Survey reports use of custom work and range of prices paid. Data is summarized by nine crop reporting distrcits. The average rate, most frequent rate, and the range of rates are given for 38 different kinds of custom work.
Howell, H. B. and Hill, Harold
"Custom Rates Paid by Iowa Farmers,"
Iowa Farm Science: Vol. 21
, Article 4.
Available at: https://lib.dr.iastate.edu/farmscience/vol21/iss1/4