Andy Kleinschmidt, Extension Agriculture and Natural Resources Agent
Gary Prill, Extension Associate, Farm Focus/Research Coordinator
To evaluate the yield response of wheat to two different nitrogen topdress rates and the addition of sulfur in a spring topdress application. Farmers typically apply 90 to 100 pounds of nitrogen in a topdress application in the spring and often don’t use previous nitrogen credits. This study will try to determine if a lower rate of topdress will provide the same yields, and if the addition of sulfur will help with nitrogen utilization.
| Cooperator: | Marsh Foundation/ | Fertilizer: | 320 lb/A 9-25-19 broadcast |
| Farm Focus | at planting; variable | ||
| County: | Van Wert | topdress (see Methods) | |
| Nearest Town: | Van Wert | POST (April 17): | 1 pt/A MCPA |
| Soil Type: | Hoytville silty clay loam | Insecticide: | none applied |
| Drainage: | Tile | Variety: | Wellman 9910 |
| Previous Crop: | Soybeans | Row Width: | 7.5 inch |
| Tillage: | No-till | Planting Rate: | 166 lb/A |
| Soil Test (2002): | pH 6.2, P 33 ppm | Planting Date: | October 30, 2001 |
| Rep. 1 and 2 | K 137 ppm | Harvest Date: | July 8, 2002 (Rep. 1 and 2) |
| Soil Test (2002): | pH 6.5, P 85 ppm | July 9, 2002 (Rep. 3) | |
| Rep. 3 | K 249 ppm |
This study was set up with two different nitrogen topdress rates with and without sulfur for a total of four treatments. The treatments are 75 lb/A nitrogen, 75 lb/A nitrogen with 9.4 lb/A sulfur, 100 lb/A nitrogen, and 100 lb/A nitrogen with 12.5 lb/A sulfur. The straight nitrogen treatments were applied using 28-0-0 liquid fertilizer, and the treatments with sulfur were applied using 24-0-0-3 liquid fertilizer. There are three replications of each treatment set up in a complete randomized block design. Two replications are in one field and the third replication is in a second field adjacent to the first field with similar soil type and fertility. The study was planted using a John Deere 750 no-till drill. Plot size is 75 feet wide by 900 feet minimum length.
Harvest populations (July 8) were estimated by counting the number of wheat heads in a one-foot section at 10 different locations in each individual plot. The average of the number of heads counted per one foot was converted to heads per square foot. The center 56 feet of each plot was harvested with a John Deere 6620 combine. Each harvested plot was weighed by a calibrated weigh wagon, and moisture was determined using a Dickey John calibrated moisture meter. Yields reported in this study have been adjusted to 13.5% moisture standard.
Table 1. Harvest Population, Moisture, and Yield.a
| Treatment | Harvest Population | Moisture | Yield |
| (heads/ft2) | (%) | (bu/A) | |
| 100 lb./A nitrogen + 12.5 lb./A sulfur | 64.0 a | 12.7 | 83.2 a |
| 100 lb./A nitrogen | 55.0 b | 12.7 | 79.4 ab |
| 75 lb./A nitrogen + 9.4 lb./A sulfur | 58.0 b | 12.8 | 75.8 bc |
| 75 lb./A nitrogen | 54.3 b | 12.9 | 71.7 c |
| LSD (0.05) | 5.1 | NS | 4.1 |
| F-test | 9.1 | <1 | 17.0 |
| a Means followed by the same letter in the same column are not significantly different. | |||
NS = not significant
Results from this one-year study indicate that the addition of 25 lb/A nitrogen significantly increased yields when independently comparing the two nitrogen rates with sulfur and the two nitrogen rates without sulfur. It has been suggested that sulfur added to the nitrogen application increases the efficiency of nitrogen. Although the addition of sulfur may have possibly helped with nitrogen utilization, the addition of sulfur at equivalent nitrogen rates did not significantly improve yields in this study.
According to the Tri-State Fertilizer Recommendation for Corn, Soybeans, Wheat, and Alfalfa (Extension Bulletin E-2567, Rep. August 1996), no accurate soil test exists for sulfur at this time. The decision to apply sulfur should be based on the following criteria and observations - low organic matter, sandy soils, and visual symptoms such as a yellow color in the presence of adequate nitrogen. A plant analysis is the best diagnostic tool for confirming sulfur availability.
The authors express appreciation to Dan Recker, Ohio City Mercer Landmark, for his cooperation and technical assistance with this study.
For additional information, contact:
Andy Kleinschmidt or Gary Prill
Ohio State University Extension, Van Wert County
1055 South Washington Street
Van Wert, OH 45891
419-238-1214
kleinschmidt.5@osu.edu or prill.1@osu.edu