations.
Previous studies have shown, that increasing the operating speed above 6 km∙h−1 increases the PPP losses [4]. Although, it was possible to obtain a satisfactory quality of blackcurrant treatments with the use of a tunnel sprayer even at the speed 10 km∙h−1, the wide use of such machines seems to be questionable due their high cost. With this in mind, one of the possibilities of increasing the treatment capacity is to enlarge the swath width of the equipment, by introducing two-row or multi-row sprayers. These kind of machines were developed for vineyards, which inspired the designers to develop a similar sprayer for berry fruit plantations. They are usually equipped with a centrifugal fan and a directed air-jet emission system with pneumatic nozzles. However, due to limitations of pneumatic nozzles compared to hydraulic ones [11,12] and different canopy characteristics of bushes, slightly different spatial configurations are necessary.
The air-assisted sprayers generate airflow that is to open the canopy of the 3D target crop and convey the spray into the canopy in order to distribute the applied product as evenly as possible. It must be carefully adjusted to ensure satisfactory spray deposition on the target with minimum product loss which results in environmental contamination. In this context, the appropriate reduction in pesticide emissions towards the sprayed crop is the basis for proper pest control [13,14,15]. During spraying, some of the spray liquid that is not deposited on the target is lost as drift [16]). This loss can reduce the efficacy of the treatment, while also contributing to environmental pollution [17,18]. Therefore, spray drift reduction by optimized air flow adjustment is a major issue in the design and the use of air-assisted sprayers [8,19,20].
To optimize an air emission system, its range and output must be determined by using appropriate measurement equipment. Simple cup anemometers and Pitot tubes do not guarantee the expected measurement accuracy. Precision hot-wire anemometers are used to measure airflow through a unidirectional duct and their use for measuring air velocity and direction in open spaces is limited [15]). Ultrasonic anemometers are best suited for measuring airflows generated by sprayer fans as they provide the value of each of the three air velocity components, also enabling the determination of its direction [21,22].
Currant bushes (2.5 × 1.3 m—width × height) are usually lower than vines (0.7 × 2.0 m—width × height), but they are much wider and more dense (Figure 1), which makes it difficult to evenly distribute the PPP throughout the whole bush volume. The first two-row sprayers dedicated to blackcurrant spraying were also built in Poland. They were usually equipped with an arrangement of 4 oppositely directed air outlets located in one plane, hereinafter referred to as “face-to-face” air-jet discharge system. Whilst this configuration of the emission system favors turbulence created during the interaction of air streams and increases the spray coverage of the bushes, it was also observed that access of droplets to the interior of the bush was impeded. In an attempt to overcome this problem an experimental two-row sprayer was built in which opposite air outlets can be mounted in the same vertical plane or in two mutually “offset” planes, so as to allow the free penetration of the bushes by the spray droplets.
Very efficient are measurement with the use the artificial targets (filter papers) and mineral chelate tracer (B, Co, Cu, Fe, Mn, Mo, Zn) which allowed the use of the same samplers for multiple treatments [23,24,25]. In the presented studies, a more precise method was used, consisting in a quantitative method using fluorescent tracer. Because of relatively easy and inexpensive procedure, the fluorescent tracer dyes have been widely used for spray deposit assessment from agricultural sprayers [26]. Therefore, the fluorescent tracers are often used for spray deposition and drift measurements because of their high sensitivity, allowing them to measure very low spray deposits [27,28].
There is a lack of literature on currant-spraying techniques, and research in this field should be continued because the specific spatial structure prevents the use of available results concerning, for example, grapevines.
The objective of the presented research was to evaluate the influence of the air-jet system configuration in a two-row directed air-jet sprayer on spray deposit and spray drift in blackcurrant plantations, and to compare the results with those obtained with a conventional axial fan sprayer. This research addresses numerous inquiries from sprayer manufacturers and blackcurrant growers regarding the most appropriate configuration of airflow outlet planes to optimize application uniformity and reduce PPP losses. The experiment was conducted at National Institute of Horticultural Research (InHort) in Skierniewice (Poland).

2. Materials and Methods

2.1. Experimental Two-Row Directed Air-Jet Sprayer

The prototype sprayer used in the study was designed and built at InHort in cooperation with the company Agrola (PHU Agrola, Platkownica, Poland). The sprayer with a precise and target-oriented air-jet discharge system was configured to spray two rows simultaneously. It was equipped with a centrifugal fan that fed four pneumatic pipes, two for each row of bushes, with each having 4 air spouts (Figure 1a). The upper- and lowermost air spouts were adjustable to allow setting of the air-jet direction according to the size and shape of currant bushes, in order to ensure precise spray application (Figure 2a). Each air spout was equipped with one 02 hydraulic nozzle (Figure 1b). The lowest air spouts were mounted 0.3 m above the ground level in order to ensure proper penetration of the bottom part of the bush canopies. The angle of the boom arms, on which the air stream outlets were assembled, could be hydraulically controlled during the treatment to allow the most appropriate adjustment of the air spouts spacing to the width of the bush rows. The prototype was specially adapted for the experiment so that it was possible to configure the spraying plane of the air spouts at two settings, “face-to-face” and at the 0.5 m “offset” position (Figure 2b), so as not to disturb the air flow through the bush.
The 0.5 m displacement in the air-stream planes resulted from spatial measurements of airflow distribution using sonic anemometers. It was expected that the “offset” position would increase the air velocity and enable better penetration of the spray liquid, which would contribute to the increased PPP deposition and decrease the spray drift. Finally, the lower spray loss was expected, which would allow the reduction in the applied PPP and environmental pollution.

2.2. Conventional Axial Fan Sprayer

The conventional sprayer with an axial fan and radial air-jet emission system (Art. 35, ZHP Agrola, Platkownica, Poland) (Figure 3) used in this study is widely used for pesticide application on berry plantations in Poland. The mean air velocity and airflow rate produced by this emission system are shown in Table 1. The values were calculated by multiplying the cross-sectional area of the air outlet (m2), and the average air speed (m∙s−1) measured at different points of the air outlet. Unlike the directed air-jet emission system, all nozzles were mounted in a fixed position. The lowest nozzles were placed at a height of 0.5 m above ground level, and the remaining nozzles were mounted symmetrically in the fan’s outlet slot.

2.3. Air Velocity Measurements

The precise application of sprays in bush crops requests the adjustment not only of spray dose, but also air-jet velocity and air direction according to crop morphology and meteorological conditions. Although air-assisted sprayers have been used in fruit cultivation for many years, they are not adapted to the characteristics of the sprayed bushes. Therefore, before starting the field tests on spray deposit and drift, air flow distribution measurements were taken for both the two-row sprayer and the reference sprayer with an axial fan and a radial air-flow emission.
Air velocity measurements were carried out both in static and dynamic conditions. The static measurements were made at three distances from the air outlets: 0.1, 0.5 and 1.0 m, and repeated 5 times for each distance employing a set of 6 hot-film thermal anemometers (TSI Inc., Shoreview, MN, USA) connected to a high-speed data logger (AAC-2, Intab, Stenkullen, Sweden). The six anemometer probes were spaced every 0.3 m on the vertical mast, which was mounted on the rail track. The total air flow rate produced by the air-jet systems was calculated based on the average of the five air velocity measurements at the air outlet and its surface area. In order to characterize the air-jet parameters of the two-row sprayer, the air velocity distribution was measured at travel speed 6.0 km∙h−1, because previous studies showed that the higher speed increased the spray losses [4]. The cross-section air-velocity profile was measured for the same parameters as during the orchard treatments with the use of the set of 5-th 3-D ultrasonic anemometers Gill WindMaster, model 1590-PK-020/w (Gill Instruments Ltd., Lymington, UK).

2.4. Field Experiment

Atmospheric conditions (wind speed and direction, temperature, and humidity) during field trials are variable, making it difficult to achieve repeatable test conditions. Therefore, attempts have been made to conduct such trials indoors and using artificial plants to circumvent the negative impact of these factors [29]. Despite these advantages, the properties of artificial tree shoots were found to differ from those of natural ones [30]. Therefore, field trials were conducted in a commercial currant plantation.
The field experiments were carried out in Dąbrowice, central Poland (N 51.9158°, E 20.1124°), on the plantation of blackcurrants cv Tisel, with a bush spacing of 4.0 × 0.5 m, bush height 1.2 m and bush width 2.5 m. Spray deposit in bush canopies and spray drift obtained by the two-row directed air-jet sprayer and the conventional axial fan sprayer were compared.
Applications were performed at the recommended and commonly used in practice spray volume 300 L ha−1 [31] and two air volumes characteristic for both sprayers. In addition, two configurations of the spraying planes formed by the air spouts, “face-to-face” and at “offset” position, were also compared. The bushes were sprayed from both sides with the use of hollow cone nozzles T0R 80-02 (Lechler, Metzingen, Germany). The working parameters of the sprayers for all the treatments are given in Table 1.

2.5. Laboratory Measurements

The spray liquid was a 0.25% water solution of a fluorescent tracer BF7G—Acid brilliant flavine 7G (Waldeck Gmbh & Co. KG Havixbecker Str. 62, 48161 Münster, Germany). This tracer is characterized by high photostability, easily dissolves in water and is easily washed from the surface of leaves and artificial targets. The in-canopy spray deposits were collected on artificial targets (2.0 × 4.0 cm) made of filter paper, which were attached on the upper and lower surfaces of 7 leaves located in five bushes (replication) (Figure 4). The spray drift to the air and on the ground were determined with the use of the same artificial paper collectors (2.0 × 4.0 cm). The samples for the spray drift evaluation were attached at eight levels on the vertical frame and on the ground in four lines considered as replicates. The frame was located on the downwind side of the row just in front of the adjacent row. The in-canopy spray deposit and off-target loss were evaluated on both sides of the treated bushes. Wind velocity and its direction, as well as temperature and air humidity, were recorded during the field trials.
After performing the spray applications, samples were collected and secured in plastic snap-seal containers and stored in dark conditions for further processing. The fluorescent dye was extracted from each collector with 40 mL of deionized water. After shaking for 15 min, a concentration of fluorescent dye was measured with the use of fluorescence spectrometer PerkinElmer LS 55 (Perkin Elmer Instruments, Beaconsfield, UK). The data were then converted in order to express the obtained results of tracer deposit in ng cm2 and the spray drift as a percentage of the applied dose.

2.6. Statistical Analysis

The obtained data were analyzed using a multi-way analysis of variance (ANOVA) to determine the effect of the air-jet emission system and air volume on spray deposit on the blackberry leaves and spray drift to the air and to the ground. All statistical analyses were performed using STATISTICA 13. The treatment means were separated by a Duncan’s Multiple Range Test at the significance level p < 0.05. The means are presented as bar graphs with a confidence interval of 95%.

3. Results and Discussion

3.1. Air Distribution Measurements—Indoor Tests

As expected, tests showed a 2-times-higher air flow velocity generated by the centrifugal fan of the two-row sprayer than for the reference sprayer equipped with an axial fan (Table 1). The precise application of sprays in bush crops requests the adjustment not only of spray dose, but also air-jet velocity and air direction according to crop morphology and meteorological conditions. Although air-assisted sprayers have been used in fruit cultivation for many years, they are not adapted to the characteristics of the sprayed bushes. Therefore, before starting the field tests on spray deposit and drift, air flow distribution measurements were taken for both the two-row sprayer and the reference sprayer with an axial fan and a radial air-flow emission (Figure 5).
The axial fans are the most commonly used type in air-assisted bush crop sprayers, because they have a simple and durable construction and are not too expensive to buy. It was reported that there was also three times higher air volume produced by the axial fan compared to the centrifugal one, at the similar power consumption [21,32]. However, they do not have sufficient technical capabilities to precisely regulate air distribution within the bush canopies. Moreover, axial fans are not suitable for building a double-row air emission system, because of the excessive air volume loss. Multi-outlet centrifugal fans are much better suited for this task, because flexible ducts better tolerate both splitting the air flow into two separate rows, as well as directing the air to the desired locations of the bushes with much smaller losses in air output [33]. This belief is confirmed by the results of air-velocity measurements carried out during indoor tests, that indicate an excess of air stream directed to the tops of the bushes (Figure 5; position 1 and 2) and its deficiency in the lower zones at the base of the bushes (Figure 5; position 6) for both lower and higher fan output (1st and 2nd gear). Finally, excessive air volume is directed above the rows of bushes and did not reach the sprayed objects but was transferred above the target zone, becoming the cause of pesticide drift, as well as a source of economic losses and environmental pollution.
The range of air flow produced by radial fans can be easily adjusted to the dimension of the bushes, thanks to the wider possibility of precise adjusting the air-jet direction. They allow more air to be directed towards the base of the bushes just above the ground surface (0.1 ÷ 0.2 m). Therefore, a more even distribution of the spray liquid can be expected, bearing in mind that the lowest shoots of currant bushes are already spread on the ground surface, while for a conventional sprayer the air could be directed to the bushes at a height of no less than 0.3 ÷ 0.5 m. At the same time, the air flow direction for centrifugal fans can be better adapted to the height of the bushes to minimize the drift effect [7,15,20].
Many doubts among users of two-row sprayers equipped with a directed air-jet system were caused by the “face-to-face” arrangement of opposite outlet throats in one plane, that such a configuration reduced the depth of penetration of the bush by the air stream, which threatens the uniformity of application of the spray liquid. This belief is confirmed by measurements made using three-axis ultrasonic anemometers. On the other hand, the opposing “face-to-face” air flow generates air turbulence, which can promote a more even distribution of droplets, especially in the center of the bush, where droplet access is usually difficult. To date, it has not been possible to clarify these doubts through research. Therefore, the air flow plane was moved from the “face-to-face” to the “offset” position by 0.5 m, which resulted in an increase in the range of opposite jets in the bushes by 50% (Figure 6B). It can be expected that the turbulence effect may be reduced. In order to clarify these doubts, field tests of spray liquid deposition and drift were performed for these two air flow configurations.

3.2. Spray Deposit

The range of wind speed during the field experiments was 2.0–3.2 m∙s−1, and it was directed perpendicular to the row’s lines. The range of air temperature was 23–27 °C, with air humidity 58–62%. The tests were carried out at a constant operating speed (6.0 km∙h−1). The plots were randomly distributed, and data in comparable populations were normally distributed and were not transformed. The mean spray deposition values in the canopy during blackcurrant plantation treatments are given in Table 2 and Figure 7 and Figure 8. They indicate the influence of leaf location on the spray deposit which determines the uniformity of its distribution and, as a result, the biological effectiveness of the treatment. The smallest deposits were found on leaves located in the axis of the bushes, close to their base (Figure 4a, position 2 and 3) for all tested combinations [4,19]. However, the average spray deposit shows the spatial distribution of the spray liquid on the plant, so spray deposition measured separately on both the upper and lower leaf surfaces seems to be a more reliable method. Therefore, to evaluate the tested spraying techniques in this experiment, spray deposition was also measured separately on both the upper and lower leaf surfaces. Although the measurements carried out showed clearly greater deposition on the upper surface of the leaves for all the tested spraying techniques, none of them turned out to be statistically significant (Figure 9).

3.3. Spray Drift

Although the spray deposition measurements did not show statistically significant differences between the three tested air-jet discharge systems, such differences were found when spray liquid losses were evaluated. For this purpose, a vertical openwork catching frame was placed on the leeward side of the sprayed plantation and on the ground, to which 4 vertical rows of filter paper samplers were attached at 8 levels, spaced 0.5 m apart, and identical samplers were placed on the ground surface (Figure 4). Airborne drift was measured using vertically placed samplers, while horizontal samplers placed at ground level were used to evaluate sediment drift. The tests performed showed that air airborne drift for the conventional sprayer was four times greater than for the “offset configuration” directed air-jet system and as much as five times greater than for the “face-to-face” system (Table 3, Figure 10) [19]. Whilst there was no significant impact of air output on the amount of this drift, the distribution of the lost liquid captured on the samplers attached to a vertical openwork frame, located on the leeward side of the sprayed row of bushes, was clearly different. Statistically higher drift was found for the conventional air-jet emission system at both air volumes (Figure 11). However, the differences which occurred were not statistically significant in the lower part of the frame (0 ÷ 2 m) at levels 2 and 3. The “face-to face” and “offset” emissions were characterized by much smaller drift, especially in the upper part of the frame (2 ÷ 4 m), which can be explained by having control over the adjustment of the air flow, which enabled the possibility of avoiding heavy drift of spray liquid directed over the bushes. These losses, in the case of the radial air-jet emission were about 3 times smaller in the lower part of the frame (0 ÷ 2 m), than the other two emission systems and as much as 8 ÷ 12 times smaller on samples positioned in the upper part of the frame (position: 5 and 6).
In the lower half of the frame (0 ÷ 2 m), the losses generated by the radial air-jet emission system, were slightly lower than in the upper part (2 ÷ 4 m), which can be explained by the minimal obstruction of movement and retention of droplets by the row of shrubs, bearing in mind, that the height of the bushes was only around 1.5 m. Tests have shown, that increasing air output does not affect the amount of spray losses measured on the vertical frame for sprayers equipped with “offset” and “face-to face” air-jet emission systems (Table 4; Figure 11 and Figure 12). However, such an influence was clear, especially in the upper part of the vertical frame (pos. 4–8), for the conventional sprayer equipped with a radial emission system. Losses of spray liquid applied at ground level at individual measuring points for various factors were also tested, and although they varied greatly, they did not show statistically significant differences. Only at point 1 (Figure 12), located under the vertical frame, drift was significantly higher for the sprayer with radial air flow emission and “face-to-face” spray plane position. This can be explained by the lowest located air outlet, which ensures greater application of spray in a place located at the base of the bush, that is difficult to access for the spray liquid [8,24].
The obtained results were used to determine the percentage of the spray liquid lost during the treatments for the tested spraying techniques in the applied volume rate. (Figure 13). Assuming that the sprayer’s working liquid output is 100%, the highest drift was recorded in the radial emission system, which was 76.9 and 81.8% for the lower and higher air output, respectively. Significantly lower drift was produced for the “offset” (25.1 and 32.2%) and “face-to-face” emission systems (35.2 and 28.8%) of the two-row sprayer. Drift is one of the main causes of environmental pollution and therefore is of great concern to local communities, especially those living in areas adjacent to fruit crop plantations. In addition, it should be considered a loss of pesticides being of economical concern of the applicator.
The fan output had little effect on the amount of drift. Since the losses of spray liquid were approximately 80% for the radial emission system possibly only about 20% of the applied product was actually deposited onto the bushes. However, the deposited amounts would probably be higher in real conditions because with this experimental layout drift was determined only for the leeward row representing the worst-case scenario. In practice, the drifted liquid settles on 2–3 adjacent rows, being a source of secondary deposition, which overlays on the spray applied during the direct treatment. Although, there is currently no data on the distribution of secondary spray deposition caused by airborne drift in currants, in orchards such application has been shown to increase the primary application by 14% in the first row and by 8% in the following second row. Doubts exist; however, on the impact of the biological effectiveness of secondary deposition, bearing in mind that the drifted liquid settles on the outer part of the bush canopy, where an excess of PPP is observed anyway. However, there are no research results in this area.
Spray application and drift measurements during the field spray treatments of spatial orchard crops are inherently characterized by high variability due to varying plant sizes and unstable climatic conditions, particularly wind speed and direction. The structure of currant bushes makes it difficult for the spray liquid to penetrate due to large leaves in the outer zone of the bushes and small ones in the middle of the bush, which contributes to the variability of results. Despite these limitations, such measurements are considered more reliable than those performed in closed facilities and stationary conditions.

4. Conclusions

The obtained results showed that the two-row sprayer with adjustable air spouts of directed air discharge system produced similar spray deposit in blackcurrant bushes with much lower spray drift to the air compared to conventional axial fan sprayer. Although the superiority of the “off-set” system could not be proven, as the differences were not statistically significant, it was shown that the PPP drift losses for the “face-to-face” and “offset” systems were statistically significantly lower than those for the conventional sprayer, which is sufficient justification for the practical application of this technique in currant protection.
The spray drift from the directed air-jet sprayer was 25.1/32.2%, and from the conventional sprayer 76.9/81.8% at the lower/higher air output settings. The spray loss indicates the scale of possible airborne drift which can be transported long distances by the wind, away from the place of application. This kind of drift is a major source of surrounding area contamination and therefore is of great concern to local communities, especially those living in areas adjacent to fruit crop plantations. The presented research will contribute to increased effectiveness of spraying and will facilitate the implementation of the European Green Deal and the implementation of a 50% reduction in PPP use after 2030 in the EU.
No direct potential for PPP reduction has been identified, but environmental benefits may translate into effects resulting from growers’ participation in eco-agricultural systems.
An advantageous feature of the presented two-row sprayer is the possibility of remotely adjusting the range of the supporting air-jet according to the size of the currant bushes while the machine is operating. Besides, an important benefit is the ability to spray two rows simultaneously, which increases working efficiency by 40% and considerably reduces the costs of chemical protection of berry bushes. It should also be taken into account that greater efficiency and more effective use of the tractor’s power also results in lower CO2 emissions into the environment.
Due to the high nutritional value of blackcurrants research on new pesticide application techniques for berry crops should continue focusing on:
verification of the obtained results in biological efficacy tests,
the use of spray recycling techniques.

Author Contributions

Conceptualization, R.H. and G.D.; methodology, R.H. and G.D.; investigation, R.H. and W.Ś. and A.B. and A.G.; data curation, R.H. and P.K. and W.Ś.; writing—original draft preparation, R.H.; writing—review and editing, G.D. and P.K. and A.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was co-financed by the Polish Agency for Enterprise Development and carried out as part of the project POIR.02.03.02-14-0005/15—“Innovative two-row sprayer for the chemical protection of berry bushes in conventional and organic fruit production”.

Data Availability Statement

The data presented in this study are available from the corresponding author on reasonable request.

Acknowledgments

We would like to thank the AGROLA company in Płatkownica for their support in the construction of the sprayer prototype.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Experimental two-row directed air-jet sprayer (IO-PIB Skierniewice; ZHP Agrola): (a) General view; (b) air spout.
Figure 1. Experimental two-row directed air-jet sprayer (IO-PIB Skierniewice; ZHP Agrola): (a) General view; (b) air spout.
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Figure 2. Directed air-jet discharge system: (a) Scheme; (b) air spouts configuration: (A) “face-to-face”; (B) 0.5 m “offset” position.
Figure 2. Directed air-jet discharge system: (a) Scheme; (b) air spouts configuration: (A) “face-to-face”; (B) 0.5 m “offset” position.
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Figure 3. Conventional sprayer with a radial air-jet discharge system (Art. 35, ZHP Agrola—Poland): (a) General view; (b) axial fan.
Figure 3. Conventional sprayer with a radial air-jet discharge system (Art. 35, ZHP Agrola—Poland): (a) General view; (b) axial fan.
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Figure 4. Layout of filter paper collectors (a) for evaluation of in-bush spray deposit (no. 1, 2, 3, 4, 5, 6, 7) and off-target spray loss (airborne drift no. 1, 2, 3, 4, 5, 6, 7, 8; ground deposit: no. 1, 2, 3): (b) filter paper for spray deposit, (c) filter paper for airborne drift.
Figure 4. Layout of filter paper collectors (a) for evaluation of in-bush spray deposit (no. 1, 2, 3, 4, 5, 6, 7) and off-target spray loss (airborne drift no. 1, 2, 3, 4, 5, 6, 7, 8; ground deposit: no. 1, 2, 3): (b) filter paper for spray deposit, (c) filter paper for airborne drift.
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Figure 5. Vertical air-velocity distribution for two-row directed air-jet sprayer and conventional axial fan sprayer: (a) 1st gear; (b) 2nd gear.
Figure 5. Vertical air-velocity distribution for two-row directed air-jet sprayer and conventional axial fan sprayer: (a) 1st gear; (b) 2nd gear.
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Figure 6. Air-velocity distribution for: (A) “face-to-face”; (B) 0.5 m “offset” position—top view.
Figure 6. Air-velocity distribution for: (A) “face-to-face”; (B) 0.5 m “offset” position—top view.
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Figure 7. Average spray deposit on 7-th samples located in blackcurrant bushes, at lower air volume, produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 7. Average spray deposit on 7-th samples located in blackcurrant bushes, at lower air volume, produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 8. Average spray deposit on 7-th samples located in blackcurrant bushes, at higher air volume, produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 8. Average spray deposit on 7-th samples located in blackcurrant bushes, at higher air volume, produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 9. Average spray deposit on upper and lower leave sides at lower (a) and higher (b) air volume for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 9. Average spray deposit on upper and lower leave sides at lower (a) and higher (b) air volume for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 10. Spray drift measured on the frame located on the leeward side of the blackcurrant at lower (1) and higher (2) air volume produced by: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 10. Spray drift measured on the frame located on the leeward side of the blackcurrant at lower (1) and higher (2) air volume produced by: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 11. Spray drift measured on the frame located on the leeward side of the blackcurrant bushes row at lower (a) and higher (b) air volume produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 11. Spray drift measured on the frame located on the leeward side of the blackcurrant bushes row at lower (a) and higher (b) air volume produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 12. Spray deposit measured on the ground on the leeward side of the blackcurrant bushes row at lower (a) and higher (b) air volume produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
Figure 12. Spray deposit measured on the ground on the leeward side of the blackcurrant bushes row at lower (a) and higher (b) air volume produced by the sprayer fan for: “face-to-face” (A), “offset” (B) and conventional (C) air-jet emission system.
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Figure 13. Spray loss produced (%) by the sprayer fan for: “face-to-face”, “offset” and conventional air-jet emission system.
Figure 13. Spray loss produced (%) by the sprayer fan for: “face-to-face”, “offset” and conventional air-jet emission system.
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Table 1. Parameters of spray applications in blackcurrant plantations performed at spray volume 300 L ha−1 and travel speed 6.0 km∙h−1.
Table 1. Parameters of spray applications in blackcurrant plantations performed at spray volume 300 L ha−1 and travel speed 6.0 km∙h−1.
Air-Jet Emission SystemGearAir Volume
m3 h−1
Air Velocity
m∙s−1
Number
of Nozzles
Pressure
MPa
Directed air-jet (“offset”)112.000382 × 41.05
216.000442 × 41.05
Directed air-jet (“face-to face”)112.000382 × 41.05
216.000442 × 41.05
Conventional (axial fan)122.000282 × 41.05
231.000342 × 41.05
Table 2. The ANOVA summary table for data sets of spray deposit in blackcurrant bushes at lower and higher air volume, produced by the sprayer fan for: “face-to-face”. The denotation * marks not significant effects or interactions at p < 0.05.
Table 2. The ANOVA summary table for data sets of spray deposit in blackcurrant bushes at lower and higher air volume, produced by the sprayer fan for: “face-to-face”. The denotation * marks not significant effects or interactions at p < 0.05.
Source of VariationdfSum of SquaresPercent of TotaldfSum of SquaresPercent of Total
Lower Air VolumeHigher Air Volume
Spray deposit—spray emission
Main effects:
    L—Location6* 8,022,57421.676* 5,842,39214.29
    ET—Emission type21,117,9833.022183,1080.45
    L × ET121,963,3255.30123,063,0517.49
ERROR18946,888,898 189.0039,347,307
Spray deposit—leaf side
Main effects:
    LS—Leaf side 1* 3,929,10610.611* 1,854,9684.54
    ET—Emission type21,117,9833.022183,1080.45
    ET × LS2591,1031.602259,7450.64
Error20452,354,587 20446,138,037
Table 3. The ANOVA summary table for data sets of spray drift to the air measured on the frame located on the leeward side of the blackcurrant bushes row at lower air volume (1) and at higher air volume (2). The denotation * marks not significant effects or interactions at p <0.05.
Table 3. The ANOVA summary table for data sets of spray drift to the air measured on the frame located on the leeward side of the blackcurrant bushes row at lower air volume (1) and at higher air volume (2). The denotation * marks not significant effects or interactions at p <0.05.
Source of VariationdfSum
of Squares
Percent of Total
Spray drift (on the frame)
Main effects:
ET—Emission type 2* 8,364,52765.24
EA—Air assistance1* 192,6111.50
ET × EA2210,7811.64
Error1867,692,981
Table 4. The ANOVA summary table for data sets of spray drift to the air measured at 8 locations on the frame located on the leeward side of the blackcurrant bushes row at lower and higher air volume produced by the sprayer fan for: “face-to-face” The denotation * marks not significant effects or interactions at p < 0.05.
Table 4. The ANOVA summary table for data sets of spray drift to the air measured at 8 locations on the frame located on the leeward side of the blackcurrant bushes row at lower and higher air volume produced by the sprayer fan for: “face-to-face” The denotation * marks not significant effects or interactions at p < 0.05.
Source of VariationdfSum of SquaresPercent
of Total
dfSum of SquaresPercent
of Total
Lower Air VolumeHigher Air Volume
Spray drift (on the frame)—8 location
Main effects:
L—Location7* 998,30420.237* 860,11210.65
ET—Emission type2* 2,959,88859.972* 5,615,42069.51
L × ET14207,4284.2014* 1,817,84922.50
ERROR721,140,656 722,668,631
Spray drift (ground)—3 location
Main effects:
L—Location 2* 4,340,01840.692* 3,026,19737.84
ET—Emission type2* 2,800,33126.262* 2,874,22235.94
L × ET4* 5,959,66355.884* 6,747,21584.37
Error279,041,522 277,743,132
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Hołownicki, R.; Doruchowski, G.; Świechowski, W.; Bartosik, A.; Konopacki, P.; Godyń, A. Influence of Air-Jet Configuration on Spray Deposit and Drift in a Blackcurrant Plantation. Agronomy 2025, 15, 2360. https://doi.org/10.3390/agronomy15102360

AMA Style

Hołownicki R, Doruchowski G, Świechowski W, Bartosik A, Konopacki P, Godyń A. Influence of Air-Jet Configuration on Spray Deposit and Drift in a Blackcurrant Plantation. Agronomy. 2025; 15(10):2360. https://doi.org/10.3390/agronomy15102360

Chicago/Turabian Style

Hołownicki, Ryszard, Grzegorz Doruchowski, Waldemar Świechowski, Andrzej Bartosik, Paweł Konopacki, and Artur Godyń. 2025. "Influence of Air-Jet Configuration on Spray Deposit and Drift in a Blackcurrant Plantation" Agronomy 15, no. 10: 2360. https://doi.org/10.3390/agronomy15102360

APA Style

Hołownicki, R., Doruchowski, G., Świechowski, W., Bartosik, A., Konopacki, P., & Godyń, A. (2025). Influence of Air-Jet Configuration on Spray Deposit and Drift in a Blackcurrant Plantation. Agronomy, 15(10), 2360. https://doi.org/10.3390/agronomy15102360

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