References

Biogeosciences

1726-4189

Copernicus Publications

Göttingen, Germany

10.5194/bg-9-5303-2012

Farm nitrogen balances in six European landscapes as an indicator for nitrogen losses and basis for improved management

Dalgaard

¹ Bienkowski

J. F.

² Bleeker

³ Dragosits

⁴ Drouet

J. L.

⁵ Durand

⁶ Frumau

³ Hutchings

N. J.

¹ Kedziora

² Magliulo

https://orcid.org/0000-0001-5505-6552

⁷ Olesen

J. E.

¹ Theobald

M. R.

⁴ ⁸ Maury

⁵ Akkal

⁶ Cellier

⁴

Aarhus University, Department of Agroecology, Denmark

Institute for Agricultural and Forest Environment, Poland

Energy Research Centre of the Netherlands, The Netherlands

Centre for Ecology and Hydrology, Scotland, UK

INRA, Environnement et Grandes Cultures, France

INRA, Soil, Agro-hydrosystems Spatialisation, France

Institute for Agriculture and Forest Systems in the Mediterranean, Italy

Technical University of Madrid, Spain

20 12 2012

9 12 5303 5321

2012

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://bg.copernicus.org/articles/9/5303/2012/bg-9-5303-2012.html

The full text article is available as a PDF file from https://bg.copernicus.org/articles/9/5303/2012/bg-9-5303-2012.pdf

Improved management of nitrogen (N) in agriculture is necessary to achieve a sustainable balance between the production of food and other biomass, and the unwanted effects of N on water pollution, greenhouse gas emissions, biodiversity deterioration and human health. To analyse farm N-losses and the complex interactions within farming systems, efficient methods for identifying emissions hotspots and evaluating mitigation measures are therefore needed. The present paper aims to fill this gap at the farm and landscape scales. Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm N balances, N surpluses and for evaluating uncertainty for the 222 farms and 11 440 ha of farmland included in the study. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202 ± 28, 179 ± 63 and 178 ± 20 kg N ha−1 yr−1, respectively. All landscapes showed hotspots, especially from livestock farms, including a special UK case with large-scale landless poultry farming. Overall, the average N surplus from the land-based UK farms dominated by extensive sheep and cattle grazing was only 31 ± 10 kg N ha−1 yr−1, but was similar to the N surplus of PL and DK (122 ± 20 and 146 ± 55 kg N ha−1 yr−1, respectively) when landless poultry farming was included. We found farm N balances to be a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate concentrations in soils and groundwater, measured during the period of N management data collection in the landscapes from 2007–2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. No significant correlation was found with N measured in surface waters, probably because of spatial and temporal variations in groundwater buffering and biogeochemical reactions affecting N flows from farm to surface waters. A case study of the development in N surplus from the landscape in DK from 1998–2008 showed a 22% reduction related to measures targeted at N emissions from livestock farms. Based on the large differences in N surplus between average N management farms and the most modern and N-efficient farms, it was concluded that additional N-surplus reductions of 25–50%, as compared to the present level, were realistic in all landscapes. The implemented N-surplus method was thus effective for comparing and synthesizing results on farm N emissions and the potentials of mitigation options. It is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed N source and N sink hotspot mapping, measurements and modelling.

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