Evaluation of Methods for Quantifying Thatch Accumulation in Zoysiagrass.

In the absence of regular management, zoysiagrass (Zoysia spp.) thatch can be problematic and result in unacceptable turf quality. At least three methods of measuring thatch are used in turfgrass science including: percent organic matter (OM) by weight-loss-on-ignition (WLOI), depth by ruler, and mass by balance. The objective of this study was to determine if the faster Volk “thatchmeter” instrument accurately measured thatch and correlated to the three aforementioned methods. The four methods were evaluated as part of a field study designed to determine the influence of fertility and cultural management practices on thatch development of five zoysiagrass cultivars. Treatments were verticutting, topdressing, and fertilization arranged in a split-split-plot design with four replications. Treatments and thatch measurements were conducted for three years in Jay, FL. The thatchmeter resulted in lower F-values on Z. japonica than on Z. matrella cultivars indicating the instrument had reduced sensitivity on the higher cut Z. japonica cultivars. Linear regression of the thatchmeter and the WLOI, ruler, and mass measurements resulted in 80% of the R² values being less than 0.1. The increase in turf leaf blades likely contributed to the reduced sensitivity of the thatchmeter on Z. japonica cultivars. Although the thatchmeter sensitivity increased on the Z. matrella cultivars, the instrument still failed to accurately measure and correlate to WLOI, ruler, or mass measurements.