Using a Chlorophyll Meter to Determine the Chlorophyll Concentration, Nitrogen Concentration, and Visual Quality of St. Augustinegrass

<jats:p>Because high rates of nitrogen fertility are necessary for producing high-quality turfgrasses, quick, reliable methods of determining the N status of turfgrasses would be valuable management tools. The objective of this study was to evaluate the capacity of a hand-held chlorophyll meter (SPAD-502) to provide a relative index of chlorophyll concentrations, N concentrations, and visual quality in St. Augustinegrass [<jats:italic>Stenotaphrum secondatum</jats:italic> (Walt.) Kuntze]. Two experiments were conducted in a greenhouse in 1998 to evaluate the utility of SPAD readings. Established pots of `Floratam' were subjected to weekly foliar Fe treatments at Fe rates of 0 and 0.17 kg·ha<jats:sup>–1</jats:sup> for 4 weeks. Six weekly nitrogen fertilizer treatments were applied in the form of ammonium sulfate at N rates of 0, 5.75, 11.5, 17.25, and 23 kg·ha<jats:sup>–1</jats:sup> for 4 weeks. Greenhouse SPAD readings were not affected by Fe treatment, but N treatments resulted in differences in SPAD readings, visual quality, and chlorophyll concentrations. The readings were positively correlated with chlorophyll concentrations (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.79), visual ratings (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.74), and total Kjeldahl nitrogen (TKN) (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> = 0.71). Readings taken from field-grown `Floratam', `Floratine', and `Floralawn' St. Augustinegrass were poorly correlated (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> < 0.63) with chlorophyll concentrations and TKN. Unless future techniques improve dependability of the SPAD meter under field conditions for measuring chlorophyll and N concentration of a stand of turfgrass, the usefulness of such readings for the management of St. Augustinegrass seems limited.</jats:p>