Issue link: https://read.dmtmag.com/i/401644
36 NOVEMBER 2014 GOOD FRUIT GROWER www.goodfruit.com An effort to introduce variable-rate fertilizer applications in orchards was 20 years ahead of its time. by Geraldine Warner P recision agriculture techniques are every- day tools in row crop farming, but they have been slower to catch on in tree fruits. In 1994, Quincy, Washington, orchardist Jim Fleming tried out a small variable-rate fertilizer applicator that had been developed by Cenex to fit between tree rows. Fleming recalled that it worked well. After using a full-size machine to apply a pre-plant treatment to the ground where he was planting a new block, he used the smaller machine for a couple of years after the trees were planted. His soil is very variable with some areas of caliche in the upper soil layer and some deeper down. "I thought we had real uniform growth of the trees," he said, recalling that the nursery trees were unsorted and were not very uniform at planting. "I thought they did real well." Allan would also like to know how much light is hitting the orchard floor at a given time of day so he could iden- tify areas of the canopy that aren't getting enough light. One of the problems in terms of mapping variation in an orchard is that it can be difficult to pick up GPS sig- nals in the interior because of the trees and the trellises, he said, so there needs to be technology to address that. Allan said the technology is not at a point where it is easy for growers to implement. "But I think if someone was willing to go to work on this, there'd be a pretty good market. The basic problem with precision agriculture is we do not have out-of-the-box equipment that will work inside the canopy." Craig O'Brien, a grower at Prosser, Washington, said that about a decade ago, university researchers and rep- resentatives from John Deere brought an autonomous vehicle to test at his orchard. One of the challenges was that it was difficult to pick up satellite signals inside the orchard canopy. Though O'Brien finds the technology interesting, he thinks it will be difficult to integrate it into orchards because of all the unpredictable factors, such as sprin- klers, insects, and the wind, that scientists don't have to deal with in a lab. But research on new technologies for tree fruits is under way. Dr. Jingjin Zhang developed a technique for measur- ing how much sunlight comes through the tree canopy as part of her doctoral project at WSU's Center for Preci- sion Agriculture and Automated Systems. Her device uses Lidar remote sensing technology (see "Precision Ag Tools") mounted on a bar that can be driven up and down rows on a four-wheeler fitted with GPS. WSU horticulturist Dr. Stefano Musacchi is doing research with the machine in orchards with the goal of identifying the optimum pruning intensity for trees based on the amount of light reaching the orchard floor. He envisions that an orchard supply company might provide light mapping as a service to growers. However, it could be five years before the technology is ready to use. Bruce Allen, president of Columbia Reach Pack in Yakima, is already doing site-specific farming the old-fashioned way. He has employees go through the orchard with paint to identify trees and weak spots that need attention. Allen expects to be using drones with sensors, once the licensing and operational issues are resolved, but said the first thing that's needed is a way to collect yield data for specific parts of the orchard, he said. That would help them identify low-yielding areas as well as allow them to measure the impacts of practices they use. "If you have a weak spot, maybe you can change the fertilizer or the water and get the trees in more of a bal- anced state, but you don't really have the yield data that's very specific on a block," he said. "With yield data, you can measure what the economic benefit is versus what the economic cost was. It's the missing link." Gathering detailed yield data would be more compli- cated in tree fruits than in row crops because, in addition to tonnage, growers need to know the size and color of the fruit, which affect their returns. Data overload Karen Lewis, Washington State University extension specialist, said there are plenty of monitoring technolo- gies available, but the risk is getting overwhelmed with too much data. It has to be processed and analyzed to make it useful. Ideally, the data would be accessible wirelessly via a smartphone or tablet. Dr. Jim McFerson, manager of the Washington Tree Fruit Research Commission, also stressed that informa- tion must be actionable. Along with the hardware, there must be software that translates the data into something that horticulturists can use. "Drones are the superfood of technology right now," he said. "That's fine, but I think it's overselling the plat- form. The harder part is: What are we measuring and how are we developing decision models based on that infor- mation? It's easy to imagine a drone out there buzzing through the orchard. It's a lot less dramatic when you say, 'I have 12,000 images of apples. What am I going to do with them?' " • Time's