Biosolids and Distillery Effluent Amendment to Irish Miscanthus ×giganteus Plantations: Impacts on Groundwater and Soil

• Published in: Journal of environmental quality 2012-01, Vol.41 (1), p.114-123
• Main Authors: Galbally, P., Fagan, C., Ryan, D., Finnan, J., Grant, J., McDonnell, K.
• Format: Article
• Language: English
• Subjects: Agricultural pollution; Biodegradation, Environmental; Biosolids; Crops; Crops, Agricultural; Energy crops; Environmental regulations; Environmental risk; Food Industry; Groundwater; Groundwater flow; Heavy metals; Industrial Waste; Ireland; Load distribution; Metals; Metals, Heavy; Nitrates; Plantations; Poaceae - metabolism; Sludge; Soil - chemistry; Soil erosion; Soil profiles; Soils; Time Factors; Waste Disposal, Fluid - methods; Water pollution; Water Supply - analysis
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2011.0138

It is necessary to determine the risk of water pollution arising from amendment of organic by‐products (OBs) to energy crops under Irish conditions. Therefore, the impact of landspreading two OBs on the quality of groundwater underlying plantations of Miscanthus X giganteus was assessed. Municipal biosolids and distillery effluent (DE) were spread annually (for 4 yr) on six 0.117‐ha treatment plots at rates of 100, 50, and 0%. The 100% rate represented a maximum P load of 15 t ha−1 as per Irish EPA regulation. Groundwater was sampled for 25 mo and tested for pH, electrical conductivity, NO3−, orthophosphate (PO43−), total soluble P, K+, Cu, Cd, Cr, Pb, Ni, and Zn. Assessment of quality was based on comparison with Irish groundwater threshold values (GTVs). The study was limited to within‐plot using a “well bottom” approach and did not investigate movement of groundwater plumes or vectors of percolation through the soil profile. Mean groundwater concentrations did not exceed GTVs during the sampling period for any species, with the exception of groundwater PO43− in the 100% DE plot, which was almost double the GTV of 0.035 mg L−1. There was no significant build‐up of nutrients or heavy metals in groundwater (or soil) for any plot. Excessive PO43− in the 100% DE plot groundwater is likely due to high background soil P, soil characteristics, and the occurrence of macropore/soil pore flow. These factors (particularly background soil P) should be assessed when determining suitable sites for land‐spreading OBs.