Abstract

In a catchmnent, nitrogen (N) export from terrestrial ecosystems to rivers is controlled by the hydrologicalprocesses and N balance. In the present paper, the soil system N budget and riverine exportwere quantified in a Mediterranean watershed, the Celone (South-East, Italy). The study area (72 km2)consists of agricultural land (70%) and deciduous forests with three small residential areas. Major Ninputs derived from fertilizers and animal manure, corresponding for the whole watershed area to 68and 12 kg N ha-1 yr-1, respectively. N input from point sources was 1% of total input and atmosphericdepositions measured in a gauging station near the study area was quantified in ~6 kg N ha-1 yr-1. CropN uptake was the main N output from agricultural land; it was estimated in ~37 kg N ha-1 yr-1 by usingdata on crop yields provided by local farmers. Total flux of N in surface water was quantified for a year atthe outlet of the study area by using continuous measures of flow and discrete measures of N concentrationscarried 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 concentrationsand loads. Riverine N export was quantified in 41% of total N input, and it was mainly transported duringflood events, ~60% of the annual load was delivered during floods occurred in 38 days. Organic nitrogenand nitrate were the main N forms in surface water, and the contribution per hectare was about24 and 14 kg N, respectively. On a yearly basis, the difference between N inputs and outputs includingriverine export was estimated in about 4 kg N ha-1 yr-1 for the whole watershed area. This amount partlyaccumulates in soils in different N forms and the remaining part, mainly in form of nitrate, percolatesthrough unsaturated soiltowards groundwater. This study reports an important analysis of N pollution ina Mediterranean watershed with a temporary river system and limited data availability. Data acquisitionand handling have proved to be an important challenge to overcome in N balance quantification. Theresults and the methodology of the present work can be useful for understanding nitrogen loss dynamicsand for functional water management and land use planning.

Autore Pugliese

• De Girolamo Anna Maria , Lo Porto Antonio , Pappagallo Giuseppe

Tutti gli autori

• De Girolamo A.M.; Balestrini R.; D'Ambrosio E.; Pappagallo G.; Soana E.; Lo Porto A.

Titolo volume/Rivista

Agricultural water management

Anno di pubblicazione

2017

ISSN

0378-3774

ISBN

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Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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