Mark Freeman
Here are some ingredients that make for a healthy lawn—grow an attractive turf without excessive usage of water, fertilizer and pesticides. This goal is dependent on your soil depth and quality, watering practices, rooting depth of turf, weather, and overall management practices. So, let’s focus on what you can do after the turf and irrigation system is installed.
Most of us have clayey soil that is high in pH. Our main task with irrigation is when to water and how much to use. Most of us are using the fixed spray pop up heads with multiple stations around the yard. For new yards, the builder has set the controller to irrigate several days a week for new turf. You need to decrease the days once turf is established.
Irrigation management is composed of application uniformity and efficiency. Uniformity measures how evenly that water is distributed across the field. Ideally, you want head-to-head coverage (each spray reaches each head). You can get dry spots with broken or miss-matched sprinkler heads. Efficiency is measured by the percent of applied water that roots don’t receive, such as runoff or evaporation due to high temperatures or wind. You can increase the efficiency by not watering between the hours of 10 a.m. to 6 p.m., as this increases evaporation and wind drift. Watering early in the morning allows the turfgrass leaves to dry and lowers the chance of fungal diseases.
Rooting depth is one of the most important factors for success. The goal is to establish a deep root zone of six to eight inches deep and then push water throughout it. Clayey soil has a high water storage capacity (per inch of soil) but it has a slower initial infiltration rate than loam or sand. Think of clay as your “gas storage tank”, where it holds more water if you allow the roots to grow deeper and match the slower infiltration rate, so water remains in the root zone. Clay soils have an infiltration rate of 25% or lower compared to sand. Most of our fixed rate sprinklers exceed that and you can easily see water runoff after five to eight minutes. To remedy this issue, run all your stations for several minutes (before runoff occurs), then repeat. This is called “cycle and soak” watering. This action allows more infiltration and less runoff into the streets but using the same amount of water.
Action to take now. With the cooler weather, y’all can cut back to irrigating twice a week, and irrigate between 6 p.m. to 10 a.m.
With mowing, don’t remove more than one third of the plant at a time. Consider mulching the clippings (versus bagging) as it represents about 50% of the nitrogen needed for turfgrass.
You can add fertilizer, mostly all-nitrogen at this time, through mid-October.
After the hot summer and stress, note locations of the weaker lawn areas and try to figure out the cause(s). Consider using the cycle and soak routine if you have lots of runoff.