Long-term application of animal slurries to grassland alters soil cation balance |
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Authors: | P.N.C. Murphy R.J. Stevens P. Christie |
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Affiliation: | Department of Agricultural and Environmental Science, Queen's University Belfast, Newforge Lane, Belfast BT9 5PX, UK.;Agriculture, Food and Environmental Science Division, Department of Agriculture and Rural Development, Newforge Lane, Belfast BT9 5PX, UK |
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Abstract: | Abstract. Soil samples from a 32-year grassland field experiment were taken from 0–5, 5–10, and 10–15 cm soil depths in February 2002. Plots received annual treatments of unamended control, mineral fertilizer, three rates of pig slurry and three rates of cow slurry, each with six replicates. Samples were analysed for cation exchange capacity (CEC), exchangeable cations (Na+, K+, Ca2+, Mg2+), pH and Olsen P. Exchangeable sodium percentage (ESP) was calculated as a sodicity indicator. Mean ESP was generally greater for slurry treatments than the control, with a trend of increasing ESP with application rate. This was particularly marked for cow slurry. At 0–5 cm depth ESP increased from 1.18 in the control to 1.75 at the highest rate of pig slurry and 5.60 at the highest rate of cow slurry. Similar trends were shown for CEC, exchangeable Na+, K+ and Mg2+, Ca2+ and Olsen P. The build-up of soil P due to slurry applications, together with this combination of physical and chemical factors, may increase the risk of P loss to surface waters, particularly from soils receiving high rates of cow slurry. |
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Keywords: | Phosphorus sodicity cation exchange capacity phosphorus loss infiltration animal slurry |
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