Nitrous Oxide Emissions from a Coal Mine Land Reclaimed with Stabilized Manure

Mine‐soil treatment using stabilized manure rapidly sequesters large quantities of organic carbon and nutrients. However, the nutrient‐rich soil conditions may become highly conducive for production and emission of N 2 O. We examined this possibility in a Pennsylvania coal mine restored using poultry manure stabilized in two forms: composted (Comp) or mixed with paper mill sludge (Man + PMS) at C/N ratios of 14, 21, and 28 and compared those with the emissions from conventionally treated soil. The mine soil was extremely well drained with 59% coarse fragments. Soil–atmosphere exchange of N 2 O and CO 2 was determined using a sampling campaign of ten measurements between 16 June and 14 September 2009 (90 days) and 13 measurements between 28 June and 9 November 2010 (134 days) using static vented chambers at ambient and increased moisture (water added) content. Potential denitrification was determined in a laboratory incubation experiment. While non‐amended mine soil did not have a measurable potential for denitrifying activity, the manure‐based amendments introduced the potential. Soil water filled pore space was less than 60% on most sampling days in both ambient and water‐added plots. Daily N 2 O‐N emissions ranged between 40 and 70 g N ha −1 with cumulative emissions of 2–4 kg N ha −1 from non‐amended, lime and fertilizer (L + F) and Comp, and 3–10 kg N ha −1 from Man + PMS treatments. The maximum emission obtained from Man + PMS represented <1% loss of applied N. Although stabilized manure‐treated soil exhibits the potential for N 2 O production, the emission is limited when soils are excessively well drained and reducing conditions rarely develop.