By late August the open fields around Duanesburg have gone the color of a struck match, timothy and goldenrod leaning all one way in the wind that crosses the plateau. Amberfield Lawn Services LLC keeps the yards inside that landscape green and tidy — weekly mowing, trimming and edging, with cleanups in spring and again after the leaves come down. Up here the growing season is short and honest, so the weeks that are good for grass get used completely. A lawn held to a straight border against a hayfield draws a small deliberate line between the kept and the wild, and it looks right when it is done well. That contrast is worth the effort every single week.