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FROM THE LAWN INSTITUTE FROM THE LAWN INSTITUTE


THATCH, FRIEND OR FOE?


establish. As a result, new plants rooted in this environment are more prone to injury from traffic, cold, drought, or other stresses. It also can create a habitable environment for insect pests such as chinch bugs, sod webworms, cutworms, and armyworms. In fine turf systems such as sand-based athletic fields or golf course putting greens, thatch also can contribute to a hydrophobic environment that leads to localized dry spots and increased disease pressure from colonies of fungi that live in soil and thatch.


Turfgrass leaves, stems, and roots co-exist in various layers of lawns and other turfgrass systems. While they are all part of the same plant, they each contribute differently to what ultimately becomes what we know as soil organic matter. Tis is due in part because each contains various amounts of lignin, a compound in plants that adds hardness and rigidity to the walls of plant cells. Stems, such as rhizomes and stolons, contain higher amounts of lignin and therefore decompose more slowly than turfgrass leaves, which contain lower amounts. While soil organic matter is an important component of soil health, thatch provides its own unique set of challenges that must be managed properly to maximize its benefits.


Tatch is the layer of undecomposed or partially decomposed organic residues sitting above the soil surface. In turfgrass systems, it most often consists of dead or decaying turfgrass leaves and stems. Tatch accumulates when the production of plant biomass exceeds the rate of its decomposition. Tis can be due to management practices, weather, soil microbial activity, and more. Tatch is not necessarily a bad thing and often is beneficial. It can produce softer, safer athletic fields; it contributes positively to soil organic matter as it decays; it can bind pollutants from urban runoff as it moves through turfgrass systems; it protects the crowns of turfgrass plants from temperature extremes; and it can act as a type of mulch that prevents the soil surface from drying.


However, when thatch accumulates excessively, it can create an imbalance that should be addressed. Tis is because thatch also has poor nutrient and water-retention characteristics that make it difficult for new roots to


For more information on lawn care and helpful “How to” tips, visit The Lawn Institute at: www.TheLawnInstitute.org.


TPI Turf News November/December 2018 9


Terefore, turfgrass managers often battle thatch, especially in intensively managed settings. It can be managed preventively, curatively, or both. Nitrogen is the nutrient most associated with thatch management because over-applying this nutrient can lead to the growth and accumulation of leaf tissue faster than soil microbes can decay them. Preventive thatch management includes a properly balanced nitrogen management plan that avoids excessive growth and also may include leaf clipping collection. Curative methods for thatch management include physical removal of excessive thatch. Tis can be done through aerification, verticutting and/or scalping followed by core and/or clipping removal. When coupled with sand topdressing, each of these practices are very effective at restoring the balance of organic matter with mineral soils.


Te goal should not be to remove all thatch, but instead to manage it at a level that preserves a delicate balance between organic matter and mineral soils, with a gradual transition moving downward through the soil profile. Regardless of how thatch is managed, this important component of turfgrass systems is an asset and should be accounted for in any successful turfgrass management program.


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