agricultural vehicles, which has led to increased risks of soil compaction. Hence, farmers benefit from machinery
with higher capacity but may suffer from decreased yields caused by compaction. Compaction may result in
further environmental costs to society. We present a framework that relates the machinery capacity to soil
compaction and its impacts on crop yields and environmental disservices, and associated revenues and costs for
farmers and society. We combined simulations using a soil compaction model and a soil-crop model with simple
economic analyses. We applied the framework to a case study of cereal production in Sweden, to derive the
optimal combine harvester size that maximizes the farmer’s private profit and the societal net benefit, respectively.
Increased machinery size decreased harvesting costs, but also reduced simulated crop yields and thus crop
revenue as a result of soil compaction. Furthermore, in the model simulations, compaction also increased surface
run-off, nitrogen leaching and greenhouse gas emissions. Intermediate machinery size maximized the farmer’s
net revenue. Net benefits for society were highest for the lowest possible compaction level, due to the considerable
external costs from soil compaction. We show that the optimal machinery size and thus compaction level
for maximum farmer revenue would decrease if either producer prices were higher, harvesting costs savings from
larger machinery were smaller, or if farmers were charged for (part of the) environmental costs.