Novel heating, lighting and harvesting techniques for strawberry production were the highlights of a one-day tour following the recent Global Berry Congress, writes Steven Vale.
On the second day of the Global Berry Congress, participants joined one of two study trips. The Fruit Grower opted to visit the Loos family that grows strawberries and asparagus for The Greenery, and then crossed the border to Belgium to tour the Hoogstraten Research Station, before visiting what is claimed to be the largest food supermarket in the Netherlands.
There are believed to be 300ha of glasshouse strawberries in the Netherlands, but only six growers are using growing lights; they are used on 2.1ha of the 3ha of glass belonging to the Loos family. Located near the Dutch town of Breda, Arno Loos told delegates that they grow a mix of varieties, including Elsanta, Sonata, Triumph and Arabella.
The family aims to work as organically as possible and, with two crops each year, has an average production of about 15kg/sqm, most of which is destined for The Greenery. Other notable points include a series of carbon dioxide hoses suspended between the gutters, and vertical air ducts that help to re-circulate carbon dioxide by drawing it down from the top of the 5m-high structure and releasing it 40cm above the floor.
However, the real news in this glasshouse concerns the heating system. The business burns around one million cubic metres of gas to heat the 3ha glasshouse. All the gas needed to do this is generated from an on-site biogas installation, that is the result of a unique partnership.
The 50:50 mix of farm slurry and organic waste required for the digester comes from four partners. Established in 2011, and operating as BioMoer, the Loos family is one of them and all old strawberry plants end up in the digester, along with asparagus waste. Two dairy farmers supply slurry, while the fourth partner, an arable farmer, provides potato and onion waste. The digester is fed with a total of 25,000 tonnes of material per year. The methane gas created is pumped to a combined heat and power generator that, in addition to providing a plentiful supply of hot water, also generates enough green electricity (2MW) for 6,000 homes, which they sell to the national grid. The Loos nursery buys back electricity to power the growing lights, and the unique project is claimed to reduce greenhouse gases by about 12,000 tonnes/year.
Strawberries were also on the agenda at the Hoogstraten Research Station, just a short drive across the border in Belgium. The three main crops grown in the area are strawberries, sweet peppers and tomatoes, and these are also the three main crops at the research facility.
The visit began with a look at the strawberry harvesting robot being developed by Octinion, a commercial research and development company. Chief Executive Tom Coen outlined the background to the project and explained the detailed plans. The strawberry harvesting robot first appeared in Europe in September 2016; it uses a combination of camera-guidance/GPS techniques to locate a ripe fruit, followed by an electrically-powered arm and gripper to pick it. One of the most challenging parts of the project was to develop a technique that turns the fruit through 90 degrees to break the calyx. Tests to find out the exact pressure required were conducted with researchers at the University of Leuven.
Tom Coen says it is easy to change the gripper to suit different fruit sizes and that the robot is designed to work in all glasshouses and with all the main varieties. Most of the trial work has been done with Elsanta, where the fruit picking rate, without damage, is expected to be around 70%. “We need well-spaced fruits,” added Tom. “Driscoll’s Lucia is another variety suitable for harvesting robotically, and the robot will probably pick up to 90% without damage. Ultimately, the goal is to pick much higher percentages without damage.”
The picking robot provides an opportunity to document a mass of information. For example, it is possible to input the exact location of each strawberry into a yield map, and harvest prediction is then possible. Also, the robot can detect diseased fruit, that can then be harvested by a separate gripper to avoid contamination.
Designed to work on tabletops, the development of the strawberry harvesting robot is driven by rising labour costs and the difficulty of recruiting seasonal labour. Tom reckons that the resulting labour shortage following Brexit could lead to interest in the strawberry picking robot, and there has also been interest from the USA.
“80 per cent of the strawberries consumed in the USA are soil-grown in California. The produce has to be transported long distances, and some growers feel it is better to use tabletops and shift production closer to the markets.” Also, labour costs are expected to rise by 50% by 2022, which could drive the sector towards tabletop production. “Some large growers are already experimenting with them, and these systems are ideal for the strawberry picking robot,” said Tom.
The company is close to unveiling a pre-production version. Smaller and faster than the prototype, and capable of picking a fruit every five or six seconds, Tom Coen reckons that it may ultimately be possible to reduce this to one fruit every three seconds. “This is about the same time it takes someone to pick manually,” he said.
Tom envisages that the autonomous harvester will operate for 16 hours/day, with three robots/ha picking 80-90 tonnes/year. It is envisaged that the robot would pick for two hours followed by a 45-minute battery recharge, but it could also be made available with a continuous battery charging system. If the speed of one fruit every six seconds is not fast enough, it may be possible to add a second robotic arm to double capacity.
Regarding costs, the company is looking to offer the robot through a leasing contract. Typical manual picking costs in the Benelux countries vary from €0.75/kg to €1/kg (50-60 fruits). Exact costs are not yet available, but they are likely to be in the region of 0.015 Euros/fruit.
The plan is to test six pre-production units with potential customers in September 2017, with a view to rolling out the first 10 or 20 pilots in early 2018. The company hopes to find local test sites for half of them, with the rest spread out, and is keen to find a British grower. Tom Coen is quietly confident of selling over 50 units in 2019, and will be disappointed if his company is not making one robot per week within the next few years.
Although still without a name, Octinion’s strawberry picking robot is clearly coming, and so too is another autonomous machine – a picking platform that can be used for a wide range of tasks including spraying, that will be available commercially this autumn.
Looking further ahead, the strawberry harvesting robot could be joined by other autonomous fruit-harvesting machines. The next step, to do the first experiments and to gather data as to what is possible with other berries, including raspberries and blackberries, is planned for this year. “This is the reason that we reduced the size of the gripper, making it easier to pick smaller fruit.”
LEDs on trial
Participants were given a tour of the remainder of the Hoogstraten Research Centre by newly-appointed director Tom van Delm, who had been a strawberry researcher for the previous eight years.
He explained that growers are hungry for information about new strawberry varieties. “Accounting for around 75% of the total area, Elsanta is still the main variety in Belgium, and is good for everything, except for early crops,” he said. In the early season, there is a trend away from Clery to Sonata, but researchers are also looking at a wide range of other newcomers, including Magnum and Malling Centenary.
One of the most interesting parts of the tour was a look at the work being done with LEDs. One study, that had just finished with Sonata as the main variety, was looking at different numbers, intensities and light recipes, to try to find the best combination and costs for winter production. Currently, a novel growing system containing two levels of strawberry gutters is being tested. Underway for a couple of years, so far, the results point to higher yields from the plants on the upper level, and reduced yields below, where natural light levels are around 30% lower, but total yields/sqm increased remarkably. “The plants were less vigorous, used less water and the disease pressure was higher,” said Mr van Delm. Last winter, LEDs were suspended below the high-rise gutters to make up for the light shortfall in a crop planted in December. “So far, the plants on the upper and lower levels are using the same amount of water, and the plants on the lower level are looking good,” he said.
Varieties and the investigation of new technologies such as LED lighting are some of the research topics under investigation at Hoogstraten, but many other studies are in hand, looking at pest and disease control using biological control organisms such as beneficial insects, water-use optimisation, fertilisation, energy efficiency and growing techniques.
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