"We have found pigs grow faster on beans than on soya — but it's like drawing teeth stopping nutritionists using the bloody stuff.

"50 per cent of our feed is made up of wheat, barley and beans, and oilseed rape at 25 kilos a tonne.

"Our top priority is to reduce the risk of making a loss so some years ago we sold sows and bought land, so that now we grow all the cereals that we consume as a pig producer.

"I can grow beans for about £80 a tonne, compared to about £200 to buy them in and that compares very favourably with soya at around £400 a tonne. We've been up to 30 per cent beans and those have been our fastest growing pigs.

"We grow wheat-wheat-barley-beans and in a good year expect 4 tonnes from the first wheats, 3 tonnes from the second, 3 tonnes of barley, and 2 tonnes of beans — or 3 tonnes average across the rotation.

"A sow with all progeny needs 6 tonnes, so we allow for two acres per sow. What comes out of the back end of the pig provides enough phosphate and potash for two acres, if you grow beans in the rotation, because they don't need anything.

"But the pigs don't give you enough nitrogen, so the beans make an important contribution, because they mean we don't need nitrogen on 25 per cent of our land, and that's a big help.

"The pigs may not produce enough nitrogen, but they do produce plenty of ammonia, and if you collect that and add sulphuric acid, you get ammonium sulphate. We're trying that now to see if it works."