<http://schema.org/description>
"Clean air and water, recycling of nutrients, crop pollination, weed and pest suppression: these are just a few of the services provided to us by the ecological systems that function within our agricultural fields."^^<http://www.w3.org/2001/XMLSchema#string>
<http://extension.psu.edu/plants/sustainable/news/2009/08/3ecosystemfieldday>