The report estimates diesel costs for planting corn, soybeans, wheat, cotton, and rice increased 63.2 percent nationwide between the 2025 and 2026 planting seasons, driven by higher fuel prices. Top 20 states with the largest increases in planting diesel costsThe congressional committee, whose Democratic minority staff produced the analysis, said higher diesel prices followed the Trump administration’s military strikes on Iran. Illinois recorded the nation’s largest overall increase in planting diesel costs, at an estimated $163.2 million, followed by Iowa ($151.1 million) and Minnesota ($101.7 million). The committee also estimated how much more farmers paid to refill common pieces of equipment at peak diesel prices during the 2026 planting season. Nationally, compared with the same period in 2025, it estimated farmers paid an average of:$1,538 more to refill a typical 750-gallon on-farm fuel tank.