Sir: Organic fertiliser doesn't have to be smelly (letters, 7 October). Animal manure which has been processed in a biogas digester loses its smell, gives off useful energy and loses nothing of its fertilising ability - in fact it is improved. Every time I pass a smelly pig farm I think the smell represents profit the farmer is missing. Perhaps there should be a tax on smell.
E G MATTHEWS
Wimborne, DorsetReuse content