Steve Prochaska, Extension Agriculture and Natural Resources Agent
It has been theorized that soybeans would benefit from supplemental nitrogen applications during early reproductive growth states. The objective of this study was to examine soybean yield response to supplemental nitrogen applied during early reproductive stages.
| Test Site: | Ohio State University | Soil Test: | pH 7.3 |
| Unger Farm | P 16 ppm | ||
| County of Site: | Crawford | K 88 ppm | |
| Soil Type: | Pewamo | Fertilizer: | 27-69-60 applied fall 1997 |
| Drainage: | Systematic | Urea spread @49.5 lbs | |
| Irrigation: | None | actual N 7/6/98 | |
| Tillage: | Field cultivated twice in spring | Herbicide: | Roundup Ultra 1 qt |
| Previous Crop: | Pumpkins | Seeding Rate: | 63 lbs/acre |
| Soybean Hybrid: | Pioneer 9333 | Planting Date: | 5/14/98 |
| Harvest Date: | 9/25/98 | ||
Urea @ 107.5 lbs/acre was applied in 30' swaths (used only one boom) with Ag Chem air machine in three random strips across soybeans at growth stage R1.2. Rainfall occurred July 7, 1998, thus lessening nitrogen volatilization losses. The center 22 feet of the strip plots were harvested to measure treatment effect. Individual harvested plot size was 0.17 acre. Experiment design was completely randomized with three replications for each treatment.
| Treatment | Yield (bu/acre) |
|---|---|
| Urea | 63.07 |
| No Urea | 65.93 |
| F = 2.06 Not significant at P = 0.05 CV = 3.8% | |
Each bushel of soybeans contains from 3.0 to 3.5 pounds of nitrogen. Thus, a 60-bushel-per-acre yield of soybeans requires 180 to 210 pounds of nitrogen. Soybeans, being legumes, have a symbiotic relationship with Rhizobium bacteria. These bacteria have the ability to fix 200 pounds of nitrogen or more per acre. However, there are reproductive stages in the growth of soybeans where nitrogen deficiency may occur. In this study, there was no significant difference between treatments. These results are consistent with previous studies on this topic.
For additional information, contact:
Dr. Steve Prochaska
Ohio State University Extension, Crawford County
117 East Mansfield Street
Bucyrus, OH 44820
419-562-8731
prochaska.1@osu.edu