Here’s the full report on farmland returns from Iowa State University.
The report includes estimates of the average returns from owning farmland since 1970. Annual returns are in two forms: cash returns and change in market value. Total return is the sum of these two. The source of data for cash rents and land values is the Economic Research Service (USDA) data series for whole farm rents and value, not data from ISU Extension, which refers to rental rates for corn/soybean land only.