Productivity of clay tailings from phosphate mining: I. Biomass crops

Journal Article · · Journal of Environmental Quality; (USA)

DOI:https://doi.org/10.2134/jeq1989.00472425001800010017x· OSTI ID:6995982

Mislevy, P ^[1]; Blue, W G; Roessler, C E ^[2]

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1. Univ. of Florida, Ona (USA)
2. Univ. of Florida, Gainesville (USA)

Phosphate mining in Florida has waste products of phosphatic clay and quartz sand tailings, each making up about one-third of the original matrix (PO{sub 4} ore, sand, and clay). Phosphatic clay ponds typically occupy about 50% of the mined sites and normally require 10 to 15 yr before 40 to 50% solids are obtained. These clays contain no phytotoxic materials and are high in most plant nutrients. When surface water has disappeared, these clays are classified as clayey Haplaquents. A split-plot field experiment was conducted to study biomass yield, quality, plant nutrient concentrations, changes in soil nutrients, and {sup 226}Ra. Seven biomass crops -(i) elephantgrass (Pennisetum purpureum L. PI 300086), (ii) leucaena (Leucaena leucocephala (Lam.) De Wet), (iii) alemangrass (Echinochloa polystachya (H.B.K) Hitch), (iv) erianthus (Erianthus arundinaceum (Retz) Jews IK 76-63'), (v) desmodium (Desmodium cinerascens A. Gray), (vi) sweet sorghum (Sorghum bicolor (L.) Moench USDA M 81E), and (vii) forage sorghum (Sorghum bicolor (L.) Moench Pioneer 931) - were grown on the phosphatic clay with and without a 5-cm surface layer of quartz sand tailings. Nitrogen was the only fertilizer element applied for grass species and no fertilizer was applied for legumes during the 4-yr period. Dry biomass yield averaged over 4 yr for erianthus, leucaena, and elephantgrass averaged 139.6, 58.5, and 56.5 Mg ha{sup {minus}1} yr{sup {minus}1}, respectively. Crude protein and digestibility were low in mature, whole-plant samples except for leucaena (122.0 g kg{sup {minus}1}). Generally, all whole plants contained adequate concentrations of nutrients. Mehlich-I-extractable soil nutrient concentrations changed little over the 4-yr period. Radium-226 concentration in plant tissue (0.23 pCi g{sup {minus}1}) was nearly six times higher than the concentration measured in plants from an unmined surface Spodosol (0.04 pCi g{sup {minus}1}).

• OSTI ID: 6995982
• Journal Information: Journal of Environmental Quality; (USA), Vol. 18:1; ISSN 0047-2425
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
PLANTS
RADIOECOLOGICAL CONCENTRATION
TAILINGS
PRODUCTIVITY
BIOMASS
CLAYS
FLORIDA
MINING
NUTRIENTS
PHOSPHATES
RADIUM 226
SOILS
USES
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
CARBON 14 DECAY RADIOISOTOPES
ECOLOGICAL CONCENTRATION
ENERGY SOURCES
EVEN-EVEN NUCLEI
FEDERAL REGION IV
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
ISOTOPES
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
RADIOISOTOPES
RADIUM ISOTOPES
RENEWABLE ENERGY SOURCES
SOLID WASTES
USA
WASTES
YEARS LIVING RADIOISOTOPES
540230* - Environment
Terrestrial- Radioactive Materials Monitoring & Transport- (1990-)