Double Crop Soybean in the North Central US.

The total double crop acreage of the Midwestern U.S. (4.4 million ha) is second only to the Southeastern U.S. (6.7 million ha). Many states or portions of them are included in the “Midwest” estimate calculated from the USDA-ERS. Missouri, Illinois, Indiana, Ohio, Kentucky, and a portion of Tennessee were included in the “Midwest” estimate. The vast majority of the successful double crop production within these states occur south of 39° N parallel (i.e., length of growing season for double crop soybean). Double soybean production in the Midwest represents only 1.6% of the total cropland acreage in this region with the greatest proportion from Kentucky (30%) followed by Missouri (10%), Illinois (5%), Indiana (3%), and Ohio (1%). Small grain production, namely winter wheat, is prevalent in many other areas of the North Central region of the US, but the success rate of double crop soybean production is low due to the shorter growing season as acreage is north of the 39° N parallel. Later harvest of small grains (thereby, later plantings of double crop soybean) and the earlier fall freezes are the main constraints. Multi-crop systems in this region have shown some promise when altering maturity of the small grain or even the type of winter crop (e.g., barley, canola), harvest timings, and maturity of the soybean. The concept of relay cropping or intercropping soybean into existing stands of small grains has shown some success in producing two crops (winter wheat and soybean) in the same season in these northern regions, but require greater level of management. We will discuss the past production practices and current research and management efforts for advancing double crop soybean. We will also share some of the new systems/technology that may help to push double crop or relay soybean further north.