Previously published research reported a “synergistic effect” of corn (Zea mays L.) on winter wheat (Triticum aestivum L.) and proso millet (Panicum miliaceum L.) water use efficiency (WUE) when corn (C) was the preceding crop for dryland cropping systems in the central Great Plains, i.e., less water was required to grow a unit of wheat (W) or proso millet (M) when corn was the preceding crop. ...