Copper Reduces Shoot Growth and Root Development of Creeping Bentgrass

Abstract

Sand‐based golf course putting greens have been observed to contain elevated Cu concentrations, based on standard soil tests. Little research has been conducted that relates Cu concentration in sand media to turfgrass performance. The objectives of this study were to determine the response of greenhouse‐grown creeping bentgrass (Agrostis palustris Huds. ‘Penncross’) to treatments in rooting media that ranged from 0 to 600 mg Cu kg−1 and to provide an estimate of potentially toxic plant‐available Cu levels by use of the diethylenetriaminepentaacetic acid–triethanolamine (DTPA–TEA) soil test. Calcareous and silica sands were mixed individually with reed sedge peat in a 9:1 (v/v) ratio. Penncross sod plugs were placed on the top of pots containing the premixed sand–peat media and allowed to grow for 12 wk. The silica sand medium pH decreased from 6.8 to 5.4, while the pH of the calcareous medium remained between 7.2 to 7.3 as cupric sulfate (CuSO4 · 5H2O) concentrations increased. The average dry weight of clippings for plants grown in silica sand decreased 16% as Cu treatments increased from 0 to 600 mg kg−1 At 600 mg kg−1 Cu, dry root mass was 56 and 48% lower than the control treatments for plants grown in silica and calcareous sand, respectively. The DTPA–TEA soil test extracted, on average, 19% more Cu from the calcareous sand when compared to the silica sand. However, plant roots contained an average of 34% more Cu when grown in silica sand. These results indicate that the DTPA–TEA soil test was not a good predictor of potentially toxic plant‐available Cu in sand‐based media, and alternative soil test methods should be investigated.