Nutrient leaching and soil retention in mined landreclaimed with stabilized manure

Two environmental problems in Pennsylvania are degradedmined lands and excess manure nutrients from intensive animalproduction. Manure could be used in mine reclamation, but thelarge application rates required for sustained biomass productioncould result in significant nutrient discharge. An abandoned minesite in SchuylkillCounty, Pennsylvania, was used to test manurenutrient stabilization by composting and by mixing with primarypaper mill sludge (PMS). Reclamation treatments were limeandfertilizer, composted poultry manure (78 and 156 Mg ha^-1), andpoultry manure (50 Mg ha^-1) mixed with PMS (103 and 184Mg ha^-1) to achieve C-to-N ratios of 20 and 29. Leachates werecollected with zero-tension lysimeters, and during 3 yr followingamendment application, <1% of added N leached fromthe composttreatments. The manure+PMS C:N 29 treatment leached more Nthan any other treatment (393 kg N ha^-1 during 3 yr, 12.4 times more N than compost treatments), mostly as pulses of NO₃^- in the first two fall seasons following reclamation. The manure+PMS C:N 20 treatment leached 107 kg N ha^-1 during 3 yr. Three yearsafter amendment application, most of the N and P added withthe manure-based amendments was retained in the mine soil eventhough net immobilization of N by PMS appeared to be limitedto 3 mo following application. Composting or mixing PMS withmanure to achieve a C-to-N ratio of 20 can effectively minimizeN leaching, retain added N in mine soil, and provide greaterimprovement in soil quality than lime and fertilizer amendment.