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Combining Carbon Sequestration & Phosphate Mining Reclamation in Florida.


The following efforts reflect our continued research approach to reduce greenhouse emission levels through cost effective and common sense actions.

Background: In 2004, three major hurricanes tracked through central Florida creating vast amounts of tree waste (biomass) debris. The primary actions taken to dispose of this debris were: (1) Open Field Burning; (2) Landfilling. Under both of these options, significant amounts of greenhouse gases would be released either immediately (CO2 from burning) or through time (methane creation from landfilling).

Picture of Processed Hurricane Debris (from a Tub Grinder): Entrained dirt is estimated to be ~10% on average. Also, note the wide variance in chip size from a fine mesh to large pieces.

Soil and Weed Science on Environmentally Damaged Lands:   From our research in growing energy crops on abandoned phosphate mine clay settling areas (CSAs), two soil and agriculture based facts are clear:

  • Even after decades after the cessation of mining operations,
        CSA soils are extremely deficient in organic matter and
        available nitrogen needed for "healthy soils" to support good
        tree and flora growth.
  • For the majority of older CSAs in central Florida, these
        abandoned mined sites have been invaded and are now
        dominated by cogongrass (considered by the USDA one of
        the most destructive weeds in the World).
  • Prior to energy crop plantings (e.g., crops such as sugarcane, sorghum, corn, soybeans, trees, etc.), our site was typical of most older CSA sites -- a prairie of cogongrass ~5 to 6 feet in height.

    Mulch Matting Research: As an alternative to open field burning or landfilling, the Federal Emergency Management Authority and sub-contractors of FEMA accepted our plan to use hurricane wood waste debris at our energy crop farm. Under this plan, chipped wood waste debris was accepted at our site with no tipping/disposal fee to FEMA. However, FEMA's subcontractors were required to spread the wood waste mulch at no cost to us.

    Each truck contained approximately 22 tons of mulch per load.

    When mulch was spread with a trac front end loader over the CSA, a base/pad was thus created to support the heavy weight of trucks.

    Approximately 60,000 tons of hurricane wood waste debris have been spread over test plots at average mulching depths of 3 feet.

    The objectives of this "mulch matting" research effort are threefold:

  • To see if heavy mulching will smother out cogongrass.
  • To build soil organics in the carbon deficient mined lands.
  • To improve soil hydrology/drainage.

    In test plots, the tree chip mulch was spread over
    cogongrass that was approximately 5 feet in height.

    Future Focus of Mulch Research Efforts: According to University of Florida Scientists, in approximately 9 to 12 months the mulch will have decomposed enough to support crop planting (e.g., row crops, trees). During this period we will be planting legumes (treated with nitragin innoculants) into the mulched areas to:

  • Increase available nitrogen in the developing soil.
  • Establish ground cover that hopefully will stabilize test plot
        areas from cogongrass reinfestation (via wind born seed).
  • Potential legumes to be planted include: Mimosa Strigillosa, Aeschynomene, Alyce, Mt. Barker, Red Clover, Alfalfa, Soybeans, Partridge Pea, Lupines, Birdsfoot Trefoil, Perennial Peanut, Vetch, and Sainfoin.

    Carbon Sequestration: In the coming year we will be working with Scientists at the University of Florida, the Department of Energy's Oak Ridge National Lab (ORNL), and others to document the net benefit in CO2 emissions through the following conceptual methodology:

  • First we will calculate the CO2 emissions that would have
        occured if the hurricane biomass wastes had been open
        field burned.
  • Next we will estimate the CO2 released from the mulch as
        it decomposes.
  • The net between the two above methods will be reported as
        carbon sequestration under the U.S. Department of Energy's
        Voluntary Greenhouse Gas Reporting Program.