Oklahoma State University

Contact Info

Josh Lofton, Assistant Professor
Cropping Systems Specialist
Oklahoma State University
376 AG Hall
Stillwater, OK 74078
Phone: 405-744-3389
FAX Number: 405-744-0354






Page Title

Soybean Planting Date Test



Rick Kochenower, Panhandle Research and Extension Center, Goodwell; Ron Sholar, Dept. of Plant and Soil Sciences. Soybean Research at OSU 1999. p. 20. OSU/DASNR/OAES/OCES. P-976

Soybeans are a new crop of increasing interest with producers in the Oklahoma panhandle. Previous soybean research concentrated mostly on variety selection through variety trials at Oklahoma Panhandle Research and Extension Center (OPREC,) Goodwell, OK. Research was started in 1999 to determine optimum planting- date for irrigated soybeans for the region. Plots were 10 feet by 20 feet planted with a 5-foot drill at 5 dates (Table 1). Asgrow AG4602RR was planted at a rate of 160,000 seeds per acre. Plots were harvested on October 18, with a Massey- Ferguson 8 plot combine to determine yield. The month of May was the optimum planting period. The highest yields were realized on plots planted on May 15 (Table1).

Table 11. Irrigated Soybean Planting Date Test, OPREC, Goodwell, OK.

Planting Date Yield bu/acrecre Test wt Lb/bu
May 5 60.5 54.0
May 15 72.5 54.8
June 1 60.1 55.3
June 15 45.7 53.6
July 2 33.9 51.3
Mean 54.5 53.8
LSD(0.05%) 8.6 2.3
CV 10.3 2.8

Planting during the first two weeks of June also produced acceptable yields, The June 15 planting date resulted in a yield of 45.7 bu/acre. When planting after this date soybean plants do not have sufficient growth prior to the start of flowering to produce a yield comparable with the earlier planting dates. The soybean is a photoperiod sensitive plant, so when the length of sunlight changes flowering is initiated. Additional research will be conducted to determine if maturity group selection will have an effect on yields at different planting dates.



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