No More Paper Bags? Turfgrass Clipping Yield Correlates Well with Normalized Differential Vegetative Index.

Clipping yield provides a useful assessment of turfgrass growth and vigor, but is an operationally cumbersome and labor-intensive procedure. Multispectral reflectance indices, such as the normalized differential vegetative index (NDVI), have been proven to be rapid, indirect measures of turfgrass canopy densities. Field studies were conducted in 2006 and 2007 to investigate correlation of clipping yield and NDVI for ‘Penn A-4’ and ‘Penn G-2’ creeping bentgrass (Agrostis stolonifera L.) plots, managed as golf course putting greens. Plots were maintained at a 3.2-mm mowing height (clippings not returned) and fertilized with N from 14.6 to 43.9 kg ha­^-1 mo^-1. Clipping yield dry mass (kg ha^-1 d^-1) was collected regularly over the course of the studies. Duplicate measures of NDVI (660- and 850-nm) were recorded using a turf chlorophyll meter (TCM 500, Spectrum Technologies, Inc., Plainfield, IL), 3-4 d before clippings were harvested. Significant correlation of clipping yield dry mass and NDVI was detected among the 462 pairs of collected data. Several regression models, with varying predictive potential, were developed to estimate clipping yields of creeping bentgrass putting greens from NDVI. Results indicate indirect estimation of turfgrass clipping yield by NDVI may serve as a potential alternative to direct measurement.