Environmental Pollution 88 (1995) 161-165 Elswier Science Limited Printed in Great Britain. ROLE OF EXPANDED CLAY AND POROUS CERAMIC AMENDMENTS ON PLANT ESTABLISHMENT IN MINESPOILS D. A. H. Figge, B. A. D. Hetrick* & G. W. T. Wilson Department of Plant Pathology, Kansas State University, Manhattan, Kansas 66506, USA Abstract Greenhouse experiments were conducted to examine the impact of expanded clay (Turface) or porous ceramic (Isolite) amendments on germination, biomass production, plant Zn concentration, and Zn accumulation by Festuca arundinacea grown in mine tailings. Because previous studies have demonstrated that fertilization is essential for plant growth in these tailings, manure was also added to the tailings. Plant growth and germination were greatest tf the expanded clay was added topically to the tailings. To a lesser extent, plant growth and germination was also stim- ulated by topical additions of porous ceramic. However, no benefit was observed tf either amendment was mixed into the top 10 cm of the mine tailings. The concentration of Zn in F. arundinacea tissues was lowest tf the ex- panded clay was added topically to the mine tailings. Roots growing in the layer of clay or ceramic amendment appeared to be smaller, finer, and more abundant than the large, coarse roots found throughout the tailings-manure mixture. These results suggest that topical application of an expanded clay or porous ceramic product will increase seed germination and improve plant establishment and growth in contaminated minespoils. INTRODUCTION Zinc and lead mining in southeastern Kansas, north- eastern Oklahoma, and southwestern Missouri began in the late 1800s and continued through the 1950s. The abandoned mining areas now consist of acres of mine tailings (chat) often left on the soil surface in large piles. These tailings contain 13 700, 1 150, and 89 pg g-’ total Zn, Pb and Cd, respectively (Abdel-Saheb et al., 1994). Levels in excess of 10-300, 100 and 3 pugg-’of Zn, Pb, and Cd, respectively, are considered phytotoxic and therefore environmentally hazardous (Munshower, 1994). Wind and water erosion, infiltration and percolation of water through mine wastes increases the potential for human ingestion in neighboring communities (Norland, 1991) which led the US Environmental Protection Agency in 1983 to add 285 km2 of Cherokee County, Contribution No. 94-273-J, from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas, USA. * To whom correspondence should be addressed. 161 Kansas to the National Priorities List. Because of its significant hazards, in 1985 this area was declared a Su- perfund (Plan0 & Greenburg, 1989) site by the EPA, with remedial efforts to revegetate the area given high priority (Norland, 1991). Although revegetation of tailings would reduce wind and water erosion from the minespoil, previous experi- ments have determined that tailings have limited micro- bial activity and are a poor medium for growing plants (Shetty et al., 1994a). Poor water- and nutrient-holding capacity and high levels of Zn in the tailings appear to impede plant establishment. Studies on the role of mi- croorganisms in revegetation of contaminated soils have shown that inoculation with vesicular-arbuscular mycorrhizal fungi alone significantly increased the biomass of plants grown in soil containing high levels of Zn but had no effect on the biomass of plants grown in tailings (Shetty et al., 19946). Norland (1991) in- creased plant establishment in tailings by using organic amendments of composted yard waste, spent mush- room compost, and cattle manure. These amendments have high cation exchange capacity, can form stable or- ganic-heavy metal complexes in contaminated soil, and act as a slow-release fertilizer (Norland, 1991). A study by Hetrick et al. (1994) reported that growth of Andro- pogon gerardii and Festuca arundinacea in tailings was achieved if N and P fertilization was coupled with myc- orrhizal fungus inoculation, whereas those plants with- out mycorrhizae failed to grow even if fertilized. In the absence of mycorrhizae, plants grew in tailings only if the expanded clay product, used to improve the water- and nutrient-holding capacity of the tailings, and N were added together (Hetrick et al., 1994). Thus, this or other clay products coupled with fertilization may sub- stitute for the more costly and less feasible microbial amendment. The first experiment in this study examined the im- pact of an expanded clay and a porous ceramic, both used to improve water-holding capacity of soils, and their rate of application on biomass production in tail- ings amended with organic matter (steer manure). The addition of phosphorus was also assessed in this experi- ment to determine its effect on plant growth in tailings. This experiment and the former experiments were con- ducted with seedlings that were germinated in vermi- culite and later transplanted. A large-scale revegetation project, however, would only be cost effective if the