Agricultural Water Management 187 (2017) 190–199 Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat Research paper Antropogenic input of nitrogen and riverine export from a Mediterranean catchment. The Celone, a temporary river case study Anna Maria De Girolamo a,∗ , Raffaella Balestrini b , Ersilia D’Ambrosio a,c , Giuseppe Pappagallo a , Elisa Soana d , Antonio Lo Porto a a Water Research Institute, National Research Council, Bari, Italy b Water Research Institute, National Research Council, Brugherio, MI, Italy c Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy d Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy a r t i c l e i n f o Article history: Received 30 September 2016 Received in revised form 17 March 2017 Accepted 21 March 2017 Keywords: N balance N export Point and non point sources of N Mediterranean catchment Temporary river a b s t r a c t In a catchmnent, nitrogen (N) export from terrestrial ecosystems to rivers is controlled by the hydro- logical processes and N balance. In the present paper, the soil system N budget and riverine export were quantified in a Mediterranean watershed, the Celone (South-East, Italy). The study area (72 km 2 ) consists of agricultural land (70%) and deciduous forests with three small residential areas. Major N inputs derived from fertilizers and animal manure, corresponding for the whole watershed area to 68 and 12 kg N ha −1 yr −1 , respectively. N input from point sources was 1% of total input and atmospheric depositions measured in a gauging station near the study area was quantified in ∼6 kg N ha −1 yr −1 . Crop N uptake was the main N output from agricultural land; it was estimated in ∼37 kg N ha −1 yr −1 by using data on crop yields provided by local farmers. Total flux of N in surface water was quantified for a year at the outlet of the study area by using continuous measures of flow and discrete measures of N concentra- tions carried out with a different frequency during the normal and low flow and when floods occurred. The hydrological regime of the stream, which is a temporary river, plays an important role in N transport. Water quality was found to vary considerably through the year in terms of both nutrient concentrations and loads. Riverine N export was quantified in 41% of total N input, and it was mainly transported during flood events, ∼60% of the annual load was delivered during floods occurred in 38 days. Organic nitro- gen and nitrate were the main N forms in surface water, and the contribution per hectare was about 24 and 14 kg N, respectively. On a yearly basis, the difference between N inputs and outputs including riverine export was estimated in about 4 kg N ha −1 yr −1 for the whole watershed area. This amount partly accumulates in soils in different N forms and the remaining part, mainly in form of nitrate, percolates through unsaturated soil towards groundwater. This study reports an important analysis of N pollution in a Mediterranean watershed with a temporary river system and limited data availability. Data acquisition and handling have proved to be an important challenge to overcome in N balance quantification. The results and the methodology of the present work can be useful for understanding nitrogen loss dynamics and for functional water management and land use planning. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Over the past 50 years, agricultural practices have changed sig- nificantly. The intensive agriculture led to an increase in food and non-food productions, but at a high environmental cost (Tilman et al., 2002). As a result of the excess of pesticides and fertilizers, a decrease in biodiversity of natural areas, an impairment of sur- ∗ Corresponding author. E-mail addresses: annamaria.degirolamo@ba.irsa.cnr.it, annamaria.degirolamo@gmail.com (A.M. De Girolamo). face waters ecosystems (Boyer et al., 2006), and a contamination of groundwater occurred in many areas (Capri et al., 2009; Wick et al., 2012; Sacchi et al., 2013). Several studies report nutrient surplus due to agricultural activ- ities and breeding livestock (Bassanino et al., 2007; Grizzetti et al., 2008; Bartoli et al., 2012) and an alteration in the natural cycle of nitrogen and phosphorus (Grizzetti et al., 2012). A large nitro- gen (N) input-output imbalance occurs in agricultural lands and nutrient surpluses are generally found in all industrialized coun- tries (Organisation for Economic Co-operation and Development, 2008). In tropical areas, Vitousek et al. (2009) found that more than 80% of fertilizer nitrogen applied in agriculture did not make it http://dx.doi.org/10.1016/j.agwat.2017.03.025 0378-3774/© 2017 Elsevier B.V. All rights reserved.