Ohio State University Extension Bulletin

Agronomic Crops Team On-Farm Research Projects 2000

Special Circular 179-01


Roundup Ready Soybean Population Study - Van Wert

Andy Kleinschmidt, Extension Agriculture and Natural Resources Agent
Ed Lentz, Extension Northwest District Agronomist
Gary Prill, Farm Focus/Research Coordinator

Objective

To evaluate the yield response of Roundup Ready soybeans to different seeding rates in order to reduce seed costs by finding an optimum seeding rate.

Background


Cooperator: Marsh Foundation/
Farm Focus
County: Van Wert
Nearest Town: Van Wert
Soil Type: Hoytville silty clay loam
Drainage: Tile (system unknown)
Previous Crop: Corn
Tillage: No-till drilled
Fertilizer: 30 lbs./A 0-0-60 fall applied
Soil Test: pH 6.4, P 88 ppm, K 166 ppm
 
Herbicide: BURNDOWN - Touchdown
5 (2 pt./A) + AMS (3 lbs./A)
POST - Touchdown 5
(2 pt./A) + AMS (3.4 lbs./A)
Variety: Seed Consultants SC9320RR
(treated)
Seeding Rates: See Methods
Row Width: 7.5 inches
Planting Date: May 17, 2000
Harvest Date: October 3, 2000


Methods

This study was conducted using three replications of three different seeding rates (110,000, 165,000, and 220,000 seeds per acre) in a complete randomized block design. All plots were planted using a John Deere 750 no-till drill calibrated with the same seed used in the treatments. Plot size was 28.75 feet wide by 1,030 feet long. Population counts were taken at three locations in each plot using a 17.5-feet distance and counting the rows on both sides of the measure. Yields were taken at harvest using a calibrated weigh wagon, with all yields being adjusted to 13% moisture.

Results


Treatment Harvest Population Yield

(seeds/A) (plants/A) (bushels/A)
110,000 79,900 a 61.5 a
165,000 127,000 b 63.2 ab
220,000 145,800 b 65.0 b

LSD (P=0.05)
CV (<15%=credible) 10.1% 1.7%
26,800 2.4

Means with the same letter are not significantly different at P=0.05


Summary

The data from this year show that the two higher seeding rate treatments had a statistically significant yield increase over the lowest rate treatment. This is the second year for the study at this location. Results from both years would indicate that higher seeding rates provide a statistically significant yield increase. However, this yield increase may not cover the cost of the additional Roundup Ready seed used at these higher rates.

Even with the drill calibrated for the specific seed used in the experiment, it is evident that large variations in final stand counts will be experienced when using a drill for seeding soybeans. It is also interesting to note the large difference between seeding rates and the harvest population stand counts. This difference was present in almost all of the research plots at Farm Focus this year. This most likely can be attributed to the cool wet conditions in the spring that delayed planting and emergence, and to the reduced seed quality this past year.

For additional information, contact:

Andy Kleinschmidt Gary Prill Ed Lentz
Agriculture and Farm Focus/Research District Agronomist
Natural Resources Agent Coordinator OSU Extension,
OSU Extension, Van Wert County OSU Extension, Van Wert County Northwest District
1055 S. Washington Street 1055 S. Washington Street 952 Lima Ave., Box C
Van Wert, OH 45891 Van Wert, OH 45891 Findlay, OH 45840
419-238-1214 419-238-1214 419-422-6106
kleinschmidt.5@osu.edu prill.1@osu.edu lentz.38@osu.edu


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