About 9% of the total soybean acreage and about 50% of the total corn acreage in Nebraska was irrigated at least once during the growing season in 1975. The 1975 state averages for irrigated soybeans and irrigated corn were 2220 and 7605 kg/ha respectively. Obviously, this yield differential (in relation to the price and production cost differentials) accounts for the reason most farmers utilize their irrigated acreage for corn rather than soybeans.
Specht, J. E. and Williams, J. H.
"Research Notes: Evaluation of some soybean isolines in irrigation culture,"
Soybean Genetics Newsletter: Vol. 4
, Article 22.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol4/iss1/22