Ed Lentz, Extension District Specialist, Agronomy
Alan Sundermeier, Extension Agent, Agriculture and Natural Resources
To evaluate the effects of seeding rate on the yield of late-planted soybeans.
| Cooperator: | OARDC Northwestern | Fertilizer: | 100 lbs. 0-46-0 |
| Branch | 150 lbs. 0-0-60 | ||
| County: | Wood | Planting Date: | June 17, 2002 |
| Nearest Town: | Hoytville | Seeding Rate: | See Methods |
| Drainage: | Systematically tiled | Row Width: | 7.5-inch |
| Soil type: | Hoytville clay | Herbicides: | |
| Tillage: | Disk | PRE: | 3.4 oz/A Canopy SP |
| Previous Crop: | Corn | 16 oz/A 2, 4-D Ester | |
| Variety: | Pioneer 93B01 | POST: | 26 oz/A Roundup Ultra |
| Soil test: | pH 6.5, P 104 ppm | Max + AMS | |
| K 208 ppm | Harvest Date: | October 9, 2002 |
Experimental design was a randomized complete block with four treatments replicated four times. Treatments were four seeding rates — 150,000; 200,000; 250,000; and 300,000 seeds/A. A Great Plains No-Till Drill was used for planting. Drill was calibrated by using a seed counter before planting. Plots were 10 feet wide and 74 feet long. The center 11 rows of each plot were harvested for grain yield. A plot combine scale and moisture sensor was used to estimate grain weight and moisture. Yield was adjusted to 13% moisture. Harvest population was estimated by counting plants from four adjacent rows for 6.5 feet from three areas of each plot.
Table 1. The Soybean Grain Yield, Harvest Moisture, and Harvest Population.a
| Seeding | Grain | Harvest | Harvest |
| Rate | Yield | Moisture | Population |
| (seeds/A) | (bu/A) | (%) | (plants/A) |
| 300,000 | 47.2 a | 13.7 | 272,082 a |
| 250,000 | 45.8 a | 13.2 | 230,533 b |
| 200,000 | 43.7 a | 12.9 | 169,772 c |
| 150,000 | 37.9 b | 12.2 | 124,872 d |
| LSD (0.05) | 5.7 | NS | 12,873 |
| F-test | 5.3 | <1 | 261 |
| a Means followed by the same letter in a column are not statistically different | |||
Grain yields were similar for seeding rates 200,000 seeds/A and above. The 150,000 treatment had significantly lower yields than other treatments. Harvest moisture was not affected by seeding rate. Significant separation was observed for harvest populations among treatments. Conditions were good for stand establishment as evidenced by the stand being 88% of the target-seeding rate across treatments.
Higher seeding rates are generally recommended for later plantings. This study would suggest that 200,000 seeds/A would be adequate for optimal yields under good growing conditions for late plantings. Reducing seeding rate 50,000 seeds/A, assuming a 50-lb bag of Roundup Ready Soybeans cost $20, and 3,000 seeds/lb, may save approximately $7/A.
Further studies are required to determine which seeding rate would be adequate for more stressful conditions during emergence.
The authors of this report are grateful for the support provided by the OARDC staff at the Northwestern Branch.
For more information, contact the following individuals:
Ed Lentz
OSU Extension Northwest District
1219 W Main Cross St., Suite 202
Findlay, OH 45840
419-422-6106
lentz.38@osu.edu
Alan Sundermeier
OSU Extension Wood County
440 E Poe Road, Suite 101
Bowling Green, OH 43402
419-354-9050
sundermeier.5@osu.edu