In April the Mohawk pushes fog up over the Rotterdam flats and the grass comes on all at once, greener than it has any right to be. Erb Landscaping and Lawn care LLC meets that first rush with mowing, edging and trimming, plus the spring cleanup that hauls off everything winter left lying around. River-valley soil grows a heavy lawn, so holding a neat height through May and June is a matter of showing up on time, week after week. Later the work turns to keeping that line, and then to the fall cleanup, when the maples let go in a single windy stretch. A yard cut clean on a cool Schenectady County morning is a small and reliable pleasure.