Marianne Bechmann, Inga Greipsland, Hugh Riley, Hans Olav Eggestad
The current IPCC guidelines define an estimate for the fraction of mineral fertilizer and animal waste
(manure) lost to leaching and runoff (FracLEACH). The FracLEACH default is 30 %. In Norway, 18 % has
been used based on calculations made in 1998 (Vagstad et al. , 1998).
The main purpose of this study was to give an updated estimate of nitrogen (N) leaching in relation to
the amounts of N applied in agriculture (FracLEACH). The term losses in this report include both
surface and subsurface runoff.
The estimates of FracLEACH presented in this report were based on data from the Agricultural
Environmental monitoring program (JOVA). The JOVA-program includes catchment and field study sites
representing typical situations in Norwegian agriculture with regard to production system,
management, intensity, soil, landscape, region and climate. Data from plot- scale study sites
confirmed the level of N leaching from the agricultural areas within the JOVA catchments.