Urban farming - Technology gains

As UK researchers continue to investigate the viability of high-intensity growing, Gavin McEwan talks to growers who have already taken the plunge.

Vertical growing: Iglo Foods Group is trialling VertiCrop system used at Paignton Zoo - image: Paignton Zoo
Vertical growing: Iglo Foods Group is trialling VertiCrop system used at Paignton Zoo - image: Paignton Zoo

The use of cutting-edge science and technology to allow crops to be grown year-round, quickly, with lower inputs and closer to their end markets is entering the horticultural mainstream at an increasing pace.

Maintaining that momentum is the goal of LED 4 Crops, an industry research facility that opened last May at Stockbridge Technology Centre (STC). A partnership between the North Yorkshire research organisation, glasshouse and equipment specialist CambridgeHOK and Philips Lighting, it is researching the viability of growing herbs, leafy salads and strawberries among other crops under LEDs.

CambridgeHOK general manager Tim Haworth explains: "It's a stepping stone between the industry and the pure science being done by the plant biologists in universities that we hope will come up with commercially viable solutions, leading to commercial installations.

"And that's already taking place. There will be installations going in the next two years, particularly in areas like plant propagation where a high degree of specification and uniformity is needed, and also in areas where the resulting crop is not tall, so you can look at vertical [multi-layered] growing. We will see this happening quite quickly."

Specific lighting "recipes" can further be used to trigger morphological responses such as promoting or delaying flowering or affecting flower stem length, Haworth explains. Another attraction of growing under LEDs is the potential they offer to extend the season for UK-grown crops, given their lower energy consumption than conventional sodium lighting, he adds.

"You can also introduce inter-lighting within the crop because the heat given out by the lights is low," says Haworth. "That's very useful in 'tall' glasshouse crops like tomatoes, peppers and cucumbers, where it can keep the lower leaves active. Ordin­arily, a 3m-high tomato plant receives less and less light as you go down the plant." Describing the LED 4 Crops facility as "the biggest of its kind in the world", he adds: "It gets very regular visits, which lead to phone calls."

Two trends that will drive the uptake of the technology are the increasing understanding of the effect of different light recipes on crops' growth and behaviour, and the falling cost of the technology. "Growers will never say it's affordable, but costs are coming down and the technology can only improve," says Haworth.

Burgeoning interest

STC chief executive Graham Ward adds: "There is a lot of interest in it, but for many growers it's not until they see it in practice that it becomes real for them." Ward shared a conference platform with Hull City Council's head of environment and transport and others at last November's Humber Expo Week, and added that council representatives had also visited the LED 4 Crops site. "Given the levels of investment likely to be required, it may be venture capitalists who are the ones who will make it happen on a commercial scale," he suggests.

Elsewhere, Finland — a country whose southern extremities lie parallel with the Shetland Isles, yet which meets a sizeable proportion of demand in its home market for fresh salad vegetables — has been at the forefront of low-energy intensification. Finnish LED developer Valoya has provided salad grower WS Bentley with supplementary lighting to enable the West Yorkshire company to grow pea shoots between October and February.

"We've had two winters with them and have no issues to report," says managing director Jan Bentley. "We did extensive testing of the available lighting solutions as we wanted the right light spectrum for our plants that would also offer high light intensity and mobility. With Valoya's LED lights we got the best quality of pea shoots quickly, while achieving the significant energy savings we were after. Though since then even more efficient models have become available."

Specific spectra

Valoya representative Sanna Näveri adds: "Our research has shown there is no simple answer to say which light in general is the best for the plant, but we have developed different kinds of spectra for different purposes."

As LEDs generate little heat, they can be used close to the crop, allowing multiple tiers or plants to be grown in a small space. But this is not what the company has opted for, Bentley explains. "If we did, we would use different LED lighting as that would then be the only light source." He adds: "It's been a good experience and has generated a lot of interest among other growers who weren't convinced it could be economically viable."

But high-intensity "factory" growing is not just about novel lighting formats. In the unlikely surroundings of Paignton Zoo Environmental Park in Devon, a vertical growing format originally designed to keep the zoo's animals in fresh greens is now being trialled by Birds Eye owner Iglo Foods Group with a view to adopting the format on a larger scale to feed humans.

The VertiCrop system from Canada's Alterrus Systems enables leafy plants to be grown hydroponically on multiple tiers while continually rotating them to ensure equal dosing and access to natural light. The two companies have been trialling basil, spinach and other greens since last summer, and they are about to begin discussions about how to scale up production.

"It's a great opportunity for optimising all the inputs," says Birds Eye head of European vegetable procurement James Young. "There's no waste water, no need for any pesticides and, because it is in a controlled environment, the water and nutrients are optimised and circulated through the system. Because the crops are grown indoors, they are not affected by the weather and can be grown without pesticides."

The VertiCrop system could enable Birds Eye to grow crops throughout the year, he explains. "All our factories are geared towards having high throughputs during short periods. If we could have a continuous flow of material through the year, it would be a much better use of factory utilities." Young says installing vertical growing sites next to Birds Eye packing facilities would also save transport costs and could reduce its field-to-frozen time.

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