What is thatch?

Thatch is that tightly intermingled layer of dead and living parts (roots, shoots, stems, stolon’s, leaf tissue, etc) that develops between the green vegetation and soil surface” Dr Martin Ferguson Leaf clippings contribute very little to thatch build up. Roots, rhizomes and stolons are major contributors to thatch as they have a high lignin concentration and resist decomposition. How much is too much? A thatch layer of up to ½”/13mm can be beneficial as it can improve wear tolerance and insulates the soil from extremes in air temperature. When thatch levels accumulate beyond this the disadvantages far outweigh the advantages. Some of the many problems that can occur are detailed on the following pages. These problems will be exaggerated when excessive thatch layers are present. This worst-case scenario means there is no root structure left and the vicious thatch cycle continues. Thatch production is inevitable and is without doubt one of the most common problems encountered on golf courses and sports surfaces throughout the world. There are many different factors which contribute to excessive thatch accumulation. Some of these factors include grass species, climate, acidic conditions, poor aeration, high nitrogen nutritional levels and over wetting.