There are now 50 farms which open their gates to visitors, and the association hopes to make it 100 within two years.
"We are trying to reconnect people with the sources of their food. Our aim is to have an organic farm within easy reach of every school in the country," says Rupert Aker, an education officer at the association. Three of its farms - in Somerset, Pembrokeshire and Cumbria - offer residential visits lasting three or four days. Clynfyw in Pembrokeshire and Magdallen near Chard can accommodate up to 30 people, while Low Luckens in Cumbria can put up 16.
At Low Luckens, near the epicentre of the recent foot and mouth outbreak, children can see what happens to organic meat - and even make their own healthy burgers to take home with them.
The farms vary in size from the seven-acre smallholding, Primrose Organic Centre, between Hay-on-Wye and Brecon, to the 1,000-acre Abbey Home Farm near Cirencester.
At Primrose , a few acres of vegetables and a "keyhole" garden with raised beds mean pupils can examine the plants at eye-level. The larger Abbey Home Farm produces cereals, beef, lamb and milk. Its garden produces more than 200 varieties of vegetables, herbs, soft fruit and cut flowers. In the Green Room, just opened, pupils can learn more about food production, preparation and the environment. The Room was built using green oak from the farm , and is heated by solar panels and woodburners.
"What the children really want to do is to touch, smell and see - seeing livestock really engages them," says Rupert Akers. "At some farms we create a bit of an event, by having four or five schools there on at the same time enjoying an organic discovery day," he says. "The key thing is to have enough people around to get the children to concentrate and channel their energy usefully."
Along the way, they learn about the production of organic food. "And, yes," says Rupert Akers, "we have genuinely had children claiming that milk came from a bottle or the supermarket."
Bernard Adams It costs from nothing to pound;5 to visit one of the farms on the Soil Association scheme. The association can provide bursaries to help needy schools with the cost of transport.For further information about farm visits or how to obtain Soil Association resource materials, contact Colin Esrich, education officer on 0117 914 2440; email: email@example.com; www.soilassociation.orgeducation