Nitrogen in Water-Portugal and Denmark: Two Contrasting Realities
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water Review Nitrogen in Water-Portugal and Denmark: Two Contrasting Realities Soraia Cruz 1,*, Cláudia M.d.S. Cordovil 1, Renata Pinto 1, António G. Brito 1 , Maria R. Cameira 1 , Guilherme Gonçalves 1, Jane R. Poulsen 2, Hans Thodsen 2, Brian Kronvang 2 and Linda May 3 1 School of Agriculture, University of Lisbon, LEAF—Linking Landscape, Environment, Agriculture and Food, Tapada da Ajuda, 1349-017 Lisbon, Portugal; [email protected] (C.M.d.S.C.); [email protected] (R.P.); [email protected] (A.G.B.); [email protected] (M.R.C.); [email protected] (G.G.) 2 Department of Biosciences, University of Aarhus, Vejlsovej 25, 8600 Silkeborg, Denmark; [email protected] (J.R.P.); [email protected] (H.T.); [email protected] (B.K.) 3 Centre for Ecology & Hydrology, Edinburgh, Bush Estate, Penicuik, Midlothian EH26 0QB, UK; [email protected] * Correspondence: [email protected]; Tel.: +351-913-507-286 Received: 11 March 2019; Accepted: 4 May 2019; Published: 28 May 2019 Abstract: Agricultural activities are responsible for most of the nitrogen (N) inputs that degrade water quality. To elucidate the drivers leading to N pressures on water, we examined the resulting state of surface waters in terms of N concentrations, the impact of this on water quality status and policy responses to these constraints across different climatic and management conditions. Portugal and Denmark were chosen as contrasting case studies for the Driver-Pressure-State-Impact-Response (DPSIR) analysis. Our results showed reductions of 39% and 25% in the use of mineral fertilizer in Portugal and Denmark, respectively, between 2000 and 2010. The N surplus in Portugal varied 1 between 15 and 30 kg N ha− between 1995 and 2015. In Denmark, in 2015, this amount was 70 kg N 1 ha− , representing a 53% decrease from the 1990 value. The average amount of total N discharged to 1 1 surface waters was 7 kg ha− for mainland Portugal in 2015 and 14.6 kg ha− for Denmark in 2014. These reductions in the N surplus were attributed to historical policies aimed at N pressure abatement. In Denmark, N losses are expected to decline further through the continuation or improvement of existing national action plans. In Portugal, they are expected to decline further due to the expansion of Nitrate Vulnerable Zones and the introduction of targeted policies aimed at improving N use efficiency and reducing losses to water. Keywords: agricultural intensification; DPSIR; nitrogen; pressures; policies; surface water pollution 1. Introduction On many occasions, agriculture has been highlighted as a major contributor to nitrogen (N) pollution to water, although the livestock and urban sectors are important contributors as well. The low use efficiency of N applied as chemical fertilizers and manures leads to a N surplus that can be lost to ground and surface waters, reducing their quality and putting pressure onto receiving waterbodies [1]. Indeed, the European Environmental Agency [2] reported that pollution pressures from diffuse sources (especially agriculture) were affecting 30% to 50% of surface waters in the European Union (EU). However, the negative impacts of N inputs to water from agricultural sources vary across the EU due to significant spatial differences in climate, soil types, geology, topography, and agricultural management activities. In many cases, natural conditions determine land use, N attenuation and, hence, potential N losses [3]. European crop and livestock farms have increased their productivity in recent decades, Water 2019, 11, 1114; doi:10.3390/w11061114 www.mdpi.com/journal/water Water 2019, 10, x FOR PEER REVIEW 2 of 21 Waterthe case2019, 11in, 1114the two countries under study, which have contrasting agricultural systems 2[6,7]. of 20 Agriculture accounts for approximately 47% of the land use in mainland Portugal [8] and about 60% in Denmark. contributingDenmark, to one the levelof the water most intensively contamination farmed by nitrates countries [4, 5in]. Europe This is [9], the became case in theaware two at countries an early understage that study, nutrient which emissions have contrasting from diffuse agricultural sources, systems especially [6,7]. in Agriculture agricultural accounts areas, were for approximately causing algal 47%blooms of theand land promoting use in mainland hypoxia in Portugal coastal [waters8] and [10,11]. about 60% Since in 1985, Denmark. the negative impacts of nutrient loadsDenmark, to water in one Denmark of the most have intensively triggered a farmed series of countries “nutrient in action Europe plans” [9], became such as aware the designation at an early stageof the that whole nutrient country emissions as a Nitrate from di ffVulnerableuse sources, Zo especiallyne (NVZ). in agriculturalThese have areas, significantly were causing improved algal bloomsagricultural and promotingN use efficiency hypoxia and in reduced coastal watersN leaching, [10,11 even]. Since though 1985, animal the negative production impacts has of increased nutrient loads[12]. to water in Denmark have triggered a series of “nutrient action plans” such as the designation of the wholeIn contrast, country Portugal as a Nitrate has extensive Vulnerable areas Zone of (NVZ). its land These (~86%) have under significantly agricultural improved use. However, agricultural the Nimplementation use efficiency andof the reduced Nitrates N Directive leaching, even(ND) thoughwas not animal translated production into NVZ has designation increased [12 until]. 1998, with Inonly contrast, 4% of the Portugal territory has included extensive by areas2012. ofLocal its landfactors (~86%) controlling under nitrate agricultural leaching use. are However, the high thetemperatures implementation during ofhalf the of Nitrates the year Directive that promote (ND) the was volatilization not translated of N into and NVZ reduce designation losses to water until 1998,[13]. On with the only other 4% ofhand, the territory alternating included dry byand 2012. wet Localsoil conditions factors controlling stimulate nitrate soil leachingorganic arematter the highmineralization temperatures and duringpromote half nitrate of the leaching year that from promote minerali thezed volatilization nitrogen compounds of N and reduce[14]. losses to waterThe [13 ].main On theobjective other hand,of this alternating paper is to dry compare and wet how soil the conditions current stimulateN pressures soil organicmay affect matter the mineralizationenvironmental andstate promote and water nitrate quality leaching in two from cont mineralizedrasting countries, nitrogen Portugal compounds and[ 14Denmark.]. This paperThe also main hypothesizes objective of that this paperdifferent is topolicie compares, and how their the currentimplementation, N pressures have may influenced affect the environmentalagricultural N state pressures and water and, quality consequently, in two contrasting the environmental countries, Portugal condition and Denmark. of water This and paper the alsoeffectiveness hypothesizes of various that di mitigationfferent policies, measures and theirthat have implementation, been implemented have influenced to reduce agriculturalN losses from N pressuresagriculture and, in both consequently, countries. Although the environmental knowledg conditione exists already of water about and water the e ffrelatedectiveness environmental of various mitigationissues in Portugal measures and that Denmark, have been there implemented has been tono reduce focused N lossescomparison from agriculture between these in both contrasting countries. Althoughcountries knowledgein terms of existsimpacts already on water about quality water and related policy environmental responses. issues in Portugal and Denmark, there has been no focused comparison between these contrasting countries in terms of impacts on water2. Materials quality and and Methods policy responses. 2. MaterialsA brief anddescription Methods of the main differences between Denmark and Portugal, in terms of agriculture and livestock production, urban pressures, water monitoring systems, climate, policy responses,A brief etc., description is essential of the to main understand differences better between the causes Denmark of andwater Portugal, qualityin degradation terms of agriculture in each andcountry. livestock Figure production, 1 shows where urban the pressures, case studies, water Po monitoringrtugal and systems, Denmark, climate, are in policy Europe, responses, and the etc., main is essentialdifferences to understandbetween these better countries the causes are of presented water quality below. degradation The data in used each for country. the analysis Figure1 in shows each wherecountry the was case obtained studies, from Portugal the respective and Denmark, National are in Statistics Europe, Institutions. and the main differences between these countries are presented below. The data used for the analysis in each country was obtained from the respective2.1. Site Study—Brief National Statistics Characterization Institutions. of the Countries Figure 1. Location of Portugal (PT) and Denmark (DK) in Europe. Water 2019, 11, 1114 3 of 20 2.1. Site Study—Brief Characterization of the Countries The mainland of Portugal (89,060 km2) is in the south-west of the Iberian Peninsula (Figure1); it also has two major archipelagos, the Azores (2333 km2) and Madeira (801 km2). Only the mainland, which borders Spain (north and east) and the Atlantic Ocean (south and west), was considered in this study. A Mediterranean climate, characterized by hot, dry summers and cool,