[Gordonjcp]

You've got it backwards. Farmers want to make more money from what they grow, but supermarkets push the price down. Look at milk, for example - big supermarket chains pay farmers just barely above cost for milk at the farm gate and sell it at barely above cost as a kind of loss leader. What option do farmers have but to sell it, make fuck all off it, and try to work as cost-effectively as possible?

If you buy food from the supermarket, you're contributing to the decline of the planet's ecology, because it's the profitable thing to do.

[kragen]

This is a fully general criticism of competitive markets and is not limited to supermarkets. It applies with equal force to farmers, grain elevators, shippers, fertilizer makers, and (as you do note) the supermarkets' customers. You might argue that it applies with greater force to Monsanto (because they have government-granted monopolies on particular seeds) and to supermarket consumers (because they are not buying supplies for a product they are selling and can therefore choose to pay more).