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

Abstract

Emerging remediation technologies such as chemical amendment of dairy cattle slurry have the 29 potential to reduce phosphorus (P) solubility and consequently reduce P losses arising from land 30 application of dairy cattle slurry. The aim of this study was to determine the effectiveness of 31 chemical amendment of slurry to reduce incidental losses of P and suspended sediment (SS) 32 from grassland following application of dairy cattle slurry and to examine the effect of 33 amendments on metal concentrations in runoff water. Intact grassed-soil samples were placed in 34 two laboratory runoff boxes, each 200-cm-long by 22.5-cm-wide by 5-cm-deep, before being 35 amended with dairy cattle slurry (the study control) and slurry amended with either: (i) alum, 36 comprising 8% aluminium oxide (Al2O3) (1.11:1 aluminum (Al):total phosphorus (TP) of slurry) 37(ii) poly-aluminum chloride hydroxide (PAC) comprising 10% Al2O3 (0.93:1 Al:TP) (iii) 38 analytical grade ferric chloride (FeCl2) (2:1 Fe:TP), (iv) and lime (Ca(OH)2) (10:1 Ca:TP). When 39 compared with the study control, PAC was the most effective amendment, reducing dissolved 40 reactive phosphorus (DRP) by up to 86% while alum was most effective in reducing SS (88%), 41 TP (94%), particulate phosphorus (PP) (95%), total dissolved phosphorus (TDP) (8 1%), and 42 dissolved unreactive phosphorus (DUP) (86%). Chemical amendment of slurry did not appear to 43 significantly increase losses of Al and Fe compared to the study control, while all amendments 44 increased Ca loss compared to control and grass-only treatment. While chemical amendments 45 were effective, the reductions in incidental P losses observed in this study were similar to those 46 observed in other studies where the time from slurry application to the first rainfall event was 47 increased. Timing of slurry application may therefore be a much more feasible way to reduce 4 48 incidental P losses. Future work must examine the long-term effects of amendments on P loss to 49 runoff and not only incidental losses. Land application of dairy cattle slurry can result in incidental and chronic phosphorus (P) losses 57 to a waterbody (Buda et al., 2009), which may lead to eutrophication (Carpenter et al., 1998). 58Incidental P losses take place when a rainfall event occurs shortly after slurry application and 59 before slurry infiltrates the soil, while chronic P losses are a long-term loss of P from soil as a 60 result of a build-up in soil test P (STP) caused by application of inorganic fertilisers and manure 61 (Buda et al., 2009). Incidental P losses arising from rainfall events following land application of 62 dairy cattle slurry are the focus of this study. 6364 examined the results of a number of studies examining P losses following 65 land application of dairy cattle slurry at different rates and under different climatic conditions 66 (Smith et al., 2001a;Withers et al., 2001;Withers and Bailey, 2003) and found that incidental P 67 losses can account for between 50 and 90% of P losses from land to w...

Available content, surface runoff and leaching of phosphorus forms in a typic hapludalf treated with organic and mineral nutrient sources

“…This shows that, especially for PL, using N contents for determining P rates might not be the best criterion. The reason is that, after successive manure applications, there was an accumulation of available P in the surface layers and migration in the soil profile, intensifying P transfer via surface runoff (Bertol et al, 2010;Ceretta et al, 2010b;Brennan et al, 2011;Kang et al, 2011) and leaching Girotto et al, 2013), which may cause eutrophication of surface and underground water bodies (Correll, 1998;Smith et al, 2007, Ceretta et al, 2010bHahn et al, 2012).…”

Impact of slurry application method on phosphorus loss in runoff from grassland soils during periods of high soil moisture content

“…Soil moisture levels below or within +2% of field capacity (40.1%) By adhering to these criteria, the following spreading dates were adopted, thus ensuring that measurements encompassed the late winter and early spring periods: 7 December 2009, 18 January 2010, 1 March 2010 and 12 April 2010, with all intervals between spreading dates being 42 days. The runoff plots were established based on the methods detailed in the previous studies, including Brennan et al (2011), O Rourke et al (2012, McConnell et al (2013 a&b), Doody et al (2014) and McConnell et al (2015). Two weeks prior to each slurry application (so as to minimise soil disturbance), a shallow trench was excavated along the down-slope edge of each plot and a stainless steel V-shaped collection tray (0.5 × 0.1 × 0.1 m) placed in the trench to act as a runoff collector.…”

“…Thus the current study clearly demonstrates that during periods of high antecedent soil moisture levels the trailing-shoe technique can be equally effective as during the summer months in reducing the risk of P losses in runoff at this scale. A number of recent studies have examined measures to reducing the risk of P loss following slurry application to grassland soils under Irish conditions (O'Rourke et al, 2010;Brennan et al, 2011;O'Rourke et al, 2012;Serrenho et al, 2012;Murnane et al, 2015). For example, Brennan et al, (2011) reported an 86%, 83%, 69% and 67% reduction in DRP in runoff from soil boxes following the application of slurry amended with ploy-aluminium chloride hydroxide, alum, lime and FeCl 2 , respectively.…”

“…However, in a recent plot scale study by McConnell et al (2013a), dissolved reactive P (DRP) concentrations in runoff were reduced by 37%, following slurry application using the trailing-shoe technique, in comparison to traditional 'splash-plate' spreading. While a small number of studies have examined the use of trailing shoe technology to reduce P loss to water (McConnell et al, 2013a & b), a number of studies have examined the use of a range of other approaches to reducing the risk of P loss post-slurry application (O'Rourke et al, 2010;Brennan et al, 2011;O'Rourke et al, 2012;Murnane et al, 2015). However, unlike the study of Lalor et al (2011Lalor et al ( , 2014, these studies were carried out using small-scale rainfall simulations.…”

“…Rainfall simulation methodologies have provided a useful cost-effective tool for testing hypothesis related a wide range of mitigation strategies (e.g Serrenho et al, 2012;Doody et al, 2014;McConnell et al, 2015). Rourke et al (2012) used rainfall simulation techniques to demonstrate a reduction of P loss in runoff when dairy cows were fed a diet containing reduced P levels, while Brennan et al (2011) used the technique to examine the impact of a range of chemical amendments to slurry on P-suspended sediment and metal loss in runoff from grassland soils. While McConnell et al (2013a) evaluated the use of the trailing shoe to reduce P loss in runoff during the 'summer' months (May/June), the effectiveness of this technique as a means of reducing P losses does not appear to have been tested during periods when soil moisture content is closer to saturation and herbage covers are lower, for example during late winter/early spring.…”