Ecology is the study of living organisms and how they relate to each other and their physical environment. The resources required for life are always limited, and the species that thrive in a given environment are the ones who best utilize the available resources. In turf ecosystems, we manage factors to maintain consistent, uniform conditions. Examples include the following:
In all of these scenarios, there is a balance at play. All of the environmental factors are present at the same time, working together to create the growing environment for the turf. For the most part, we manage all of these factors successfully to create an ideal environment to grow grass.
But sometimes, despite our best efforts, nature reminds us that we aren’t in control. In these situations, we see ecology unfold and create unique management challenges in turf systems.
Turf is relatively resilient to water stress. Some species can enter dormancy when water supplies are limited (e.g., Kentucky bluegrass). Other species can avoid drought by producing deeper root systems that maximize access to limited water resources (e.g., tall fescue). But even the most resilient turf can eventually die under extreme water stress.
Figure 1: The plot treated with wetting agent (left) shows no localized dry spot. The untreated plot (right) shows localized dry spot caused by hydrophobic soil.
In Figure 1, the creeping bentgrass plot on the left was treated with a wetting agent, which prevented localized dry spot (LDS) from developing. The plot on the right was not treated with a wetting agent, and when the soils became dry, soil hydrophobicity resulted in LDS and, eventually, the loss of turf. In both photos, hydrophobic conditions and dry turf are also visible in the alleys between treated plots.
Figure 2: The wetting agent study from Figure 1, one year later. The turf loss reduced the density in the alleys between plots, and the effects were still visible the following season.The wetting agent study from Figure 1, one year later. The turf loss reduced the density in the alleys between plots, and the effects were still visible the following season.
The photo in Figure 2 was taken from the same study area, one year later. The hydrophobic conditions in the alleys between plots eventually led to the loss of turf in those areas, and the impacts are still visible!
In the first year of the study, prior to the onset of water stress, organic hydrophobic coatings were likely present in the soil. When irrigation was reduced, the hydrophobic untreated plots and alleys became drier than the treated areas. When the soil moisture dried below the wilting point of the turf, water stress appeared in these hydrophobic areas. Once the water stress appeared and became widespread, the irrigation was then increased to try to bring back the wilted turf.
Despite bringing back the irrigation, some of that wilted turf did not recover. At this point, we created an environment with adequate moisture and excellent access to sunlight, but no turf left to compete and take advantage of those resources. Nature is full of opportunity, and in this scenario, moss and algae were there the whole time, waiting for the perfect moment. When moisture returned and was no longer a limiting resource, these species took advantage and began thriving in spots with limited turf canopy.
Over the following weeks and months, the turf was unable to spread and grow effectively into these areas where other species took hold and outcompeted the grass. A problem that started out as water stress eventually became a challenge in managing species competition, all based on the ecology of the system as different species compete for those limited resources.
Managing turf or crops means managing ecological systems. While we are often focused on solving one problem at a given time (e.g., spraying for broadleaf weeds), it is important to step back and appreciate the broader ecological factors in the systems we manage. Using a quality wetting agent can help prevent turf loss, but a product application will be most effective when combined with careful irrigation management. Proper management of site conditions can prevent high weed pressure while using a quality adjuvant can significantly improve weed control.
A holistic view of all the environmental and cultural factors that contribute to pest problems are part of Integrated Pest Management (IPM). Balancing these factors, along with establishing a threshold for how much damage we can tolerate, give us the best chance to manage our systems effectively and efficiently.
Wielding his 35 years of experience, Mark Mahady provides insight on irrigation and water conservation, turf and soil moisture management, wetting agents, surfactants, and other related topics in this edition of Cutting-Edge Perspectives.
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