The loss of phosphorus (P) from agricultural sources is one of the main causes of eutrophication in P-limited freshwater ecosystems. High losses have been shown from grazed grasslands in particular. The aim of this research was to investigate the pools and fluxes of P in grazed grassland in Ireland. This aim was achieved by laboratory characterisation of P forms and fractions in grassland soils and fresh cattle dung, through field trials set up to examine changes in the P content of dung-pats during decomposition and the effects of decomposing dung-pats on soil P fractions, and by the characterisation of P in overland flow from grazed plots using rainfall simulation. Phosphorous 31 nuclear magnetic resonance (31P NMR) spectroscopy analysis revealed the presence of inorganic orthophosphate, orthophosphate monoesters (mostly as myo-inositol hexakisphosphate), orthophosphate diesters (as phospholipids and DNA), and pyrophosphates, in a grassland soil; the relative proportion of these forms in the dung was also dependent on fertiliser P application. Large variation was found in the P characteristics of dung from beef cattle, in particular the proportions of the organic and inorganic fractions, explained mostly by the effect of fertiliser P application. There was a clear relationship between the P content in the diet of the grazing animals and the P content in the dung. The decomposition of dung-pats at different times of year was explained by varying contributions of rainfall, temperature and biological activity, although all dung-pats had decomposed fully within 90 days of deposition. Significant P was released from the dung-pats (between 19 and 31%) during the first seven days of decomposition because of leaching associated with high water losses from the dung-pats. Physical incorporation of the dung-pat was the principal P release mechanism later in the trial. The decomposing dung-pats had highly significant effects on the concentrations of all soil P fractions (total P, inorganic P, microbial biomass P, and Morgan?s P [Pm]) except for the organic P fraction. Pm concentrations increased by between 200 and 450% owing to the presence of dung-pats. The presence of grazing animals increased the concentrations of organic P lost to overland flow. 31P NMR spectroscopy analysis revealed the presence of inorganic orthophosphate, orthophosphate monoesters, orthophosphate diesters, phosphonates, and pyrophosphates in the overland flow from grazed plots, while only inorganic orthophosphate, orthophosphate monoesters, and pyrophosphates were found in the overland flow from non-grazed plots. These results offer insights into the P dynamics within grazed grassland and the potential P losses from grazed grassland.

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Bourke, D. Kurz, I. Tunney, H.   "Eutrophication from Agricultural Sources : Phosphorus Dynamics in Grazed Grassland". Associated datasets and digitial information objects connected to this resource are available at: Secure Archive For Environmental Research Data (SAFER) managed by Environmental Protection Agency Ireland https://eparesearch.epa.ie/safer/resource?id=513e1727-74a4-102b-aa08-55a7497570d3 (Last Accessed: 2025-01-16)

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SAFER-Data Display URL	https://eparesearch.epa.ie/safer/iso19115/display?isoID=68
Resource Keywords	Phosphorus Nitrogen Eutrophication Potassium Suspended Solids Grazed Pastures
EPA/ERTDI/STRIVE Project Code	2000-LS-2.1.2c-M2
EPA/ERTDI/STRIVE Project Theme	Water Quality
Resource Availability:	Public-Open
Limitations on the use of this Resource	Later on...
Number of Attached Files (Publicly and Openly Available for Download):	2
Project Start Date	Thursday 1st August 2002 (01-08-2002)
Earliest Recorded Date within any attached datasets or digital objects	Thursday 1st August 2002 (01-08-2002)
Most Recent Recorded Date within any attached datasets or digital objects	Saturday 31st July 2004 (31-07-2004)
Published on SAFER	Friday 16th May 2008 (16-05-2008)
Date of Last Edit	Friday 16th May 2008 at 15:41:37 (16-05-2008)
Datasets or Files Updated On	Friday 16th May 2008 at 15:41:37 (16-05-2008)

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Description of Geographical Characteristics of This Project or Dataset
The three study sites (Cowlands, Red House Field and Dairy Farm) were located at the Teagasc Environmental Research Centre, Johnstown Castle, Wexford, Ireland (302404/116584 UTM) at an altitude of 60?70 m above sea level. The research centre covers an area of about 390 ha with the three sites located less than 1.5 km from a meteorological station. The land use of the three sites was set up as permanent pasture. Mean annual rainfall during the experimental period was 1032 mm with a mean annual temperature of 10.6 oC as measured at the meteorological station.

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The following is a list of projects, datasets, and resources on SAFER-Data from which users downloaded attachments from soon after downloading attachments from this resource Eutrophication from Agricultural Sources : Phosphorus Dynamics in Grazed Grassland. You can view the full description for projects, datasets, and resources by using the links supplied.

• Eutrophication From Agricultural Sources - Soil and Phosphorus: Catchment Studies View Full Metadata Description
• Phosphorus, Nitrogen and Suspended Sediment loss from Soil to Water from Agricultural Grassland View Full Metadata Description
• Foresty Operations and Eutrophication - The Influence of Forestry and Forest Operations on Water (PEnrich) View Full Metadata Description
• A Framework for the Assessment of Groundwater - Dependent Terrestrial Ecosystems under the Water Framework Directive View Full Metadata Description
• Water Framework Directive: Recharge and Groundwater Vulnerability View Full Metadata Description

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