N leaching to groundwater from dairy production involving grazing over the winter on a clay-loam soil

Necpalova, M. and Fenton, O. and Casey, I. and Humphreys, J. (2012) N leaching to groundwater from dairy production involving grazing over the winter on a clay-loam soil. Science of the Total Environment, 432. pp. 159-172. ISSN 0048-9697

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Abstract

This study investigated concentrations of various N species in shallow groundwater (<2.2m below ground level) and N losses from dairy production involving grazing over the winter period on a clay loam soil with a high natural attenuation capacity in southern Ireland (52°51'N, 08°21'W) over a 2-year period. A dense network of shallow groundwater piezometers was installed to determine groundwater flow direction and N spatial and temporal variation. Estimated vertical travel times through the unsaturated zone (<0.5yr, time lag) allowed the correlation of management with groundwater N within a short space of time. There was a two way interaction of the system and sampling date (P<0.05) on concentrations of DON, oxidised N and NO3--N. In contrast, concentrations of NH4+-N and NO2--N were unaffected by the dairy system. Grazing over the winter had no effect on N losses to groundwater. Mean concentrations of DON, NH4+-N, NO2--N and NO3--N were 2.16, 0.35, 0.01 and 0.37mgL-1 respectively. Soil attenuation processes such as denitrification and DNRA resulted in increased NH4+-N levels. For this reason, DON and NH4+-N represented the highest proportion of N losses from the site. Some of the spatial and temporal variation of N concentrations was explained by correlations with selected chemical and hydro-topographical parameters (NO3--N/Cl- ratio, distance of the sampling point from the closest receptor, watertable depth, depth of sampling piezometer, DOC concentration). A high explanatory power of NO3--N/Cl- ratio and the distance of the sampling point from the closest receptor indicated the influence of point sources and groundwater-surface water interactions.

Item Type:	Article
Additional Information:	Funding Information: We would like to thank Kevin McNamara, Bill Keogh (Teagasc Moorepark) and Solohead farm staff for their assistance with the water sampling and Denis Brennan (Teagasc Johnstown Castle) for the laboratory work. Research was supported by the department of Department of Agriculture, Fisheries and Food (Project RSF07-511).
Uncontrolled Keywords:	/dk/atira/pure/subjectarea/asjc/2300/2305
Departments or Groups:
Depositing User:	Admin SSL
Date Deposited:	19 Oct 2022 23:01
Last Modified:	07 Jun 2023 18:41
URI:	http://repository-testing.wit.ie/id/eprint/3609

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