Evaluation of UAV sprayer quality in compared to common sprayers ‎in cotton field

Introduction: Cotton is one of the most important agricultural products in the world, which has caused diseases and pests due to continuous cultivation and geographical and climatic conditions. Control of cotton pests with ground spraying equipment results in physical plant damage, lower crop yields and quality, water loss, and pesticide use. The use of drone spraying is one of the new methods of precision agriculture that plays a role in sustainable agricultural production and reduces the use of pesticides that damage soil and plants. The aim of this study is to investigate the efficiency of UAV sprayers in cotton cultivation and compare these sprayers with other general cotton sprayers.
 
Meterial and method: In this study, a drone sprayer was compared with two sprayers commonly used in cotton production (tractor mounted sprayer and lance mounted sprayer). This project was based on a split-plot design in a completely randomized design with three replications. The main treatments of the experiment included the type of sprayer at three levels (tractor mounted sprayer, sprayer with lance and UAV sprayer) and the sub-treatments included the plant position at three levels (top, middle and bottom of the plant). The image processing method was used to evaluate the quality of spraying, including the numerical median diameter (NMD), volumetric median diameter (VMD), spray quality, and percentage of surface coverage using a water sensitive card (WSC). The WSCs were placed at three plant locations at the bottom, middle, and top of the cotton plant on the boll branches. Immediately after spraying, WSC were collected from the field and scanned separately with a scanner for use in ImageJ® image processing software.
 
Results: The highest number of droplets under the influence of sprayer type was observed in the lance sprayer with about 1361 droplets in all levels of the cotton plant, which was not significantly different from the boom sprayer (1000 droplets). Depending on the type of sprayer, the lance sprayer and the high pressure sprayer were expected to have the highest number of drops. The UAV sprayer had the lowest number of drops with 317 drops. There is no significant difference between the three different top, middle and bottom positions of the crop in terms of NMD in the drone sprayer and the boom mounted tractor sprayer. In the tractor mounted sprayer, the top plant position has the largest NMD, which is significantly different from the middle and bottom plant positions. Also, the evaluation of the three sprayers in each of the three plant positions showed that there is a significant difference between the tractor-mounted boom sprayer and the lance sprayer in the upper plant position, while there is no significant difference between them and the UAV sprayer. There is also no significant difference between the three sprayers in the middle and lower position of the plant in NMD. According to the results, in the different treatments, 50% of the droplet sizes have a diameter less than 200 μm. According to the index for spray quality, the sprayer with lance with a value of 3.62 is the one with the lowest spray quality. According to this index, the best spray quality is the tractor mounted sprayer with a value of 2.43. In terms of spray quality index, the drone sprayer and the lance sprayer as well as the tractor mounted sprayer and the lance sprayer are not in the same group. In addition, the tractor mounted sprayer had the best uniformity of VMD. In this study, the best NMD was obtained with the drone sprayer. The highest percentage of spray coverage was recorded with the lance sprayer at a rate of 5.5% at the top of the plant position. The lowest percentage of spray coverage at the top of the plant was measured with the drone sprayer at a rate of about 2.94%. The effective field capacity and field efficiencies of the three sprayer types showed that the highest field efficiency occurred with the drone sprayer at 78.95%, which was 1.38 and 2.31 times that of the tractor-mounted boom sprayer and lance sprayer, respectively.
Conclusions: The drone sprayer had the best spraying performance, and when the farm is large, the drone sprayer was the fastest spraying machine. The tractor mounted sprayer is the best option when there is no pest outbreak or force majeure.
At the pest outbreak or the impossibility of tractor movement in the field due to rain or irrigation, the best and fastest method is drone sprayer. At the same situation, and on unavailability of drone sprayer, The only option on the table is lance sprayer, although it has the lowest spraying efficiency. In terms of spraying speed, water saving and pest control; using a drone sprayer was the best option.
Introduction: Cotton is one of the most important agricultural products in the world, which has caused diseases and pests due to continuous cultivation and geographical and climatic conditions. Control of cotton pests with ground spraying equipment results in physical plant damage, lower crop yields and quality, water loss, and pesticide use. The use of drone spraying is one of the new methods of precision agriculture that plays a role in sustainable agricultural production and reduces the use of pesticides that damage soil and plants. The aim of this study is to investigate the efficiency of UAV sprayers in cotton cultivation and compare these sprayers with other general cotton sprayers.
 
Meterial and method: In this study, a drone sprayer was compared with two sprayers commonly used in cotton production (tractor mounted sprayer and lance mounted sprayer). This project was based on a split-plot design in a completely randomized design with three replications. The main treatments of the experiment included the type of sprayer at three levels (tractor mounted sprayer, sprayer with lance and UAV sprayer) and the sub-treatments included the plant position at three levels (top, middle and bottom of the plant). The image processing method was used to evaluate the quality of spraying, including the numerical median diameter (NMD), volumetric median diameter (VMD), spray quality, and percentage of surface coverage using a water sensitive card (WSC). The WSCs were placed at three plant locations at the bottom, middle, and top of the cotton plant on the boll branches. Immediately after spraying, WSC were collected from the field and scanned separately with a scanner for use in ImageJ® image processing software.
 
Results: The highest number of droplets under the influence of sprayer type was observed in the lance sprayer with about 1361 droplets in all levels of the cotton plant, which was not significantly different from the boom sprayer (1000 droplets). Depending on the type of sprayer, the lance sprayer and the high pressure sprayer were expected to have the highest number of drops. The UAV sprayer had the lowest number of drops with 317 drops. There is no significant difference between the three different top, middle and bottom positions of the crop in terms of NMD in the drone sprayer and the boom mounted tractor sprayer. In the tractor mounted sprayer, the top plant position has the largest NMD, which is significantly different from the middle and bottom plant positions. Also, the evaluation of the three sprayers in each of the three plant positions showed that there is a significant difference between the tractor-mounted boom sprayer and the lance sprayer in the upper plant position, while there is no significant difference between them and the UAV sprayer. There is also no significant difference between the three sprayers in the middle and lower position of the plant in NMD. According to the results, in the different treatments, 50% of the droplet sizes have a diameter less than 200 μm. According to the index for spray quality, the sprayer with lance with a value of 3.62 is the one with the lowest spray quality. According to this index, the best spray quality is the tractor mounted sprayer with a value of 2.43. In terms of spray quality index, the drone sprayer and the lance sprayer as well as the tractor mounted sprayer and the lance sprayer are not in the same group. In addition, the tractor mounted sprayer had the best uniformity of VMD. In this study, the best NMD was obtained with the drone sprayer. The highest percentage of spray coverage was recorded with the lance sprayer at a rate of 5.5% at the top of the plant position. The lowest percentage of spray coverage at the top of the plant was measured with the drone sprayer at a rate of about 2.94%. The effective field capacity and field efficiencies of the three sprayer types showed that the highest field efficiency occurred with the drone sprayer at 78.95%, which was 1.38 and 2.31 times that of the tractor-mounted boom sprayer and lance sprayer, respectively.
Conclusions: The drone sprayer had the best spraying performance, and when the farm is large, the drone sprayer was the fastest spraying machine. The tractor mounted sprayer is the best option when there is no pest outbreak or force majeure. At the pest outbreak or the impossibility of tractor movement in the field due to rain or irrigation, the best and fastest method is drone sprayer. At the same situation, and on unavailability of drone sprayer, The only option on the table is lance sprayer, although it has the lowest spraying efficiency. In terms of spraying speed, water saving and pest control; using a drone sprayer was the best option.