24 July 1998

Big investment pays off in high quality tomatoes

Massive tomato production

demands a massive

greenhouse and that is just

what fresh produce supplier

Hazlewood VHB has installed

in West Sussex.

Brian Lovelidge reports

FANCY a gross income of £617,750/ha (£250,000/acre)? That is what fresh produce grower Hazlewood VHB is achieving from its new 9.3ha (23-acre) glasshouse in West Sussex.

The facility was completed in time for planting tomatoes last autumn. With computerised environmental control and heating, plus top-notch growing technology its total cost was about £8m.

The site at Runcton Nursery, Runcton, West Sussex, is claimed to be in the highest light intensity area in the UK – essential for a high yielding protected crop.

Heating pipes, which also serve as rails for the battery-powered picking trolleys, cover 115km (72 miles), with hot water supplied by two 27t, 2MW gas-fuelled engines. These also generate electricity, 5% of which is used for running the glasshouse, the rest going to the National Grid.

In case of engine failure there are three gas-fired back-up boilers generating 33m kilocalories. Both boilers and engines can also be fuelled with kerosene should the gas supply be interrupted. That is how important it is to maintain the optimum temperature for peak tomato production.

The carbon dioxide-rich exhaust gas from the engines or boilers is piped into the glasshouse to enrich its atmosphere up to three-fold, to as high as 1000 ppm. This boosts the plants metabolism, producing stronger growth, which increases yield by 10-15%. It also usually improves the fruits shelf life.

"The carbon dioxide concentration in ambient air averages around 340ppm," explains John Hall, Hazlewood VHBs senior operations manager. "Natural gas burns very cleanly so we do not have to worry about toxic fumes going into the glasshouse, although the system has detectors that shut it down if a toxic gas is present in the exhaust."

Hazlewood VHBs managing director, Arnold Lewis, admits the new glasshouse could have been built much more cheaply. But its high specification pays handsomely in terms of yield and fruit quality, he insists.

Two-thirds of the house is devoted to round tomato production, the rest being truss and plum types. Round tomatoes are on target to produce about 60kg/sq m (240t/acre) worth £617,750/ha (£250,000/acre). Although other varieties are lower yielding, their higher value means a similar income.

"Our short-term aim is to average 260t/acre. We think that we can go higher in the longer term," declares Mr Lewis. "We could reach 280t/acre now with a higher yield potential variety, but it would be like growing turnips. There is always a trade off between yield and quality.

Materials are recycled wherever possible. For example, at the seasons end the rockwool and glasswool slabs are steam sterilised and reused or sold. A fifth of the water not taken up by the plants is collected, sterilised with ultra-violet light, filtered, mixed with fresh water, and used again.

Tomato plants have a prodigious thirst, each consuming about 330 litres (72.6gal) in its lifetime or 2 litres a day (3.5pt a day) during peak production. That is equivalent to 720,000 litres (158,380gal) for the entire 9.3ha crop.

At the end of the season not even the old plants or vines are wasted. They are finely chopped and composted off-site by contractors.

Environmental conditions in the new glasshouse are accurately controlled by computer. Generally those ideal for tomato production tend to be unfavourable for pest and disease activity. But pests in particular, notably the two-spotted spider mite, white fly and leaf miners, would still pose problems without the effective use of introduced predators and parasitoids.

"We spend a small fortune on these creatures. But we do not have to spray for pests anywhere near as much as we used to," asserts Mr Lewis. "We improve our bio-control of pests every year and although we are not quite down to zero insecticide use we have a fair chance of getting to that stage by 2001. The main threat to plant health is botrytis."

Fruit in the new glasshouse is picked into trays on battery-powered, four-wheeled trolleys carried on the two heating pipes along each alley. During the peak production period, lasting from about mid-June to mid-August, up to 50 pickers are employed seven days a week.

The crop is graded and packed at the companys nursery at Littlehampton about 15 miles away. From there it is transported to supermarket depots countrywide and to Marks and Spencer stores in France.

lNext week we take a look at the growth of Hazlewood VHBs fresh produce business and prospects for the future. &#42


&#8226 9.3ha housing 362,000 plants.

&#8226 Top sunlight area in UK.

&#8226 Glass transmits 90% of light.

&#8226 600t/ha yield worth £1000/t.

&#8226 Hot water to buffer temp.

&#8226 CO2 level 3 times normal.

&#8226 Predators cut insecticide use. None needed by 2001?

&#8226 Many materials recycled.

&#8226 Hazlewood VHB grows 35% of UK tomatoes.

Hazlewoods 9.3ha glasshouse measures 1.5km around the perimeter, with 40,000 sheets of high transmission glass letting in 90% of incident sunlight. Total roof weight is about 1000t.

Tomato plants in the new glasshouse at Runcton are pollinated by bumble bees held in special hives, explains operations manager, John Hall. Annual output is almost 600t/ha, with produce worth over £1000/t.

Exhaust gas from the heating plant trebles the CO2 content of the glasshouse, boosting tomato yield and shelf life.

Cropping cycle

The glasshouse is occupied for all but about two weeks of the year, when old plants are removed, houses thoroughly cleaned, new growing medium and drip fertigation system installed and 362,000 new plants set out. Plants are raised by specialist nurserymen in the UK and Holland. Seed sown in the second half of October arrives in the growing house three to four weeks later. Plants fruit from February to the second week of November.

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