18 July 1998


A ready market and lower input costs convinced one Norfolk farmer that conversion to organic potato production was the right road, as Edward Long discovered.

ORGANIC potato growing is a risky business and choice of an appropriate variety and careful management are vital for success. But it is worth taking trouble as there is a separate demand-led market ensuring the crop will always sell.

This is the experience of Norfolk potato grower Don Morton who has 8ha (20 acres) of organic and 20ha (50 acres) of conventionally grown crop on 240ha (600 acres) of sand at Bagthorpe near Kings Lynn.

"I have grown potatoes organically since 1988," he says. "In the mid-1980s I was having to invest in an ever increasing level of inputs for cereals just to stand still, then came a huge harvest and we were left with an embarrassing surplus of grain that no-one wanted. So I decided to set up an organic operation. Potatoes was the simplest crop option to start with, and there was a ready market for organically grown produce."

The initial 8ha (20-acre) block earmarked for conversion was cropped with a white clover/ryegrass/cocksfoot ley mixture. In the first year this was grazed by a 35-cow beef herd, and by 120 sows in the second.

Mr Morton says the conversion process was easy as both the beef animals and the pigs were already on the farm, and potatoes in the rotation.

Machinery hitch

"We also had the equipment, but when we ploughed out the grass in the spring for our first organic crop of Cara we unearthed two machinery-related problems. Grass blocked the stone separator, and because of the concentration of stones in the furrows it was difficult to find soil to bulk up the crop to achieve effective weed control."

The first organic Cara crop yielded 30/ha (12t/acre) or about 60% of the 14ha (35-acre) conventionally grown crop. The organic premium more than offset the yield penalty.

This was an encouraging start. Since then an extra field has entered the conversion cycle each year. Now 100ha (250 acres) of the farm have gone through the process and the rest is farmed conventionally.

Apart from the organically grown potatoes, the non-converted land is cropped with 52ha (130 acres) of sugar beet, 24ha (60 acres) each of wheat and barley on seed contracts, and 6ha (15 acres) of onions. The organic block grows 16ha (40 acres) of wheat and barley, 10ha (25 acres) onions, 6ha (15 acres) carrots plus smaller areas of parsnips, sweetcorn, red beet and brussels sprouts.

Although Cara was used initially it was soon discovered to be far from ideal for organic production on the lightland farm. It is susceptible to spraing and there is a high population of the free-living nematodes which spread the trouble. Varieties this year include Premiere, Sante and Nicola. Cara is still grown on the rest of the farm, alongside Saxon and Fianna.

"When selecting varieties for organic production great care has to be taken to balance the needs of the market with what will suit a no-chemical regime," Mr Morton says. "For a conventional crop most varieties can be grown, so long as they are what customers want, but choosing one for our converted block is complex. It needs to be a vigorous grower to get away from the inevitable weeds, with some in-built ability to cope with blight, and on this farm it must not be susceptible to spraing. It would be folly to use the blight-susceptible King Edward or spraing-prone Desiree. Premiere has a good level of both blight and spraing resistance and Sante seems reasonably resistant to most things."

These are planted before the conventional crop is put in, organic seed from Scotland and Somerset is used. While some organic growers prefer to plant late to give more time to clean the land and reduce rhizoctonia risks, Mr Morton wants his crop to go into warm moist seedbeds to get it off to a flying start to outrun the spraing-spreading nematodes. Cara and Saxon on non-organised land are protected by nematicide.

Fertiliser for conventional crops includes 225kg/ha (180 units) nitrogen, a little less for Cara, 250kg (200 units) phosphate, 375kg (300 units) potash and 88kg (70 units) magnesium. The organic crop benefits from the residues from the ley which is given fym and seedbed Kieserite supplies magnesium.

Weed threat

"Our biggest threat is weeds, particularly knotgrass and fat hen which are competitive and cause harvesting troubles. Modern machinery is not designed to cope with weeds. We manage by going through two or three times with a Cousins fixed-tine ridger modified so stones are not thrown out of the wheelings and soil is kept in the ridges. This is 80% effective."

Blight is a constant worry; its build-up marks the end of the growing season at Bagthorpe. While a full programme of fungicides is used for the conventional crop, the only option for the organic potatoes is use of copper and sulphur sprays. Usually three or four are applied; after mid-season the job is suspended as it probably does more harm than good.

Mr Morton reckons input costs for his organic crop, after accounting for spreading fym, mechanical weed control and flailing, are about half of what is charged to his conventional crop. Organic seed is between 35% and 50% more expensive, but there are big savings by not using sophisticated fertilisers, nematicides, weed-killers and blight fungicides.

"Ten years experience has shown that while conventionally grown potatoes on this farm yield around 22t/acre our organic crop should, in a reasonable season, give 12t. Premiums vary a lot from a minimal amount to 100% or more. The big attraction for me is that the market for organic potatoes is separate from the mainstream and as demand is strong my crop should, so long as quality is satisfactory, always sell," Mr Morton says.

Don Morton: attracted by the separate market for organic potatoes.

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