To determine if the timing of spring nitrogen application to wheat influences soybean yield in a modified relay intercropping system.
| Cooperator: | David Brewer |
| County of Site: | Crawford |
| Nearest Town: | Bucyrus |
| Major Soil Type: | Blount |
| Drainage: | Improved |
| Irrigation: | None |
| Tillage: | No-till |
| Previous Crop: | Soybeans |
| Soil Test: | pH 7.2 P 126 lbs/ac K 316 lbs/ac |
| Fall Fertilizer: | 300 lbs/ac 7-28-28 applied before planting |
| Herbicides: | Treatment 1: 0.5 pt 2,4-D applied 4/14/97 |
| Treatment 2: | 1 pt 2,4-D applied 4/19/97 |
| Varieties: | Patterson wheat, Resnick soybeans |
| Planting Dates: | 10/4/96 wheat, 6/20/97 soybean |
| Planting Rates: | 120 lbs/ac wheat, 90 lbs/ac soybean |
| Harvest Dates: | 7/21/97 wheat, 10/21/97 soybean |
Top-dress nitrogen was applied to wheat at two different times. Treatment 1 was a single application of 65 lbs. of 28% N applied on 3/24/97, and treatment 2 was a split application of 65 lbs. 28% N on 3/24/97 plus 60 lbs. of 28% N applied 4/16/97. Individual plot size was 0.35 acre with four replications of each treatment.
| 1997 Modified Relay Intercropping Soybean Yield Data (bu/a) | |||||
|---|---|---|---|---|---|
| Treatment | Rep 1 | Rep 2 | Rep 3 | Rep 4 | Average |
| Single N | 28.6 | 34.8 | 27.8 | 35.1 | 31.6 |
| Split N | 24.7 | 25.5 | 26.1 | 24.5 | 25.2 |
| F value 10.25, significant at .05 level, LSD 4.87 bu/a, CV = 9.92; design was completely randomized | |||||
| MRI Soybean Yield Results (Three-Year Average) | ||
|---|---|---|
| Year | Single N Application | Split N Application |
| 1994 | 41.1 | 40.1 |
| 1995 | 28.9 | 25.2 |
| 1997 | 31.6 | 25.2 |
| 3-Year Average | 33.9 | 30.2 |
| No significant difference between three-year averages of nitrogen treatments. | ||
| 1996 year not analyzed due to severe wheat winter kill. Overall average of all treatments = 32.1 bu/ac. | ||
To address the issues of farm profitability and environmental protection, a modified relay intercropping (MRI) system has been studied. In this system, soybeans are planted into wheat at or past the heading stage of growth. A modified relay intercropping system can effectively utilize farm labor, time, and equipment, while at the same time reducing herbicide usage in the soybean crop. A descriptive study was conducted to measure the effects of variable wheat nitrogen fertilizer rates on soybean yield. The three-year soybean yield over all treatments in the MRI system average was 32.1 bushels per acre. The wheat three-year average over all treatments in the MRI system was 68.9 bushels. See the discussion under "MRI Wheat Nitrogen Research" results for a revenue analysis.
Submitted by:
Dr. Steven Prochaska
Ohio State University Extension - Crawford County
117 East Mansfield Street
Bucyrus, OH 44820
419-562-8731
prochaska.1@osu.edu