BRIAN FANE needs to take some additional factors into account when talking about organic food (Letters, August 15).

Papers published in the Journal of Agriculture and Food Chemistry (Vol 55, No 15, 2007) show a marked difference in nutritional values between organically and conventionally grown tomatoes.

But neither these tests, nor the tests published by the Food Standards Agency recently, which purport to show no differences, and which had wide publicity, tell us anything about the years that the soil was treated organically since conversion.

And that is the nub of the matter. In only two years, I am not surprised there is little difference, but this is the period the Soil Association certifies crops as organic.

I have been questioning its standards for some years and it tells me this is for the sake of farmers who cannot afford to wait longer. So consumers in our ignorance lose out.

But never mind. As oil becomes scarcer over 20 years or so, chemical fertilisers, made partly from oil, will become more expensive and farmers will return to utilising and recycling their own byproducts.

And the soil, rich in untapped minerals, will once again have a chance to become rich in earthworms and other soil organisms which help to make minerals available to plants.

Proper rotation with nitrogen binding legumes makes use of the nitrogen in the air and then makes it available to the next crop. That’s organic farming eventually, if only by the back door.

Hans Lobstein Marine Parade, Brighton