MADISON, WI, March 16, 2009 -- Planting soybean on the optimum date produces maximum yield and profit without increasing production costs. Unfortunately, the optimum planting date is hard to indentify, because it varies from year to year, depending on the weather and how much it rains and when it rains.
"Planting date has been a favorite topic of researchers ever since soybean was introduced into the United States, so there is a large database of experiments in the literature. A combined analysis of this database will provide a clearer picture of the average response than any single experiment," explains Dr. Dennis Egli, University of Kentucky, Lexington.
Dr. Egli and colleagues at the University of Kentucky analyzed the combined results of planting date experiments and published their findings in the March-April 2009 issue of the Agronomy Journal.
The scientists analyzed combined results of planting date experiments from the Midwest (NE, ND, IA, IL, IN, and OH), the Upper South (AR, KY, MO, and TN), and the Deep South (AL, FL, GA, LA, MS, and SC). Planting dates varied from mid-April (early April in the Deep South) to July. The experiments included several varieties and several row spacings, but none were irrigated.
In spite of the differences in environmental conditions and varieties from the Midwest to the Deep South, the response of yield to planting date was remarkably consistent across the three regions. Average yield did not change as planting was delayed from mid-April until late May or early June. Thus, there was no evidence that April plantings produced higher yields in any of the three regions. Early April plantings were included in the Deep South and average yields decreased for these ultra-early plantings.
A previous study published in the Agronomy Journal [Vol. 101:131-139 (2009)] concluded that April and early May plantings in Indiana consistent
|Contact: Sara Uttech|
American Society of Agronomy