Extreme Agriculture: What Do Maximum Yields Mean?.

The entire soybean community was astounded when Mr. Kip Cullers, a farmer in SW Missouri, reported in verified yield contests grain yields in 2006 of 9.4 Mg/ha (139 bu/ac) and in 2007 of 10.4 Mg/ha (155 bu/ac). The previous record yield of 7.9 Mg/ha (118 bu/ac) was recorded in 1983 by Dr. R.L. Flannery at Rutgers University. Soybean yields greater than 8 Mg/ha are beyond what are considered possible in most theoretical models. Utilization and/or availability of light, water, and nutrients (particularly N) are viewed as limiting crop yield potential in theoretical models. Environmental data from 2006 and 2007 will be used in a crop simulation model to characterize the combination of resources necessary to achieve grain yields in excess of 10 Mg/ha. Measurements in 2008 are being made of radiation use efficiency, crop mass yield, and harvest index from Mr. Culler's farm, and these measurements will be compared with modeled parameters required to achieve these extraordinary yields.