Impact of chemical amendment of dairy cattle slurry on phosphorus, suspended sediment and metal loss to runoff from a grassland soil

• Published in: The Science of the total environment 2011-11, Vol.409 (23), p.5111-5118
• Main Authors: Brennan, R.B., Fenton, O., Grant, J., Healy, M.G.
• Format: Article
• Language: English
• Subjects: agricultural runoff; Agriculture, rearing and food industries wastes; Agronomy. Soil science and plant productions; alum; Alum Compounds; Aluminum; Aluminum Hydroxide; Aluminum oxide; Animals; application timing; Applied sciences; Biological and medical sciences; calcium; Calcium - analysis; Calcium Compounds; calcium hydroxide; Cattle; cattle manure; Chemical amendment; Chlorides; Dairy; dairy cattle; Dissolution; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Ferric Compounds; Fertilizers - analysis; Fundamental and applied biological sciences. Psychology; Geologic Sediments - analysis; grassland soils; Grasslands; iron; land application; long term effects; losses from soil; Management; Manure - analysis; Metals, Heavy - analysis; Natural water pollution; Oxides; Phosphorus; Phosphorus - analysis; Pollution; Pollution, environment geology; rain; Rainwaters, run off water and others; remediation; Runoff; sediments; Slurries; Slurry; soil amendments; Soil and water pollution; Soil science; solubility; Wastes; Water Pollutants, Chemical - analysis; Water treatment and pollution
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2011.08.016

Emerging remediation technologies such as chemical amendment of dairy cattle slurry have the potential to reduce phosphorus (P) solubility and consequently reduce P losses arising from land application of dairy cattle slurry. The aim of this study was to determine the effectiveness of chemical amendment of slurry to reduce incidental losses of P and suspended sediment (SS) from grassland following application of dairy cattle slurry and to examine the effect of amendments on metal concentrations in runoff water. Intact grassed-soil samples were placed in two laboratory runoff boxes, each 200-cm-long by 22.5-cm-wide by 5-cm-deep, before being amended with dairy cattle slurry (the study control) and slurry amended with either: (i) alum, comprising 8% aluminium oxide (Al 2O 3) (1.11:1 aluminium (Al):total phosphorus (TP) of slurry) (ii) poly-aluminium chloride hydroxide (PAC) comprising 10% Al 2O 3 (0.93:1 Al:TP) (iii) analytical grade ferric chloride (FeCl 2) (2:1 Fe:TP), (iv) and lime (Ca(OH) 2) (10:1 Ca:TP). When compared with the study control, PAC was the most effective amendment, reducing dissolved reactive phosphorus (DRP) by up to 86% while alum was most effective in reducing SS (88%), TP (94%), particulate phosphorus (PP) (95%), total dissolved phosphorus (TDP) (81%), and dissolved unreactive phosphorus (DUP) (86%). Chemical amendment of slurry did not appear to significantly increase losses of Al and Fe compared to the study control, while all amendments increased Ca loss compared to control and grass-only treatment. While chemical amendments were effective, the reductions in incidental P losses observed in this study were similar to those observed in other studies where the time from slurry application to the first rainfall event was increased. Timing of slurry application may therefore be a much more feasible way to reduce incidental P losses. Future work must examine the long-term effects of amendments on P loss to runoff and not only incidental losses. ► We examine chemical amendment of slurry to reduce P and SS losses following application of slurry. ► It examines the effect of amendments on metal concentrations in runoff water. ► Chemical amendments reduced DRP, TP, TDP and DUP by up to 86, 94, 89, and 92%.