By Erdal Ozkan, Ohio State University Professor and Extension Ag Engineer
Much of the pesticide applied today using conventional spray equipment for pest control in floral, nursery, orchard, vineyard and other specialty crop productions is wasted in a number of ways. Most of this waste is due to the sprayers used and how they are operated.
Using conventional sprayers in orchards, for example, the growers simply turn on the sprayer at one end of the row of trees and stop spraying at the other end. The spraying is done continuously, regardless of the gaps between the trees. This gap could be rather wide in some cases, up to 30% of the area sprayed. This means we may waste at least 30% of the pesticide sprayed using conventional sprayers.
Moreover, in a nursery, or an orchard we not only have gaps between trees, we also have a tremendous variation in the size and shape of targets we spray: some short, some tall, some bushy, some slender. Even if trees we spray are the same size and shape, we still have a great variation in leaf densities of these trees from April to June or July. The conventional sprayers cannot take any of these variations in target conditions into consideration, and continue spraying a fixed amount of pesticide per acre. This is not only an economical loss to growers, it is also bad for the environment for both air and water pollution.
Some of the spray discharged from conventional sprayers deposits on the ground, increasing the risk of contaminating nearby water resources. In addition, a significant portion of the spray discharged from the sprayer may totally miss the intended target, become airborne, and create pollution of air with pesticides. Unfortunately, when using conventional orchard sprayers, it is extremely difficult to avoid these potential problems because all the nozzles are turned on and remain on throughout the spraying operation regardless of the variations in shapes, sizes and canopy conditions of the targets.
These are the reasons why a team of researchers in Ohio designed and field-tested an automated variable-rate precision sprayer that can recognize the gaps between targets, delivers pesticides to exactly where the target is and varies the application rate according to target size, shape and foliage density with minimum operator involvement. It makes these split-second decisions on-the-go when the sprayer is traveling at a speed of up to 5 miles per hour. The intelligent sprayer described in this article was designed and developed by a team of engineers and technicians located on the Wooster campus of The Ohio State University’s College of Food, Agricultural, and Environmental Sciences (CFAES). The team is led by Dr. Heping Zhu, an Agricultural Engineer at USDA-ARS unit located at this site, and supported by a number of talented technicians, students and international scientists who contributed to the development of the Intelligent sprayer.
What makes this sprayer “intelligent”?
The components that make this sprayer intelligent include: a high-speed laser scanning sensor, a travel speed sensor, a sophisticated automatic nozzle flow rate controller, an embedded computer, a touch screen, a control switch box, and 40 variable-rate nozzles on two sides of the sprayer. The laser sensor detects the target and provides data for the computer to process and eventually make assessments about tree canopy conditions using an algorithm developed in-house by the design team. The algorithm also determines the optimum amount of spray to be discharged from each one of the 40 nozzles independently according to the foliage conditions at their designated canopy sections. The touch screen monitor in the cab displays the sprayer travel speed, total discharged spray volume, spray width, and the number of active nozzles. Operators, if needed can modify spray parameters on the touch screen, and by using a set of toggle switches can choose sprayer outputs from one or both sides of the sprayer, or they can turn the intelligent mode on or off.
Does the intelligent sprayer really work?
Field experiments at the Ohio Agricultural Research and Development Center (OARDC) Horticulture farm in Wooster were conducted to see how well the intelligent sprayer would perform in terms of providing uniform spray coverage on targets, and reducing spray losses in the air and on the ground compared to a conventional sprayer. Results were very impressive. The intelligent sprayer reduced airborne spray drift by up to 87%, and reduced spray loss on the ground by 68% to 93% compared to a conventional sprayer.
Although these are impressive numbers confirming savings in pesticide cost and reduced spraying time, the success of the intelligent sprayer will eventually lie in its reliable accuracy performance over a long period of use operating under varying spray application conditions, and most importantly, its performance in providing satisfactory pest control. To address these two concerns, the intelligent sprayer has been tested for pest control efficacy, reliability and durability in four commercial nurseries, one fruit farm and one vineyard in Ohio; one nursery in Oregon; one nursery in Tennessee; and one vineyard in Napa Valley, Ca. These field tests have shown that the pest control efficacies obtained from the intelligent sprayer were comparable to those of conventional sprayers, while the intelligent sprayer reduced pesticide use by more than 50% and reduced spray deposition variations due to changes in tree structure and species at different growth stages. The intelligent sprayers used at these sites were operated by the growers themselves with technical support from the development team. At this point, growers seem to be satisfied with the ease of use of the intelligent sprayer, and have actually seen significant reductions in, cost savings and chemical waste reductions, while achieving at least the same level of efficacy they get when using their conventional sprayers.
What kind of savings do we get when an intelligent sprayer is used?
Field tests conducted showed that pesticide use per acre was reduced by 47% to 70%, resulting in an annual average pesticide cost savings of $230 per acre in ornamental nurseries. There are also some indirect cost savings associated with using the intelligent sprayer. For example, because it uses less spray than the conventional sprayers during spraying the same area, the intelligent sprayer saves growers’ time by requiring fewer spray tank refills. This allows growers to cover more acres per tankful compared to the area sprayed with a conventional sprayer. Under some severe insect infestation situations, this added spraying time may be even more important than the actual dollars saved as a result of reduced pesticide use. Considering the significant savings in chemical costs alone, a grower with a 100-acre field nursery can recoup the total investment cost of the sprayer within one year.
What is next for the intelligent sprayer project?
The initial objective of the team who contributed to this project was to design and develop one type of an intelligent sprayer, and test its performance in a variety of application conditions. This has been accomplished. The intelligent sprayer research team’s new objective is to explore ways to make the intelligent sprayer concept an affordable option to growers who do not want to give up their old but functioning conventional sprayer. To meet this objective, the intelligent sprayer design team has developed a kit that can be retrofitted on almost any conventional orchard sprayer that specialty crop and orchard growers use today.
When is this technology going to be commercially available?
With its unique design, the Intelligent Sprayer is the first functioning automatic spraying system of its kind in the world. It has the proven potential to positively impact economic wellbeing of specialty crop growers in terms of reduced pesticide cost and time savings, while protecting the environment from potential pollution resulting from excessive use of pesticides. The intelligent sprayer has already won two design awards, a national award by The American Society of Agricultural and Biological Engineers, and the 2018 Innovator of the Year award from CFAES. The intelligent sprayer design and testing project has received significant and continuing grant funding from USDA, and support from growers. However, manufacturers are still somewhat reluctant to incorporate this technology in their existing sprayers they sell. Manufacturers would like to see one or two more years of efficacy data to be totally convinced that the technology works. The intelligent sprayer development and testing team is continuing their efforts in sharing field evaluation data for the intelligent sprayers with equipment companies. Several sprayer manufacturers have already visited the intelligent sprayer development site and have expressed enthusiasm for the technology and their interest in adapting this new technology to their sprayer designs. Growers who want to participate in efficacy testing and evaluation of the intelligent sprayer, and the manufacturers interested in exploring ways to produce sprayers with intelligent features should contact Dr. Heping Zhu, the project team leader (email: Heping.Zhu@ARS.USDA.GOV)
Erdal Ozkan, Professor and Extension Ag Engineer, can be reached at 614-292-3006, or firstname.lastname@example.org. This column is provided by the OSU Department of Food, Agricultural and Biological Engineering, OSU Extension, Ohio Agricultural Research & Development Center, and the College of Food, Agricultural and Environmental Sciences.