Brynn Johnson
Graduate Research Associate, The Ohio State University
Introduction
Increased traffic on community sports fields diminishes turfgrass coverage. To address this issue, this project aims to find the optimal combination of mowing height and nitrogen rate for tall fescue and Kentucky bluegrass under traffic. These turfgrasses were selected since Kentucky bluegrass is the most commonly used turfgrass for recreational sports fields in Ohio, while tall fescue is a lower-input alternative.
This experiment will test three mowing heights and six fertilizer rates over two years, 2024 and 2025. By fine-tuning management practices, we aim to equip sports field mangers with the tools to maintain high-quality turfgrass, despite unpredictable and often excessive use.
Optimizing mowing height and nitrogen rate is crucial as these are controllable factors in an environment where traffic levels are often beyond the sports field manager’s control. This research will help allocate resources efficiently by determining the most cost-effective mowing and fertilization strategies for different turfgrass conditions.
Objective
Determine the effect of mowing height and nitrogen fertilizer rate on the simulated athletic field traffic tolerance of (1) tall fescue and (2) Kentucky bluegrass.
Materials and Methods
- Mowing Program
- Mowing occurs with a walk-behind rotary mower and clippings are returned
- 1.5 inch mowing height: mowed on Monday, Wednesday, and Friday
- 2.5 inch mowing height: mowed on Monday and Friday
- 3.5 inch mowing height: mowed on Monday
- Fertilizer Program
- 0, 1, 2, 3, 4, and 5 lb N/1000ft2 are applied every two weeks (June-October) and watered in directly afterwards
- Granular fertilizer was applied in the form of ammonium sulfate (21-0-0)
- Traffic Program
- Traffic will occur August through October for 10 weeks using a modified Baldree traffic simulator (Toro ProCore 648)
- These traffic events will occur 3x/week on Tuesday, Wednesday, and Thursday
- Data Collection
- Data will be collected 1x/week for ten weeks starting in August
- Turfgrass coverage will be assessed weekly using digital image analysis
- Surface hardness will be collected weekly using the Clegg Impact Soil Tester (2.25 kg)
- Rotational resistance will be assessed weekly using a Shear Vane
- Soil moisture and temperature sensors have been installed at three different points throughout each trial area to continuously monitor these parameters
Expected Results
The objective of this project is to find the optimum combination of mowing heights and nitrogen rate under traffic stress. It is expected that higher amounts of nitrogen will increase green cover, though we do anticipate that there will be a point where additional fertilizer will not improve the quality of the turfgrass. We also expect that the optimal nitrogen rate for traffic tolerance may vary depending on mowing height. Additionally, each species may require different nitrogen rate and mowing height combinations for optimal performance. Overall, we aim to find the best nitrogen rate and mowing height combinations so that sports field managers can allocate their resources efficiently in different conditions.