Before purchasing: how to choose the right agricultural sprayer?

The use of machines in the field has contributed greatly to the execution of all activities necessary for the production of food, fiber and energy. Each stage of the production process – preparing the area for planting; implementation of culture; management of pests, diseases, weeds; harvest; post-harvest – requires specific equipment. Regardless of the size of the property, there is equipment specifically designed to assist in carrying out these activities. 

In grain production, special importance is given to equipment that ensures the health of crops, through the application of phytosanitary products and/or nutrients: sprayers. The sprayer is the equipment used most frequently during the harvest, which is therefore a great opportunity to optimize crop results.

When to purchase a sprayer 

The frequency of applications, the size of the area to be treated and the operational capacity of the machine are decisive for choosing the appropriate sprayer. To verify the operational capacity, the working speed that the field allows to operate and the total length of the bar are considered, combined with the number of daily hours in which it will be possible to apply (considering favorable weather conditions for the application, work shifts, dedicated times in displacements and preparation of the syrup).

The technologies embedded in this equipment aim to facilitate operation, providing the operator with some facilities that help with the quality of the service performed. Highlights include georeferencing signs, assisted steering, automatic cutting of spray sections, bar positioning sensors, efficient syrup agitation systems, maintenance of application quality when changing travel speed and/or tractor acceleration, valves special for pulsed spraying, with the possibility of adjusting droplet size regardless of changes in machine speed, sensors for localized applications (weeds).

Reservoir size and bars

Sprayers with larger capacity tanks are preferred when aiming to reduce the frequency of fuel stops and the time spent traveling. It is worth noting that the size of the sprayer reservoir must be compatible with the tractor's ability to pull the machine in all conditions on the farm, in movements and at points of greatest challenge for the group, such as terrain with irregular and inclined topography. Larger bars are preferred when the objective is to increase the operational capacity of the sprayer, that is, to increase the area applied per unit of time, in addition to directly influencing the crushing of the crop, given the reduction in the frequency of tractor tracks in the field. . The definition of the size of the bars must also consider the topography conditions (surface regularity and inclination), as vertical oscillations resulting from the movement of the tractor increase the risk of the ends of the bars impacting the ground. The shape and size of the plots also influence the size of the ideal bar: the smaller the plot, the more jagged and irregular, the greater the challenge for larger bars.

An undersized sprayer will result in use above the appropriate operational limits, such as very high working speed, very high spray circuit pressure, work in unsuitable weather conditions, compromising the quality of the application with consequent loss in the control of the damaging agent and productivity of the plant. culture. Furthermore, the chances of mechanical problems in the equipment increase as a result of use outside of its technical recommendations, reducing its useful life.

Sprayer Components

From the first sprayers used in the application of phytosanitary products to today's modern sprayers, some components continue to perform vital functions, such as the reservoir to hold the syrup, the pump to pressurize the liquid, hoses and branches to conduct and distribute the spray, and the spray tips, popularly known as nozzles. However, several components were inserted into the system, aiming to remedy any deficiencies or improve the way in which some activity is carried out.

The shape of the reservoirs and the material that constitutes them have been improved over time, with the aim of optimizing the mixing and homogenization of products in the syrup, avoiding “dead spots” of low movement of the syrup and predisposition to sedimentation, with smooth surfaces and low porosity, seeking to reduce particle retention and facilitate sprayer decontamination. 

The syrup agitation systems, so important for mixing the products inserted in the reservoir and keeping the syrup homogeneous from the beginning to the end of the application, have gained important improvements, with high capacity venturi type hydraulic agitators, dimensioned and positioned in a strategic way to contemplate all points of the reservoir, mechanical agitators also well sized and positioned, with the possibility of adjusting agitation levels according to the amount of syrup present in the reservoir or according to the command given by the machine operator. Everything to keep the quality of the syrup as high as possible.

The syrup pressurization pumps followed two distinct approaches, one seeking high energy efficiency, with high liquid displacement capacity, represented by centrifugal pumps; and another aspect that strives for greater linearity in the flow, regardless of the circuit pressure, characteristic of positive displacement pumps, represented by piston and diaphragm pumps.

The hydraulic circuit, through which the syrup is transported from the reservoir to the nozzles, received some components. High-capacity filters prevent larger particles from reaching the nozzles and causing blockages. The flowmeter provides accurate flow readings, allowing minute adjustments to the application. The valves and registers direct the syrup and regulate the pressure and, activated manually or automatically, allow important changes during application. Some of these valves are activated by actuators that open or close based on information coming from the georeferencing system, allowing the automatic cutting of sections, which results in significant savings in grout due to the reduction of areas with application overlap combined with the reduction of failures. This technology also makes specific applications possible according to pre-processed maps or based on commands coming from the machine's own sensors, in real time.

In the nozzle bodies, anti-drip valves eliminated waste and contamination resulting from the loss of syrup accumulated inside the branches after stopping the application. The nozzle filters, as long as they are well sized, allow the application to continue, avoiding stops to unclog the spray tips due to particles that may settle in the solution exit holes. The different nozzle models and flow rates allow a detailed choice regarding the required droplet size, minimum and maximum working pressures, propensity for droplets to drift, droplet uniformity, direction of projection of the jets and durability of the nozzles according to the material used. in its manufacture and the conditions that occur in the work, such as physical properties of the grout and working pressure. 

Some other technologies present in the nozzles have revolutionized the quality of the application, such as the valves that allow the opening and closing of each of the sprayer nozzles, reducing the length of the sections to the minimum possible (space between nozzles), which gives the machine the possibility to extremely reduce overlaps and failures, in addition to enabling large product savings in localized applications. Another technology whose adoption has been growing in recent years is pulsed spraying (Pulse Width Modulation – PWM), which in addition to the benefit of independent nozzle opening, can change the flow rate of each nozzle without the need for changes to the circuit pressure, which favors the maintenance of droplet size, which is influenced by the change in spray pressure.

Choosing the right sprayer is crucial to ensuring the effectiveness of agricultural operations and the health of crops. Considering factors such as the frequency of applications, the size of the area to be treated, the operational capacity of the machine and the embedded technologies can maximize results and work efficiency. A well-sized sprayer, with quality components and advanced technologies, contributes to a uniform and precise application, saving time and resources in addition to extending the useful life of the equipment. Therefore, it is essential to carry out a careful analysis of the farm's specific needs before investing in a boom sprayer, ensuring that the equipment chosen is suitable for the field conditions and challenges. Ultimately, choosing the right sprayer is a strategic investment that can result in healthier and more productive harvests, ensuring the sustainability and profitability of agricultural production.

*Per Fabiano Griesang, product specialist at Jacto