ARS | Publication request: Effect of compost-, sand-, or gypsum-amended waste foundry sands on turfgrass yield and nutrient content

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 2009
Publication Date: N/A

Interpretive Summary: Each year the U.S. metalcasting industry generates several million tons of waste foundry sand (WFS), which has a potential to be beneficially used as aggregate in potting soils. Reuse of WFSs can help reduce the amount going to landfills and associated disposal costs, and conserve natural resources. In this study we blended up to 100% WFS with compost or commercial play sand and determined the effect on the growth of perennial ryegrass and tall fescue. In addition, the nutrient content of the grasses was determined at various stages of growth. Based on an evaluation of shoot growth, root growth, and percent surface coverage it was determined that a compost blend containing 40% WFS was optimal as it incorporated the greatest possible amount of WFS without a major reduction in turfgrass growth. While the grass tissues from the 40% WFS blend were determined to be deficient only in calcium, no micronutrient deficiencies were observed, suggesting that WFS can be successfully used as a component in potting soils.

Technical Abstract: To prevent the 7-11 million metric tons of waste foundry sand (WFS) produced annually in the U.S. from entering landfills, current research is focused on the reuse of WFSs as soil amendments. The effects of different WFS-containing amendments on turfgrass growth and nutrient content were tested by planting perennial ryegrass and tall fescue in different blends containing WFS. Blends of WFS were created with either compost or acid-washed sand (AWS) at varying percent by volume with WFS, or by amendment with gypsum (9.6 g gypsum/kg WFS). Measurements of soil strength, shoot and root dry weight, plant surface coverage, and micro-(Al, Fe, Mn, Cu, Zn, B, Na) and macronutrients (N, P, K, S, Ca, Mg) were performed for each blend and compared to pure WFS and to a commercial potting media control. Results showed that strength was not a factor for any of the parameters studied but the K/Na base saturation ratio of WFS:compost mixes was highly correlated with total shoot dry weight for both perennial ryegrass (r = 0.995) and tall fescue (r = 0.94). This was further substantiated as total shoot dry weight was also correlated with shoot K/Na concentration of perennial ryegrass (r = 0.99) and tall fescue (r = 0.95). A compost blend containing 40% WFS was determined to be the optimal amendment for the reuse of WFS as it incorporated the greatest possible amount of WFS without major reduction in turfgrass growth.