Best management practices to reduce nitrate pollution in a rural watershed in Germany

Cristiano Andre Pott,Nicola Fohrer

doi:10.4136/ambi-agua.2099

Abstract

Water pollution by nitrogen originates at diffuse and point sources. In surface aquatic systems, nitrate is one of the most problematic forms of nitrogen, causing phytoplankton and macrophyte growth and consequently water eutrophication. This study evaluated whether the Soil and Water Assessment Tool (SWAT) model can simulate nitrate load in a rural watershed in daily and monthly time increments. The study investigated 462 km² of the upper part of the Stör catchment, a typical rural lowland catchment located in Northern Germany. The results showed that simulations of nitrate load at monthly increments are better predictors of observed data than daily simulations. The most effective practices to minimize the NO3-N load were the reduction of nitrogen fertilizer application and the increasing of conservation areas, such as field filter strips.

Highlights

Water pollution problems have been encountered all over the world in the last decades
The most important statistical index parameters used in this study to evaluate the performance of the Soil and Water Assessment Tool (SWAT) model were the Coefficient of determination (R2), the Nash-Sutcliffe efficiency (NSE) and the Percent bias (PBIAS)
According to Moriasi et al (2007), these results indicated a performance ranging from good to very good for NO3-N modeling with the SWAT model

Summary

INTRODUCTION

Water pollution problems have been encountered all over the world in the last decades. Nutrients enter surface waters through point or diffuse sources (Jamshidi et al, 2010; Lam et al, 2010; Merseburger et al, 2011). Fertilizer management is one way to reduce nutrient loads in surface water bodies (Pieterse et al, 2003). Public policies aim to change agricultural practices by supporting land use and management practices that limit the risks of N transfers to streams. These practices are called environment-friendly or best management practices (BMPs), and consist of catch crops, reduced fertilization, conversion of arable land to pasture, grass filter strips, no tillage and conservation tillage systems (Laurent and Ruelland, 2011). This study sought to calibrate and validate nitrate load using the SWAT model to verify which environmental measures can reduce N loads in a rural lowland catchment

MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS