With the constant growth of the world population, there is also a growing need for food and this leads to farmers seeking high productivity in crops. Several factors help to increase productivity, such as the use of pesticides, which influence the protection of the crop against weeds, pests and diseases in general. However, the use of pesticides has led to a growing demand from society to obtain increasingly healthier foods that have less impact on the environment. Despite technical guidelines on how to apply in a technical and judicious way, in the field, what is often observed is a lack of knowledge and information regarding the use of the application technology technique.
Antuniassi and Gandolfo (2001) mention that periodic inspection programs for sprayers began a long time ago, but around the 1970s the idea came to fruition. In the mid-1990s, the results of these inspections could already be observed, such as the work of Ganzelmeier and Rietz (1998), who evaluated sprayers throughout almost all of Europe, where currently many countries require sprayer owners to carry out periodic inspections of their equipment. .
The Agricultural Mechanization Laboratory of the Instituto Federal Catarinense - Rio do Sul Campus, carried out inspections and calibrations of mounted tractor-type boom sprayers, commonly used in family farming, widely present in the Alto Vale do Itajaí region (SC).
The assessments followed the methodological bases developed for the Periodic Sprayer Inspection Project - IPP (Gandolfo, 2002; Antuniassi and Boller, 2011).
12 sprayers were inspected in different municipalities in the Alto Vale do Itajaí region. The equipment inspected was classified as mounted sprayers, as they are coupled to the three-point hydraulic system of agricultural tractors. For each sprayer evaluated, a form was filled out with information about the use of the equipment: model, brand, year of manufacture, expected spray volume, machine working speed, spacing between nozzles, working pressure, engine speed, calibration method of the machine, as well as notes on the inspection and calibration of the machine.
To check the calibration of the sprayers, initially the application rate that the sprayer should apply was defined and, subsequently, calibration was carried out. Therefore, to evaluate the application rate, the speed used in the application (km/h), the flow rates found at each tip (L/min) and the distance between nozzles (m) were determined.
To calculate the application rate, speed was determined by measuring the time needed to travel 50 meters, transformed into km/h. The average flow rate at the tips was obtained using data on individual flows.
The evaluations were carried out with sprayers using only water, the data obtained together with the information from the machines were computed in a database, generating specific reports for each piece of equipment evaluated. The data collected in the field were subjected to exploratory analysis, through a descriptive and qualitative analysis.
The data on the items evaluated during sprayer inspections were computed and organized, identifying the percentage of sprayers that had inappropriate items in the inspections carried out, as shown in Table 1.
Below, we describe the main problems found in the 12 pieces of equipment inspected.
Among the equipment inspected, 50% showed some inadequacy, such as twisted, cracked or broken hoses that make up the spraying system, which can compromise the flow of syrup in the pipes and affect the spraying dynamics. The jet was projected onto a hose in 41,7% of the sprayers inspected, compromising the spraying dynamics.
Of the equipment inspected, 66,7% had problems with at least one anti-drip on the spray bar.
Protection of moving parts was present in 58,3% of the sprayers inspected, this is a safety item and extremely necessary to protect cardans, belts and pulleys that can cause injuries to operators. If these are not observed, installation as soon as possible is recommended.
When evaluating leaks in the spraying system, it was found that there were leaks, whether in filters, hose connections, tanks and pumps, in 41,7% of the sprayers inspected.
The pressure gauge on 75% of the sprayers had the appropriate observation scale. In other words, the working pressures were between 25% and 75% of the maximum value shown on the pressure gauge.
The spacing between the spray tips was within the acceptable range, a variation of ±10% in relation to the nominal value, in 75% of the equipment inspected. The tips within the same set evaluated were, in 91,7% of cases, of the same type, therefore considered adequate.
The line filters of 75% of the equipment did not present cracks, breaks, dents or twists in the filter element and did not present damage to the body, therefore considering them as adequate. The suction filters of 75% of the equipment did not present cracks, breaks, dents or twists in the filter element and did not present damage to the body, therefore considering them as adequate.
This item considered the individual flow of each end, with variations of ±10% in relation to the average being acceptable. In relation to this variation limit, only 33,3% of the equipment was considered adequate. In cases where the flow variation between the ends was greater than 10%, immediate maintenance was required. Regarding the age of the equipment, it was observed that 41% of the sprayers evaluated were between six and ten years old and 33% of these had between one and two years of use, indicating a large amount of equipment renewal in the region.
According to Table 2, when evaluating the application rate of the inspected equipment, described by the municipalities in the Alto Vale do Itajaí region, we observed that 58,3% of applications were below the desired parameter, being called underapplication, which consists of volume 5% or more below the recommended value. Of the total number of sprayers evaluated, 16,7% of these were not used following a technical recommendation for application volume. The average overapplication value found was 14,1%.
In most inspections, the flow rates were irregular, mainly sub-applications were found, which could compromise the control of pests and diseases, compromising the formation of drops and interfering with the application rate. When the flow rate of the spray bar has a very high coefficient, such as 49,8%, there is no uniformity in the application of pesticides, with values that are outside the reference flow rate (Table 3). The high coefficient of variation index may be due to several factors, such as the useful life of the nozzles, the type of product formulation applied and the preparation of the syrup, but mainly regarding the correct cleaning of the equipment.
The variability between the nozzles as recommended by Gandolfo (2002) is 10%, therefore, it was observed that the coefficient of variation of 58,3% of the sprayers evaluated was within the acceptable value according to the methodology.
The calibration of 83,3% of the equipment evaluated was inadequate, with these being under or overapplying, mainly due to failures in the calibration of the sprayers, problems due to clogging often occurring with products with dispersible granules, wettable powder and also solids found at the time. sprayer supply. Other problems identified at the time of calibration were due to the lack of pressure at which the sprayers worked, losses due to leaks in hoses, connections and/or filters.
Among the sprayers inspected, all showed inadequacy in at least one item examined, with the anti-drip sprayers, the flow of the tips and the conservation of the hoses being the three main failed items, with 66,7%, 66,7% and 50%, respectively.
The calibration of 83,3% of the equipment must be corrected, and these are under- or over-applied, mainly due to tip flow problems. There is a need to carry out periodic inspection programs on sprayers in the Alto Vale do Itajaí region, identifying and correcting the topics explained and instructing producers on the use and maintenance of their machines.
Leonardo Düsterhöft, José Carlos Kusma, Fabrício Campos Masiero, Djeimes Luiz Sadowski Celante and João Célio de Araújo, IFC – Rio do Sul
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