Turfgrass quality is visually evaluated by human assessors based on a scale
of 1(the grass is dead) to 9 (the grass if of outstanding quality) in the current
assessment method. This evaluation practice has several disadvantages and therefore,
there is the need for a better evaluation technique. Individual biases are inevitable
and lead to some level of inconsistency, even among the most highly trained
The Field Scout TCM 500 NDVI Turf Color Meter measures reflected
light from turf grass in the red (660 nm) and near infrared (850 nm -NIR) spectral
bands. Research from Clemson University, Predicting Visual Quality Ratings of
Turfgrass Research Plots Using Spectral Reflectance (Roy B. Dodd, ASAE etal.)
is the basis for the technology used in this meter. NDVI denotes Normalized
Difference Vegetative Index.
Since chlorophyll absorbs the red band (660 nm) of incoming radiation, the
reflectance is relatively low due to the strong absorption of the light by the
plant pigments. The high reflectance in the NIR (850 nm) band is caused by the
cellular structure of the plant leaves particularly the spongy mesophyll leaf
Red & NIR values are presented in three modes: as an index (0 to
99) of Red/NIR in %, NDVI, and Grass Index (ie. 7.3).
Download the manual.