on and loss to from

Emerging remediation technologies such as chemical amendment of dairy cattle slurry have the 28 potential to reduce phosphorus (P) solubility and consequently reduce P losses arising from land 29 application of dairy cattle slurry. The aim of this study was to determine the effectiveness of 30 chemical amendment of slurry to reduce incidental losses of P and suspended sediment (SS) 31 from grassland following application of dairy cattle slurry and to examine the effect of 32 amendments on metal concentrations in runoff water. Intact grassed-soil samples were placed in 33 two laboratory runoff boxes, each 200-cm-long by 22.5-cm-wide by 5-cm-deep, before being 34 amended with dairy cattle slurry (the study control) and slurry amended with either: (i) alum, 35 comprising 8% aluminium oxide (Al 2 O 3 ) (1.11:1 aluminum (Al):total phosphorus (TP) of slurry) 36 (ii) poly-aluminum chloride hydroxide (PAC) comprising 10% Al 2 O 3 (0.93:1 Al:TP) (iii) 37 analytical grade ferric chloride (FeCl 2 ) (2:1 Fe:TP), (iv) and lime (Ca(OH) 2 ) (10:1 Ca:TP). When 38 compared with the study control, PAC was the most effective amendment, reducing dissolved 39 reactive phosphorus (DRP) by up to 86% while alum was most effective in reducing SS (88%), 40 TP (94%), particulate phosphorus (PP) (95%), total dissolved phosphorus (TDP) (81%), and 41 dissolved unreactive phosphorus (DUP) (86%). Chemical amendment of slurry did not appear to 42 significantly increase losses of Al and Fe compared to the study control, while all amendments 43 increased Ca loss compared to control and grass-only treatment. While chemical amendments 44 were effective, the reductions in incidental P losses observed in this study were similar to those 45 observed in other studies where the time from slurry application to the first rainfall event was 46 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 48 runoff and not only incidental losses.

[1]  Chemisorption and Precipitation Reactions , 2018, Handbook of Soil Sciences (Two Volume Set).

[2]  R. Harmel,et al.  Impact of soil amendments on reducing phosphorus losses from runoff in sod. , 2005, Journal of environmental quality.

[3]  Christian Stamm,et al.  Incidental phosphorus losses – are they significant and can they be predicted? , 2003 .

[4]  P. Withers,et al.  Sediment and phosphorus transfer in overland flow from a maize field receiving manure , 2003 .

[5]  Andrew N. Sharpley,et al.  Effect of plot scale and an upslope phosphorus source on phosphorus loss in overland flow , 2002 .

[6]  J. Meisinger,et al.  Effect of adding alum or zeolite to dairy slurry on ammonia volatilization and chemical composition. , 2001, Journal of dairy science.

[7]  T. C. Daniel,et al.  Effects of alum and aluminum chloride on phosphorus runoff from swine manure. , 2001, Journal of environmental quality.

[8]  J. T. Regan,et al.  Determining phosphorus and sediment release rates from five Irish tillage soils. , 2010, Journal of environmental quality.

[9]  A. Sharpley.  Assessing phosphorus bioavailability in agricultural soils and runoff , 2004, Fertilizer research.

[10]  H. D. Stensel,et al.  Wastewater Engineering: Treatment and Reuse , 2002 .

[11]  H. Tunney,et al.  Phosphorus needs of grassland soils and loss to water. , 2002 .

[12]  D. R. Jackson,et al.  Nutrient losses by surface run-off following the application of organic manures to arable land. 2. Phosphorus. , 2001, Environmental pollution.

[13]  David B. Parker,et al.  SURFACE AMENDMENTS TO MINIMIZE AMMONIA EMISSIONS FROM BEEF CATTLE FEEDLOTS , 2001 .

[14]  P. Withers,et al.  Phosphorus transfer in runoff following application of fertilizer, manure, and sewage sludge. , 2001, Journal of environmental quality.

[15]  John D. Williams,et al.  A NEW RAINFALL SIMULATOR FOR USE IN LOW-ENERGY RAINFALL AREAS , 1998 .

[16]  H. Tunney.  A Note on a Balance Sheet Approach to Estimating the Phosphorus Fertiliser Needs of Agriculture , 1990 .