Template:Chapters 7.3
7.3 -Backpack Sprayers for Smallholder Farmers
Jessica Szulc,University of Guelph, Canada
Suggested citation for this chapter.
Szulc,J. (2022) Backpack Sprayers for Smallholder Farmers, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction to Backpack Sprayers
The practice of using chemical pesticides plays a significant role in decreasing the loss of agricultural products caused by pests, adding to the value and quality of produce, and promoting a safer market supply (An et al., 2020). A convenient and reasonably affordable option for reducing the damage caused by diseases and pests is implementing a backpack sprayer to distribute chemicals, such as pesticides or herbicides (Ratcliff, 2001). Backpack sprayers are especially effective in supplying chemicals to plants in smaller areas and are typically used on farms with fewer than 2-3 Ha (Calvo et al., 2019). Most tanks are made from polyethylene plastic, which is the industry standard since it is resistant to corrosion from chemicals and does not weigh a lot (Ratcliff, 2001). Manually powered backpack sprayers include a liquid-holding tank, pump and pumping lever, pressure-holding chamber, hose, and wand with a control valve (Ratcliff, 2001). The liquid-holding tank itself is not pressurized (Ratcliff, 2001). Instead, a pump carries the liquid from the tank into a pressurizing chamber (Ratcliff, 2001). When the valve on the wand is squeezed by the operator, the liquid from the pressurizing chamber is released (Ratcliff, 2001). On the other hand, engine-powered backpack sprayers do not require manual pumping, which helps to sustain the consistency of the pressure (Ratcliff, 2001). High pressures can be reached, but most backpack sprayers operate at 15-95 psi (Ratcliff, 2001). Some sprayers have built-in pressure regulators (Ratcliff, 2001). If one does not have this feature, purchasing a pressure-regulating valve or spray-management valve would be beneficial to regulate the pressure of a manually powered backpack sprayer (Ratcliff, 2001). One of the most important parts of a backpack sprayer are the nozzles since they affect the flow rate, equality of application, coverage, and extent of drift (Ratcliff, 2001). Nozzles can be changed to suit the operator’s application needs; investing in quality nozzles is crucial (Ratcliff, 2001).
Benefits for Smallholder Farmers
Backpack sprayers are commonly used by smallholder farmers because they are reasonably affordable, can be properly maintained, adaptable in the field, and accessible in developing countries (Calvo et al., 2019). Due to their size, they are convenient for fields that are inaccessible by other equipment (Calvo et al., 2019). For example, in the Mediterranean region, backpack sprayers are often used due to the presence of many sloped fields and uneven ground, where a tractor-mounted sprayer cannot be used (Calvo et al., 2019). Further, the air-assistance from the fan in the backpack sprayer allows for more coverage of the spray droplets on plants (Calvo et al., 2019). Backpack sprayers can be shared between farmer organizations and village collectives to share costs since they are only used a few times a year by an individual farm (though can range up to 5-12 times per year in the citrus orchards of China) (An et al., 2020), and can be easily transported if stored properly (Greess, 2012). Another benefit is that most critical parts are individually replaceable, such as the wands and the nozzles (Greess, 2012). Therefore, if one piece breaks or requires maintenance, a farmer does not need to purchase a new backpack sprayer, which decreases the operating costs (Greess, 2012). Backpack sprayers also do not require much space for storage if they are safe from being damaged by nearby items (Greess, 2012). Lastly, by purchasing another tank, an operator will be able to spray two products on one job without emptying the sprayer (Greess, 2012). Separating one tank for herbicides and one for insecticides is helpful to avoid contamination from chemicals that are challenging to rinse out (Greess, 2012).
Analyzing Safety & Sustainability
Major risks are posed to the operator due to the vibration from engines and other moving parts being transmitted to the body (Kouchakzadeh and Beigzadeh, 2015). Intense vibrations on the head, spine, and hand can cause discomfort and fatigue, which can lead to physical, physiological, and musculoskeletal disorders after months and years of continuous use (Kouchakzadeh and Beigzadeh, 2015). One study suggested that the maximum amount of time a backpack sprayer can be used is one hour; therefore, this equipment is not sustainable for users working long hours alone (Kouchakzadeh and Beigzadeh, 2015). However, the intensity of the negative effects depends on several factors: direction, acceleration, magnitude, frequency, and duration of usage (Kouchakzadeh and Beigzadeh, 2015). Another study discovered that the head, hands, back, and lower legs were the body parts with the highest exposure to pesticides (An et al., 2020). Exposure to certain chemicals can result in burning eyes, nosebleeds, blistering, and burns (Konthonbut et al., 2020). In addition to vibrations and pesticide exposure, the noise from backpack sprayers is extreme; values larger than 100 dB were measured at the operator’s ear (Calvo et al., 2019). Furthermore, exposure risks were found to be significantly higher for farmers compared to technicians; probably due to the personal operating habits of the farmers (An et al., 2020). Developed countries require pesticide applicators to attain a pesticide applicator license and receive professional training (An et al., 2020). In contrast, poor farmers are typically untrained with low levels of education (An et al., 2020). This indicates that educating poor farmers and creating standardized operation protocols, such as using the correct personal protective equipment (PPE) including respirators, are important to decrease the exposure risk to pesticides through skin or inhalation (An et al., 2020). Practices such as using an engine-powered backpack sprayer and standing upwind can reduce inhalation exposure, and wearing a long sleeve shirt, long pants, boots, latex gloves, and balaclava can decrease skin exposure from mist or leaks (Konthonbut et al., 2020).
Critical Analysis of Risks & Benefits
There are many common problems associated with backpack sprayers; however, simple solutions and practices, such as regular maintenance, can allow the operator to receive maximum results and value from their purchase (Greess, 2012). Weight is a concern for backpack sprayers, especially for women farmers. Varying due to tank capacity, sprayers normally weigh 6.8-20.4 kg when they are fully loaded (Ratcliff, 2001). Most have a tank capacity of 15 L, and each gallon increases the total weight of the sprayer by 3.6 kg (Ratcliff, 2001). So, women farmers can adjust the weight of the backpack sprayer depending on how much weight they can carry. It is important to start off by purchasing a quality product that can operate for long hours and tolerate tough chemicals (Greess, 2012). Spray wands that are made from brass are stronger than plastic, and standard tips are inexpensive compared to product-specific tips (Greess, 2012). The availability of repair and replacement parts is key since a clogged filter inside of the tank can cause interruptions, eventually leading to damage and repair expenses (Greess, 2012). One study analyzed the discomfort of vibrations from backpack sprayers and noticed that the oldest machine with the least amount of maintenance produced the greatest discomfort and vibration on the back, which emphasizes the requirement of maintenance for safety and sustainability (Calvo et al., 2019). Several inappropriate situations have been common in which backpack sprayers were used to open gates, move trash and debris, and dragged on the floor, resulting in parts breaking (Greess, 2012). Damage is also common when sprayers are exposed to cold temperatures; even in warmer climates, a spray should not be left in a tank overnight (Greess, 2012). Another problem is the training required by low literacy farmers, since training is critical to maximize the potential benefits of this equipment and learn correct operating procedures to avoid repair expenses (Greess, 2012). This issue can be solved through the distribution of picture-based manuals since they do not require literacy, technical skills, or knowing a certain language (Devkota et al., 2020). This technique is very effective since picture-based lessons are easily comprehensible for most individuals (Devkota et al., 2020).
It is evident that backpack sprayers are advantageous, especially for smallholder women farmers, since they are lightweight, shareable in terms of costs and use, easy to operate, accessible in developing countries, and convenient on sloping fields and uneven grounds (Calvo et al., 2019). They are also inexpensive: see Table 1 below, where the price ranges from $12.50-$104.28 USD. Backpack sprayers are affordable and easy to use in comparison to larger farming equipment (Calvo et al., 2019). However, if backpack sprayers are used improperly by untrained farmers or not maintained when needed, harm can be caused to the operator and result in increased costs (Greess, 2012). The key to improving the safety and sustainability of backpack sprayers is education since many farmers with low levels of education are not following proper procedures or wearing appropriate PPE (An et al., 2020). The risk of pesticide exposure can be diminished through increasing awareness and providing education about proper operation methods (An et al., 2020). Educating smallholder farmers about such standards would greatly decrease the risks and ensure benefits, but a challenge arises in making the information easily accessible or free. In addition, the dangerous vibrations caused by extended use of backpack sprayers could be improved by design solutions, such as pneumatic isolators (Kouchakzadeh and Beigzadeh, 2015). Re-thinking the design using participatory approaches would enable a low-cost tool to remain accessible to those in developing countries without negative health effects.
Source Links for the Products Above:
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Useful Links for Getting Started
Information and calculator for calibrating sprayers: http://www.omafra.gov.on.ca/english/crops/sprayer/ep75.htm#hand
Demonstration on sprayer maintenance:
https://www.youtube.com/watch?v=87m6cIuHUo4&ab_channel=PESTEDGeneral information on backpack sprayer use: https://royalbrinkman.com/knowledge-center/mechanical-equipment/backpack-sprayer
Suggestions on choosing a sprayer: https://www.backyardboss.net/best-backpack-sprayer/ and
https://sprayerexpert.com/backpack-sprayer-guide/Website for comparing backpack sprayers:
https://www.agriexpo.online/agricultural-manufacturer/backpack-sprayer-10865.htmlReferences
1. An, X., Liu, X., Jiang, J., Lv, L., Wang, F., Wu, S., & Zhao, X. (2020). Exposure risks to pesticide applicators posed by the use of electric backpack sprayers and stretcher-mounted sprayers in orchards. Human and Ecological Risk Assessment, 26(8), 2288–2301. https://doi.org/10.1080/10807039.2019.1675493
2.Devkota R., Odame H.H., Fitzsimons J., Pudasaini R., & Raizada, M.N. (2020). Evaluating the effectiveness of picture-based agricultural extension lessons developed using participatory testing and editing with smallholder women farmers in Nepal. Sustainability, 12(22), 9699.
3. https://www.mdpi.com/2071-1050/12/22/9699
4.Greess, A. (2012). Manual sprayers - selection, use and maintenance for optimal results. International Pest Control, 54(3), 142–143. https://www.proquest.com/docview/1432314893?pq-origsite=primo&accountid=11233
5.Calvo, A., Preti, C., Cutini, M., & Deboli, R. (2019). Vibration on the backs of mistblower operators: is it only a (dis)comfort question? Biosystems Engineering, 185, 4–14. https://doi.org/10.1016/j.biosystemseng.2019.01.010
6.Ratcliff, C. (2001). Backpack sprayers. Grounds Maintenance, 36(3), 49–59. https://www.proquest.com/docview/220784808?pq-origsite=primo&accountid=11233
7.Konthonbut, P., Kongtip, P., Nankongnab, N., Tipayamongkholgul, M., Yoosook, W., & Woskie, S. (2020). Paraquat exposure of backpack sprayers in agricultural area in Thailand. Human and Ecological Risk Assessment, 26(10), 2798–2811. https://doi.org/10.1080/10807039.2019.1684187
8.Kouchakzadeh, A., & Beigzadeh, Y. (2015). Permitted working hours with a motorised backpack sprayer. Biosystems Engineering, 136, 1–7. https://doi.org/10.1016/j.biosystemseng.2015.05.005