Stable and Labile Nitrogen and Carbon Pools in Coal Mine Soils Reclaimed with Poultry Manure.

Soil labile nitrogen pools are susceptible to mineralization and subsequent leaching losses that can negatively impact water quality.  Poultry manure, produced in excess of crop needs in Pennsylvania, could be applied to abandoned coal mine soils, but large application rates required for successful revegetation could result in significant nitrogen discharge.  Therefore manure amendment practices should be designed to produce large stable pools of nitrogen and carbon to retain added nutrients and restore long-term nutrient cycling.  A one-year lab incubation experiment was conducted to maximize nitrogen mineralization and determine stable and labile nitrogen and carbon pools in mine soils.  Amendment treatments used were lime plus fertilizer, two rates of composted poultry manure and two blends of fresh poultry layer manure mixed with paper mill sludge (C:N ratios of 20:1 and 30:1).  Soils were incubated immediately following amendment application (year one) and one year after field application (year two).  In the year one experiment, nitrogen leaching did not differ among treatments, indicating all treatments have equal potential of nitrogen leaching loss.  The 20:1 C:N manure and paper mill sludge treatment was as effective as the lower rate of compost in retaining N (80% of added nitrogen).  In both incubations, organic treatments were more effective at building large stable nitrogen and carbon pools than lime plus fertilizer.  In the year two experiment, organic amendment stable nitrogen pools were larger than the year one experiment, suggesting even more nitrogen and carbon is sequestered in the field than indicated by the year one incubation results.  Manure and paper mill sludge had more microbial biomass after two years, which could translate to enhanced, long-term nutrient cycling.  These results show that both composting poultry manure and mixing paper mill sludge with manure can effectively minimize manure leaching losses and enhance nutrient sequestration compared to lime and fertilizer.