Laccase mediated changes in physical and chemical composition properties of thatch layer in creeping bentgrass (Agrostis stolonifera L.)

Thatch is a tightly intermingled layer of dead and living organic matter present below the turf aerial shoots and above the soil. Excess thatch can be a major problem on many turfgrass sites, especially golf greens. A greenhouse experiment was conducted on dead potted bentgrass (Agrostis stolonifera L.) to eliminate the confounding effects of continual growth as we attempted to determine the efficacy of a ligninolytic enzyme, laccase, along with mediator guaiacol in reducing organic matter content in thatch layer biomass. Laccase was added bi-weekly at 0, 2.06, and 20.6 units of activity cm(-2) with and without guaiacol (2-methoxyphenol) and sampling was performed after two and six months. Parameters investigated included thickness of thatch layer, organic matter, saturated hydraulic conductivity, lignin content, and structural sugars. After two months of treatment application, thatch layer thickness was reduced by 22.1% and extractive-free acid-soluble lignin by 12.3%. Lignin content decreased by 6.5% and saturated hydraulic conductivity improved to 124.7% higher than the non-treated control. No reduction in organic matter and sugar content was observed after two months of treatment application. After six months, thatch layer thickness was reduced by 62.0%, total organic content (0-2.5 cm) by 24.7%, and total sugar content by 29.3%. Extractive-free acid-insoluble lignin and saturated hydraulic conductivity increased by 17.1 and 70.8%, respectively in comparison to the control. These positive responses suggest laccase treatments could expedite organic matter degradation in the thatch layer of creeping bentgrass. (C) 2013 Elsevier Ltd. All rights reserved.