Nutrient losses from subsurface drainage systems in Latvia

Artificial subsurface drainage systems are a common water management practice to remove excess water from agricultural land in the Baltic and Nordic countries. Unfortunately, these systems also serve as nutrient transport pathways from agricultural fields to downstream waterbodies. The objective of this study was to determine the status of subsurface drainage water in the context of implementation of the European Union (EU) Water Framework Directive (WFD) and EU Nitrate Directive (ND), to investigate the impact of hydrology and mineral fertilizer application on nutrient losses through subsurface drainage systems and to evaluate the possible effects of climate change on drainage and nutrient loss. This research was conducted from 1995 through 2013 at the agricultural run-off–monitoring sites in Berze and Mellupite. Continuous-flow measurement data and composite water samples were collected on a monthly basis for assessment of total nitrogen (TN), nitrate–nitrogen (NO3–N) and total phosphorus (TP) in draina...