Aerial imagery for agriculture is fast becoming a standard practice for farmers practicing what's now called 'precision agriculture.'
MapSavvy is an affordable web map service from OnTerra Systems that provides aerial and satellite imagery from Google Maps, Bing Maps, and HERE Technologies — accessible through standard WMS and WMTS connections in the GIS and CAD software you already use, for $999 per year for up to 40,000 images per year.
For related reading, see aerial imagery for business and scientific research. To try the service, start a free 14-day trial or purchase MapSavvy.