The slump in organic sales at the supermarkets has a prompted a sharp drop in the number of farmers converting to organic production, according to DEFRA figures.

The land area under conversion has fallen by two thirds since 2007, the department’s statistics show.

Soil Association price data shows sales fell by almost 6% in 2010 from £1.8bn in 2009 to £1.7bn last year. The market has lost almost £0.5bn a year since the record sales of £2.1bn in 2008.

The decline in value of the market is also shown in the area of land already converted as farmers return to conventional cropping. The UK total organic land area fell by more than 22,000ha or 3% between 2009 and 2010 to 718,000ha.

For the second year running, the number of organic producers decreased. A fall of 4% to 7,300 at the end of 2010 matches the reduction in the total area of organic land.

All the UK’s regions declined with Northern Ireland experiencing the largest percentage drop of 14%, and the North West showing the largest percentage drop in England for the second year running of 5%.

Land sown with organic cereals declined by 5% to 57,000ha which DEFRA attributed to falling organic grain prices.

Temporary and permanent pasture land continue to make up the majority (84%) of organic land and that showed little change between 2009 and 2010, the DEFRA statistics show.

Temporary pasture declined by just 1% to 125,000ha and permanent pasture fell by 3% to 479,000ha.

But the numbers of organic cattle and sheep have increased. The number of organic cattle rose by 6% to 350,000 as sales of organic beef rose in 2010, even though prices of organic dairy produce levelled off in 2010.

Sheep numbers were up by 11% to 981,000 in the 12 months to 2010 as the supply of lambs was boosted by new entrants.