Author
 |
Heatherly, Larry |
|
Submitted to: Midwest Soybean Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 7/26/2004 Publication Date: 8/8/2004 Citation: Heatherly, L.G. 2004. Midsouthern usa soybean yield trends. Midwest Soybean Conference Proceedings. Des Moines, IA. Aug. 8-9, 2004. Online: http://www.iasoybeans.com/whatnew/msco4/proceedings/midwest.pdf Interpretive Summary: There is concern that USA soybean yields are stagnating. In the midsouthern USA, however, the trend is toward increasing yields. Planting early-maturing varieties (maturity groups III and IV) from late March through late April to avoid drought stress that is common in July and August is the major reason for this increasing yield trend. Research results indicate that yield increases can be as high as 20 bu per acre from nonirrigated plantings made before mid-April vs. later. Technical Abstract: Summer drought stress (high temperatures and low rainfall) in July and August contributes to lower production potential for soybean in the midsouthern USA. Average monthly temperature and pan evaporation increase and rainfall decreases from May through August at these locations. Average soybean yields in the midsouthern USA were low and static from the 1970s through the early 1990s. Since about 1992, they have shown a definite increasing trend. In 2003, the states of Arkansas, Louisiana, Mississippi, and Tennessee produced record high yields. The record yields were attributable to either early planting or greater-than-normal rainfall in July and/or August, depending on the state. Yield data from extremely dry years point out the importance of planting early to avoid the detrimental effects of drought stress. The trend in the midsouthern USA is or should be toward more planting from late March through late April vs. delaying planting until May and June. The use of the combination of early planting and early-maturing varieties allows drought avoidance in a region where the futility of forcing soybean to fill seed during July and August with little rain is proven. |
