The beetroot in Tesco looked the same: small, peeled and purple. Yet the organic pack was £1 and the other 67p. More of the organic packs – produced without chemical fertilisers and pesticides – had been left on the shelf. Perhaps unsurprisingly, many shoppers have decided it's not worth paying more for chemical-free food while times are hard and organic sales have slumped since 2008. To revive the £1.8bn movement, the Organic Trade Board has begun a £2m advertising campaign, "Why I Love Organic", in magazines such as OK! and Heat. Should shoppers be swayed by its claims about naturalness, taste and animal welfare?
Although supporters say buying organic fruit and veg seasonally and direct from farmers can be cost-effective, prices in supermarkets are often at least 50 per cent more. As far as taste goes, most shoppers would struggle to tell the difference between organic and conventional produce of the same variety.
The style sometimes matters: small artisanal producers make organic food to a high standard. Vegetable box schemes such as Abel and Cole and Riverford select varieties for taste rather than perishability and deliver from field to front door in a few days. Organic food often is tastier, but not necessarily because it is organic.
Health is more complex. Two years ago, the Food Standards Agency concluded there was "no good evidence consumption of organic food was beneficial to health in relation to nutrient content". This week, a team at Newcastle University suggested that organic milk had more beneficial fatty acids than conventional milk – again, the differences may be too small to be significant.
Organic food, though, has fewer pesticide traces. In its latest report, the Government's Pesticide Residues Committee found 23 of 349 samples of foods such as milk and peaches exceeded permitted levels. That's 6.5 per cent, or one in every 15. Unpermitted levels are not necessarily unsafe, but some academics are concerned by the cumulative effect of low doses of insecticides, particularly on pregnant women and infants.
Health may be contentious but there is no doubt organically-farmed animals have better lives than their factory-farmed counterparts. The Soil Association bans fast-growing breeds of chickens that develop leg problems. Instead, its chickens have twice the lifespan and space, while organic pigs can roam outdoors most of the time, with their tails, because docking is banned.
Intensively farmed, heavily sprayed prairies have been a disaster for nature. Over the past 50 years, most of England's hedgerows have been ripped out; more than half of farmland birds such as skylarks, lapwings and linnets have disappeared; and numbers of farmland butterflies, which make up most of the UK's 57 species, have plummeted by 42 per cent in the past 20 years.
As the RSPB points out, nearly all studies show that organic farms have more wildlife. But does this abundance justify their lower yields? Researchers at Leeds University reported last year that organic farms typically had 12 per cent more plants and animals than similar conventional farms, but grew 55 per cent fewer crops. This meant they could not be promoted as the best method of agriculture, said Professor Tim Benton, who led the research.
Certainly, organic yields are lower than conventional ones, though organic farmers dispute the 55 per cent figure. Three years ago, the University of Michigan concluded that organic farming could produce enough food to feed the current world population "and potentially an even larger population" without using more land.
Given that one third of food in Britain is wasted, and the national diet consists of too much meat and too little fresh produce, the wider adoption of a less resource-intensive, healthier diet could make up for any loss in yields from organic farming. There is already enough food in the world; poverty, not lack of food, causes one billion people to be undernourished. One billion are overweight.
Overall, organic is likely to be a little healthier and tastier than conventional. At every checkout shoppers vote for how they want farm animals to be treated, how the landscape should look, whether wildlife should thrive or disappear. Buying organic is a vote for family farms and hedgerows, for fields and wildflowers and for birds, bees and butterflies. Romantic maybe, but right.