Nutrient Leaching and Switchgrass Growth in Mine Soil Columns Amended With Poultry Manure

In Pennsylvania, land disturbance from 150 years of extensive coal mining and intensive animal production that produces manure nutrients in excess of crop needs have degraded ecosystems and water quality. Excess manure could be used in mine reclamation, but the large application rates required for successful revegetation could result in significant nutrient discharge. This greenhouse experiment investigated two approaches to minimizing the potential for nutrient leaching of poultry layer manure used for mine reclamation: composting and C:N ratio adjustment. Columns of mine soil were amended with manure only, manure mixed with short-fiber paper mill sludge (C:N ratios of 20-40) and three rates of composted manure. Mine soil was planted with switchgrass (Panicum virgatum L.) to test biomass production of this potential biofuel, and columns were periodically leached and biomass was harvested during the 8-month experiment. Amendment with manure only resulted in the largest leaching of NO3--N (192 mg column(-1)) and P (12 mg column(-1)), whereas nutrient leaching from compost-amended soil was less than or equal to 1.67 mg NO3--N and 3.38 mg P column(-1). Each level of compost addition increased switchgrass growth compared with unamended soil, and mine soil amended with manure and paper mill sludge further increased switchgrass growth while decreasing cumulative NO3- and P leaching compared with manure alone. Although composting manure was most effective at limiting nutrient leaching, our results demonstrate that coapplication of manure with a high carbon material could provide superior biomass production on mine soil while also controlling nutrient loss via leaching.