http://thinkprogress.org/climate/2016/02/03/3744925/maryland-chicken-manure-legislation/

The state’s phosphorous management plan went into effect in June,
and farmers with cropland designated to be the most at risk for runoff are no
longer allowed to apply chicken manure to the land. Each year, the management
plan will add more at-risk cropland to the list, slowly but steadily lessening
the available cropland for manure disposal. At the same time, chicken farming in
Maryland is undergoing a rapid expansion, with some 200 chicken houses slated to
be built on the Delmarva Peninsula this year alone.