Darren and Julia Quenault took their first delivery of non-organic cattle feed a few weeks ago. After nine years of organic dairy farming, they decided to convert back to conventional, and give up their organic status, at the end of last year.

The reason was simple. “Cattle feed costs were excruciatingly expensive and we just couldn’t absorb them,” says Julia. “We’re saving £1,800 a month. We couldn’t have continued, we would have had to put up prices significantly, and we didn’t feel we could burden consumers with an extra 12% on the price of milk.”

The Quenaults are not alone. Even as demand for organic food remains high, the farmers producing it are falling by the wayside. And the results of their transition might cause anyone else considering it to think hard. Since they made the switch almost eight weeks ago, sales of the milk, cheese, cream and ice cream produced by the couple, their 60 Jersey cows and 10 staff (including their son) have held up.

And yet organic remains a powerful brand. So what are farmers like the Quenaults to conclude? Julia says how important their organic status was to their customers remains an open question, but that many local people are aware of problems with conventional farms. Chief among these is the high level of nitrates in the water supply, which has been linked to the intensive use of fertilisers on potatoes.

“There have been surveys about what matters to consumers. Is it food produced locally, animal welfare, the environment or price?” she says. Organic standards mean farmers are forbidden from using chemical herbicides, pesticides and fertilisers, and the use of medicines such as antibiotics on animals is controlled. Lower yields and higher costs are offset by a combination of the produce’s retail price premium, and subsidies paid to farmers to reward their environmental stewardship and protection of wildlife.

“Organic was an extra selling point for us, but now that we’re established, we hope it won’t matter too much. Organic is a really hard thing to explain. It means a lot of things, and you can’t sum it up in a few soundbites. We believe in the organic ethos, but it was an extra niche aspect for us. There are lots of reasons why people buy our milk.”

The Quenaults’ farm was certified by one of the main British certification bodies, Organic Farmers and Growers, but differences in Jersey’s subsidy regime mean their situation is different from that on English, Welsh and Scottish farms. After a period when they were threatened with the prospect of no subsidies whatsoever, the Jersey government offered an amount equivalent to that paid in England. “We asked for more because Jersey is one of the most expensive places to produce food,” Julia says. “It was frustrating more than anything … I think they have been short-sighted.” There is now just one organic milk producer left in Jersey.

Although the Quenaults’ decision was specific to conditions in Jersey, they represent a wider trend. UK government figures show that while organic food sales have bounced back from the low that followed the 2008/9 financial crash, the amount of land being farmed organically in Britain continues to shrink. In 2013, the last year for which data are available, land in the process of being converted to organic fell by 24%, with fully organic land falling by 3.9%. The number of producers and processors of organic food fell for the fifth year in a row, by 6.4%, and the number of organic sheep, pigs and cattle also fell.

Sales of organic food in the UK rose by 4% in 2014. Photograph: Martin Godwin

At the end of last year, four trustees resigned from the Soil Association, the campaigning charity and biggest certification body, and launched a public attack on the organisation’s direction, accusing it of failing to champion the producers and growers it is meant to represent. Last month a report by the European Environment Agency highlighted huge disparities between countries and the fact that British organic farming has stalled: while 3.3% of land is farmed organically in the UK, the same figure as in 2000, countries such as Austria and Spain have seen sharp rises (to 18.5% and 7.5%), while the number of UK farmers and certified processors making organic food products stands at 6,072, down from 7,567 in 2009.

So why, when UK organic sales rose by 4% in 2014, the second consecutive year of growth, are producers giving up? And could more generous European subsidies, to be paid from next year, tempt them back?

Jon Birchall is a farming consultant in Shropshire and Herefordshire, working on contract farming agreements (where labour and machinery are hired via a third party), and is responsible for 3,000 acres of mixed crops, dairy and beef cattle across eight farms. Among his clients is a dairy farmer who converted back to conventional from organic 18 months ago. Previously Birchall worked in Kent, managing a 1,500-acre farm that converted back to conventional in 2013, after six years of growing organic food.

He says he arrived in Kent with an open mind, looking forward to a challenge. But by the time he got there, the farm was struggling to control weeds in its fields of wheat, spring beans and triticale. “With the livestock [cows and sheep] it worked very well,” he says. “But on the cereal side, without any chemical means of weed control, we simply couldn’t get on top of it.”

Birchall is not against organic farming, and believes it possible that the problems he experienced in Kent were the result of the conventional system used previously, with its heavy reliance on herbicides. He describes himself as sceptical rather than disillusioned, and he thinks the organic livestock system, focused on producing quality feed from grassland, has much to recommend it.

“It’s really tough to farm organically and anyone who is doing it successfully is an exceedingly good farmer,” he says. But he also thinks people can be tempted into organic farming by the concept of a greener lifestyle, and believes groups such as the Soil Association should be more direct in warning of problems that can arise. He highlights the fact that he used the same antibiotics and vaccines as he would have done without organic certification, the difference being that organic farmers need a vet to prescribe. He also believes that the rule allowing organic farmers to use non-organic straw for bedding is flawed, since there is nothing to stop the animals from eating it.

Neither the government nor the Soil Association collects information about why hundreds of farmers have given up their organic status, so the evidence is patchy. I spoke to a handful of farmers from across the UK who have made the change over the past few years. They gave a variety of reasons, from milk prices to soil deterioration to the bureaucracy and costs associated with certification, to lack of local demand for organic produce and the long distances they had to travel to reach markets.

All these factors affected farms’ economic viability, but Michael Johnston, who farms sheep and cattle near Aberdeen, says money wasn’t his only reason for giving up: “It’s not just a question of the subsidies and the premiums. People always say life is complicated, but in this case, it really is.” In Johnston’s case, a reduction in subsidy was a factor, but so was his growing interest in soil biology and climate change, and his conviction that the organic system was not the best way to look after his soil.

Tim Bevan, farm business adviser at the Soil Association, thinks uncertainty about Common Agricultural Policy reform last year made farmers nervous. He says volatile beef prices are an ongoing problem, with farmers moving away from organic when premiums fall.

But he points to growing evidence that organic farms improve biodiversity, and research published last year claiming strong health benefits for organic food, as reasons for optimism. “Conventional farmers are borrowing ideas from organic farmers more and more. There’s a much bigger conversation going on,” he says.

For critics, far from being the solution to organic farming’s problem, such dilution and diffusion of organic principles is part of the problem. Last year’s letter of resignation to the Soil Association from trustees Joanna Blythman, Lynda Brown, Pat Thomas and Andrew Whitley, claimed “the O-word” was increasingly being replaced by a softer, lifestyle-oriented, healthy-eating message. They objected to the use of the long-standing organic slogan, “Food you can trust,” by the non-organic Food for Life Catering Mark.

But do they believe this approach is to blame for the fall in organic farmer numbers? Blythman, a campaigner and writer, says she wouldn’t go that far, but that lowered morale in the sector could be linked to its changed message.

“Organic farmers and growers look to the Soil Association to be a plucky champion, and if it hasn’t played that role well, that could be one reason we are seeing a lack of confidence,” she says. “They pay to be certified, there’s an annual charge, and I wouldn’t be surprised if some of them thought, ‘I’ve got a following now, but I’m still paying this money, what is it doing for me?’ Consumers and farmers want the Soil Association to be an articulate mouthpiece for a coherent alternative to corporate agriculture, and if it has lost sight of that in recent years, despite good intentions, then the pigeons may be coming home to roost.”

But thankfully for the organic consumers who have bucked the trend of declining grocery sales – leading to strong growth in vegetable box schemes, and online retail, particularly in dairy produce, eggs and poultry – the farm traffic is not all one way. At Cwrt Henllys Farm in Cwmbran, near Newport in south Wales, Chris and Ceri Morgan are awaiting the arrival from Scotland of 30 shorthorn yearling heifers and a bull with which they will produce a new generation of organic cattle. On the land farmed by Chris’s father and grandfather, and following a five-year hiatus when the farm was rented out following an inheritance dispute with his father’s ex-wife, Chris is reinventing himself.

“It’s not just the land you’ve got to convert, it’s yourself,” he tells me. “You’ve got to totally change the way you farm. If you can make the soil work for you and keep costs down, you should be able to produce a high-end product at a reasonable cost.”

Originally inspired to change his thinking by Rebecca Hosking’s film A Farm for the Future, Morgan has been studying permaculture, and reading up on soil biology. Now he is ready to try his ideas out. He has replanted wildlife-friendly hedges that were ripped out by his father, and spent the past month digging a large pond that will facilitate a new technique for grazing his cattle.

The morning I visited, he had spotted a combine harvester online for sale, which might do for the corn he will need to feed the hens. He plans to reseed the fields with diverse species of grass. Restoration of the farmhouse and garden is a work in progress, while the family lives in a bungalow across the road. They have just been on a trip to London, investigating farmers’ markets, though it will be three years before they have anything to sell. Morgan wants to future-proof the farm for his sons to inherit, and is looking into putting solar panels on the roof. Ceri talks about self-sufficiency and the 1970s sitcom The Good Life, and serves homemade cake. Come back in 10 years, Chris says. “The idea is that when you walk across the fields, the wildlife, and the insects, lift up as a vision in front of you.” He adds that the birds might take a bit longer than that.

Can they make it work? At the last count 3,740 organic UK farms, mainly concentrated in southwest England and Wales, still do. Some are highly successful. But for the moment at least, the Morgans are going against the herd.