Diversified, low external input (LEI) cropping systems offer a possible approach for maintaining adequate productivity and profitability while reducing use of agrichemicals and fossil energy. Over the study period (2003 to 2011), mineral N fertilizer use was 80% and 86% lower in the three-year and fouryear LEI systems, respectively, than in the two-year conventional system. Similarly, herbicide use was reduced by 86% and 89%, respectively, in the three-year and four-year LEI systems. Fossil energy inputs were on average 49% lower in the LEI systems than in the conventional system. Corn yields were on average 4% higher and soybean yields were 9% higher in the LEI systems as compared with the conventional system, and matched or exceeded average yields on commercial farms in Boone County.