but which is the most ecologically sound choice?
It's very hard to tell. The BBC tried to sum it up in this http://news.bbc.co.uk/1/hi/uk/4314507.stm
which refers to this article on food miles
http://news.bbc.co.uk/1/hi/sci/tech/4312591.stm
And this report makes it all clear - NOT http://www.newscientist.com/article.ns?id=dn7092
My wife's got a book at home about "chemical calories" which has a brilliant table about what fruit and veg. is actually affected by insecticides and fungicides. It has allowed us to only go organic when we need to, not just try to buy organic always.
If the crops are sprayed early in their growing cycle the spray is not likely to leave a residue in the end produce, but the crop cannot be called organic, so buying from the producer will allow you to ask the correct questions.
There are farm shops that I pass in my normal travelling so visiting them is not costing extra pollution from me and they major on local produce, with the bonus that some of the produce is organic.
I've been toying with the idea of buying an electric car and powering it from solar panels for a few years now. I nearly bought an electric Renault Kangoo from France a couple of years ago, but the UK dealers refused to service it and I couldn't be bothered enough to insist! I might yet build my own, but then that would get in the way of caving time!
Farming and produce really seems to be a hot topic!