How does soil erosion affect crop yields in North America?
A. Although erosion is widespread, it is difficult to quantify its effect on agricultural productivity and production. Past estimates of production losses to erosion in North America (ranging from $300 million to $27 billion) used simulation models or average values for erosion and crop yields, disregarding differences due to regional variations in soils and climate. Den Biggelaar et al. estimated production losses and economic impacts of erosion for corn, wheat, soybeans, and cotton using soil-based extrapolations from existing erosion-productivity studies in the soil science literature. Accounting for soil- and crop-specific erosion rates and yield impacts, the estimated value of erosion-induced production losses for these crops decreases from $83 million (using national-average erosion rates) to $56 million. This estimate does not include the extra costs for fertilizers, irrigation, and machinery, and any off-farm effects of erosion. While onsite productivity impacts are relatively
