>>The problems I see are polluted hives, polluted air and polluted 
soil.

A fellow beekeeper has been keeping a few hives on farms east of 
here.  He does it for the pollination of crops.  He says, unlike his 
hives in suburbia, the farm hives never build up well in the 
spring/summer and the queens get frequently superceded.  This changes 
in the late summer, after the farmers stopped using chemicals, but 
the colonies don't get strong enough to gather the fall crop in the 
adjacent fields.

Clean hives and pastures are key.

Waldemar  

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