http://farmdocdaily.illinois.edu/2018/02/estimated-2017-arc-co-payments.html
Fewer counties are receiving 2017 payments than in 2016 (see farmdoc daily, October 6, 2017). ARC-CO uses five-year Olympic averages in calculating benchmark prices and benchmark yields. By design, benchmark prices will decline in periods of low MYA prices. As a result, benchmark prices used to set guarantees for corn have been coming down, resulting in fewer payments. The 2016 benchmark price was $4.79 compared to a $3.95 price in 2017. Moreover, yields were above average over much of the United States in 2017.
Source: Schnitkey, G., J. Coppess, C. Zulauf, and N. Paulson. "Estimated 2017 ARC-CO Payments." farmdoc daily (8):34, Department of Agricultural and Consumer Economics, University of Illinois at Urbana-Champaign, February 27, 2018.