Switchgrass Production and Nutrient Sequestration in Abandoned Mine Soils Reclaimed with Poultry Manure.

In Pennsylvania, 150 years of extensive coal mining has left an estimated 250,000 acres of severely degraded mined land and impaired streams.   In the same region, concentrated animal production facilities produce manure in excess of crop needs, creating an increased risk of nutrient pollution in surface and groundwater.  Excess poultry manure could be used in mine reclamation, but the large application rates required for successful revegetation could result in significant nutrient discharge.  Furthermore, abandoned mine lands could be used to grow switchgrass (Panicum virgatum L.), a biofuel crop, to return these lands to productivity.  To achieve high production rates, however, significant and sustained nutrient levels are necessary.  A field experiment in Schuylkill County, Pennsylvania, was established in April 2006 to measure the effects of poultry manure and carbon on vegetation and soil nutrients.  Treatments included a lime and fertilizer control, two rates of composted poultry manure (78 and 156 Mg ha^-1 dry weight), and two blends of fresh poultry layer manure (50 Mg ha^-1 dry weight) mixed with paper mill sludge (103 and 184 Mg ha^-1) to achieve C:N ratios of 20:1 and 30:1.  Two years following switchgrass establishment, yields were 2.5 to 3.6 times greater for organic amendments compared to inorganic lime and fertilizer (111 g m^-2).  Fresh manure and paper mill sludge yields had slightly larger yields than compost treatments.  Soil N sequestration was greater in with compost treatments (2880 and 4780 kg N ha^-1) compared to other treatments; manure and paper mill sludge soil N increased from 820 kg ha^-1 to approximately 2000 kg ha^-1.  Mehlich-3 extractable soil P concentrations were greater in organically amended soils compared to lime and fertilizer.  These results suggest that poultry manure, when applied with a carbon source, can provide superior vegetative growth and nutrient sequestration for biofuel switchgrass production.