Field-Based Investigations on Stabilization of a Contaminated Military Site Via Combined Use of Soil Amendments and Biofuel Crop Growth.

Keywords: bioenergy, phytostabilization, biofuels, heavy metals, miscanthus

Extensive areas of productive land can be contaminated by critical pollutants due to military activities. The most common and widespread contaminant in military lands is lead (Pb). A field experiment was established in 2016 at Ft. Riley military reservation, KS, in an area with soil total Pb concentration of about 1000 mg/kg and near neutral soil pH. The main objectives of this study were to determine feasibility of using miscanthus (a second generation biofuel crop) for phytostabilization of this contaminated military site; the effect of soil amendments on miscanthus growth; and the effect of soil amendments on soil-plant transfer, and bioaccessibility of soil Pb. The field experiment was established as a randomized complete block design with four replications. Based on soil characteristics, five treatments were selected:  (i) control plots without tillage and left with natural vegetation, (ii) no-tillage, no additional amendments and planted with miscanthus, (iii) tilled soil, no additional amendments and planted with miscanthus, (iv) tilled soil amended with  inorganic P (triple superphosphate  applied at 5:3 Pb:P molar ratio) and planted with miscanthus, and (v) tilled soil amended with organic P source (class B biosolids applied as wet weight basis at 45 Mg/ha) and planted with miscanthus. Soil samples were collected before planting and after each harvesting. The above-ground biomass was harvested after about 7 months, and dry matter yield was determined. Subsamples of plant materials were analyzed for nutrients and Pb. Results from the first year showed that tilling and soil amendments increased the dry matter yield. Effects of soil amendments on plant Pb concentration and bioaccessibility will be discussed