Monday, November 13, 2006

Determining Profitable Soybean Seeding Rates in Kansas.

Michael Epler1, Scott Staggenborg1, and Larry Maddux2. (1) Kansas State University, 2004 Throckmorton Plant Sci. Ctr, Manhattan, KS 66506, United States of America, (2) Kansas St. Univ., 9748 NW 66th, Silver Lake, KS 66539

Soybean (Glycine max) yield is responsive to changes in plant population under dryland conditions most years in Kansas.  This study was conducted to evaluate soybean yield response to plant density in narrow row-drilled systems (19 cm), and to determine a minimum seeding rate to apply without decreasing yield.  The effects of plant population on yield, and yield components in narrow row soybeans were studied in 2005 at Manhattan, KS, Rossville, KS, and Ottawa, KS.  The data for the three locations were evaluated using a linear plateau and at all three locations, yields increased from as population increased up to a plateau at approximately 200,000 plants ha-1.  The two yield components responsible for yield failing to continually increase were pods per plant and pods ha-1.  As plant population increased, pods per plant were affected negatively, and decreased steadily however, yield was not reduced by the loss of pods. This was due to a constant increase of pods ha-1 as plant population was increased.  A plant population of 200,000 plants ha-1, which is much lower than the recommended soybean population of about 375,000 plants ha-1, did not adversely affect yield and may be useful in decreasing input costs in dryland soybean production.