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

Abstract

Abstract. 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][2008][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 Nefficient 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 Published by Copernicus Publications on behalf of the European Geosciences Union. T. Dalgaard et al.: Farm nitrogen balances as indicator for nitrogen lossesmethod was thus effective for comparing and synthesizing results on farm N emissions and the potentials of miti...

Nitrogen soil surface balance of organic vs conventional cash crop farming in the Seine watershed

“…Specifically regarding OF, most studies in EU used farm gate balance method to examine N surplus/deficit and N use efficiency in mixed crop and livestock farms, mainly dairies. They show varying results depending in particular on livestock density and the estimation of biological nitrogen fixation from legumes fodders and crops (Dalgaard et al, 2012;Nielsen and Kristensen, 2005;Steinshamn et al, 2004;Watson et al, 2002b;Cederberg and Mattsson, 2000;Simon et al, 2000;Halberg et al, 1995). Studies comparing organic and conventional systems via the SSB method are scarce but they tend to show that OF systems had the lowest soil N surplus (even sometimes negative indicating soil depletion or an underestimation of nitrogen fixation) and a better N use efficiency in comparison with the CF systems (Migliorini et al, 2014;Blesh and Drinkwater, 2013;Berry et al, 2003;Eltun et al, 2002).…”

Nitrogen flows on organic and conventional dairy farms: a comparison of three indicators

“…For example, one common indicator is the N surplus (N input -N output), which is often reported per unit cropland area (Nevens et al 2006;Oenema 2006;Dalgaard et al 2012), and sometimes per unit product (Dalgaard et al 1998;Schröder et al 2003;Mihailescu et al 2014;Mu et al 2016), or inversely, as product quantity per unit N surplus (''eco-efficiency'', Nevens et al 2006;Beukes et al 2012). Another indicator often constructed from farm-gate N budgets is the N use efficiency (NUE), defined as N output/N input (Schröder et al 2003;Godinot et al 2014;Gerber et al 2014).…”

Potential for biological nitrification inhibition to reduce nitrification and N2O emissions in pasture crop–livestock systems

“…In addition, several heterotrophic soil bacteria denitrify NO 3 2 under anaerobic or partially anaerobic conditions (which can often coincide with temporary water-logging of a soil after a heavy rainfall or irrigation in fields that have improper drainage; Bremner and Blackmer, 1978;Mosier et al, 1996). The loss of nitrogen (N) during and following nitrification reduces the effectiveness of N fertilization, causing environmental degradation, loss of biodiversity, loss of ecosystem services, emergence of pathogens and threatening the long-term sustainability of agricultural production systems (Clark, 1962;Jarvis, 1996;Vitousek et al, 1997a and1997b;Dalgaard et al, 2012).…”