Joe Dvorak 2016-10-25 00:29:08
There is clearly a market for organic and locally grown products. While agricultural professionals debate the merits of organic and local food production, grocery stores across the nation have added organic and local food sections. Consumers are buying organic and buying local, and demand for these products has increased substantially in recent years. The confluence of the organic and local food movements has led to a unique range of marketing opportunities—from local food sections in grocery stores to farmer’s markets and community-supported agriculture (CSA) programs. These venues provide more contact with customers and higher prices for producers who are able to meet the expectations of these customers. Small vs. large production systems Although CSA, farmer’s markets, and local food sections provide new markets for producers, they also place unique demands on production compared to more traditional systems. With CSA and local food, one big requirement is that farms must provide a diverse array of products (often vegetables) rather than specializing in only one crop. Keeping customers happy requires a variety of crops throughout the season. When you add the requirements of organic production, these operations begin to look considerably different from other agricultural systems. If someone with a background in traditional wheat, corn, or soybean production visits these operations, it becomes immediately clear that the work and machine use are very different. In these small, diversified production systems, a tractor is used nearly every day, but only for a few hours at a time and often at relatively low load. Because they can’t use synthetic herbicides, organic producers have to rely on mechanical cultivation, plastic mulch, crop rotation, and even hand weeding to control weeds. All of this translates into highly variable machine tasks that occur every day and continue all season. Compare this to grain crop equipment that is often run for long periods (upwards of 16 hours a day) for a couple weeks until a particular task is completed, after which the machine is parked and the producer moves on to the next task. In organic and local production systems, the available machinery is often ill-suited to the production requirements. It’s often older equipment re-purposed from other production systems. However, the criteria for selecting machinery are very different between traditional production systems and these new applications. For example, machine capacity, which is the area that a machine can work in a given amount of time (e.g., acres per day), is critical in grain production systems and is often constrained by horsepower. In organic and local production, machine capacity is determined by the width of the production plot, the type of weeding performed, and the speed at which the task must be performed in order to be effective. The maximum area that a machine can cover in a day is generally unimportant, as this level is rarely reached. The traditional mantra that has driven farm machinery development—“ bigger is better”—does not apply to local production systems. Local production systems also vary significantly from other farming systems in their economics. In diversified vegetable production for CSA, the revenue is between $15,000 and $20,000 per acre per year for operations in the 30 to 100 acre range. Clearly, the total revenue of these operations can be quite high, but as with all agriculture, the expenses are also very high. In addition, the nature of the expenses is different. The largest expense for local production systems is generally labor, with a significant portion of that dedicated to weed control. Machinery for small producers There are challenges in developing new machinery for these producers. First, these operations are geographically dispersed. Without concentration in a single location, the traditional interactions, from producers discussing best practices to businesses offering specialized products and services, become more difficult. Additionally, their market requires diversified production; therefore, while total revenue may be high, the revenue from any single crop is limited. Both of these factors mean that the expensive, California-style automation that creates highly specialized machines—such as a dedicated harvester for paste tomatoes—will not be applicable. Instead, the machinery that supports these producers must be flexible and support a wide variety of crops. Still, a growing market with significant revenue, high labor expenses, lacking a mechanical process for weeding, and ill-suited for current machinery options seems to be a perfect candidate for new types of machinery. Even more enticing is that these producers have considerable access to consumers. A machinery solution that improves the features of organic and local production in a way that consumers find appealing can be marketed directly to those consumers and provide a competitive advantage for producers. So, what do these producers need from their machinery? Since one of the primary drivers of labor cost is weeding, that task is perfect for mechanization. The basics of weeding are similar across a wide variety of crops, and advanced weeding implements are already available. While row crop cultivation has declined in the U.S., European companies like Steketee, Einböck, and Kress have continued development and currently produce high-speed, camera-guided precision row-crop cultivators with finger weeding attachments that can provide both intrarow and inter-row weed control in a wide variety of crops. The machine that pulls these implements need only be low power and operate for short durations, but it needs to be precise and capable of frequent use. Preferably, to create further labor savings, the machine would also reduce the need for an operator. The solar electric solution Considering all these factors, we began investigating an autonomous, solar-powered tractor for weeding in diversified, organic, local vegetable production. Its autonomous operation makes the system ideally suited for its intended application because it targets a primary cost: weeding labor. The tractor must be precise to reduce the chance of damage to high-value crops, but it does not need to be highly intelligent (i.e., capable of handling unanticipated situations). The tractor is low power, which limits its ability to cause damage to external structures. Human operators will also be within a few minutes’ walk and able to provide assistance if anything unusual occurs. The tractor only needs to be able to drive precisely, and in the event of a problem, stop and wait for human assistance. The operating duration and frequency, combined with the expectations of the target customers, make electricity an excellent option for powering this machine. After the oil embargo of the 1970s, agricultural engineers investigated using electrical power for agricultural field machinery. The findings at the time were that storage issues made electrical power impractical for general fieldwork, but that there were possibilities in utility work (frequent, short-duration tasks). Those findings have proven accurate. Indeed, modern farms have few electric vehicles; however, utility-type vehicles in other industries (e.g., fork trucks for material handling) have seen a shift from mostly internal combustion to electric drive trains. The duty cycle of our weeding machine closely matches the use of a utility vehicle. Operating for short durations requires batteries of a reasonable size and provides sufficient recharging time between tasks. Creating this electricity from solar power is the type of differentiation that customers of organic and local food would appreciate. Other researchers have established that direct power using vehicle-mounted solar panels is impractical, so a battery system makes more sense. A battery charger tied to the power grid might be all that is necessary to ensure that the tractor is operated with renewable energy, as many utilities provide options to purchase dedicated renewable energy. Another option is installing solar panels on the farm. Based on our tests, a 12 kW solar panel system (with a footprint of about 500 ft2) would supply enough energy to weed eight acres of diversified vegetable production, with enough excess energy to refrigerate the produce all year. Is this the future of organic and local production? Only time and the markets will be able to determine that. These production systems can certainly benefit from mechanization to decrease their labor costs, and they have the revenue and pricing power to make changes to their operations. Assuming the demand for local and organic food remains strong, this is an opportunity for machinery manufacturers to fill an as-yet unmet niche in the market. ASABE member Joe Dvorak, P.E., Assistant Professor, Department of Biosystems and Agricultural Engineering, University of Kentucky, Lexington, USA, Joe.Dvorak@uky.edu.
Published by ASABE. View All Articles.
This page can be found at http://bt.e-ditionsbyfry.com/article/An+Autonomous%2C+Solar-Powered+Tractor/2621124/350793/article.html.