Growing evidence

Prof Trewavas rightly observes the soil-fertility building programmes undertaken on organic farms. He incorrectly implies that this is an unproductive period.

Here at Peelham we grow  cereals and livestock as well as legumes which are key to fixing free nitrogen from the atmosphere. We operate a farming  system which hinges on recycling of nutrients from animals to maintain soil fertility.

The fertility-building period is highly productive, growing silage and lambs, and takes place using free nitrogen.

The food produced from our farm has increased since we changed to a chemical-free method of farming.

Our soils now have higher organic matter, making our fields easier to cultivate, better at retaining water in a dry year and freer draining in a wet year.

While I agree that chemical inputs can increase yields, this difference can be as little as 25 per cent, demonstrating that the productivity generated by those finite artificial chemicals is marginal and expensive.

One kilogramme of artificial nitrogen costs 85p, the return can be £2.80 but the true cost can be between £4 and £20 in terms of the cost of environmental impact.

There is growing evidence indicating that fungicides are now causing reproductive disorders and stunted growth in earthworms, which are so important to soil fertility.

Further research demonstrates that glyphosate, a commonly used herbicide, is linked with coeliac disease in humans and  digestive problems in animals.

Sustainable food production is a learning curve for all farmers. We are encouraged by the results of our choice to farm without  reliance on artificial fertilisers and pesticides.

Chris Walton

Peelham

Foulden, Berwickshire