The move to reduce chemicals has also met with the approval of the supermarkets they supply who are keen to promote quality assurance and traceability.

At Frankly Farm, White House Lane, Fishtoft, Boston, F Pettitt & Son grow 320 acres of mixed vegetables-cauliflower, calabrese, brussel sprouts and cabbage. All the produce is sold to supermarkets through Old leak Growers Co-operative.

Four years ago, a 12 metre wide OPICO Comb Harrow was introduced as a replacement for chemical weed control for all the vegetable crops. A multi-purpose tool, the Comb Harrow consists of fine spring tines, mounted on a contour flexing frame. Designed specifically for weeding crops and reducing chemical costs, it can also be used to break up capped soil or as a conventional harrow for seedbed preparation and harrowing.

The system at Franklyn Farm is to start 10-12 days after the cauliflowers, for example, have been transplanted.

Eight or nine passes are carried out until the crop is well established and the plants become too large to use the Comb harrow. They then bring in the Scuffler, a 10-row hydraulic folding inter-row hoe of their own design, for deeper hoeing.

Richard Pettitt, who runs the business in partnership with his father, Frank, calculates that the Comb harrow notches up 1600 to 2000 acres/year. "In terms of savings on the expense of spraying, the harrow has paid for itself four times every year," he calculates.

As a result of its wide, 12m operating width, the implement covers 21 rows at a time which reduces the number of passes through the fields and tractor-wheel compaction. On a good day he reckons to cover 60/70 acres.

The Comb harrow is pulled by either a John Deere 6400 or 6800 tractor and, says Richard Pettitt, is easy to use. "We all drive it but you need to be a competent driver. It is a precise machine, which means it is gentle on the plants.

"It is a great cost saving without a shadow of doubt," says Richard Pettitt, who is currently buying a new replacement machine form OPICO. "It has also eliminated manual labour on the job."

Moreover it does not hinder crop growth. "Chemicals will check the crop in the cold and through the year," he pointed out.

Richard Pettitt says the rake has paid for itself four times every year

Richard Foster believes the Comb Harrow seems to stimulate plants' growth

Cuts costs, stimulates growth

Just a few miles away, Richard Foster of Kirton End near Boston, is in his third season with a 6m wide Comb harrow. Again his motive for buying the machine was primarily to reduce the cost of chemicals and although he hasn't given up spraying totally, he reckons he has achieved cost savings of at least 30%.

"The Comb Harrow seems to stimulate the plants growth," he said, "and I'm sure more organic growers should be using it."

Richard Foster farms about 200 acres including 30 acres of cauliflower, 30 acres of calabrese, 8 acres of Savoy cabbage and a few acres of spring green. All produce is destined for the supermarkets via the Univeg Group.

"Three weeks after planting, once the roots are in, we start with the Comb Harrow to take out the weeds. At this early stage we go through regularly once a week or every 10 days." Correct speed is critical, he emphasises, " The tines must vibrate through the soil so you can't go too slowly. At 5/6 mph the tines loosen up the soil, remove the weeds, and stimulate plant growth."

Once the plants are more established, Mr Foster brings in an inter-row cultivator and/or sprayer. "All our vegetables now have 100% traceability - everything can be tracked back to the field where it was grown," he says.

He finds the Comb Harrow reliable and easy to operate. "It's easy to hook up, handle, and lowers itself down easily - I wouldn't be without it." It covers the ground quickly and has also been used on wheat crops where it has worked well.

Richard Foster estimates the savings over the cost of hand hoeing are about 90%. "Obviously we still do a bit of this but you can't get the labour very easily. The old hands who knew what they were doing have gone and its an expensive business nowadays."