Switchgrass features 13 miles of hiking trails near Wilson, KS.
From I-70, take exit 206 north about 5.5 miles to Wilson State Park. Go west on Shoreline road across the bridge then turn into Wilson State Park at the sign. There is an entrance fee for the state park, its less then $5/vehicle (varies with season). Continue into state park to Switchgrass Campground.
http://www.tripleblaze.com/trail.php?c=3&i=1634