Nitrate leaching in agriculture to upper groundwater in the sandy regions of the Netherlands during the 1992-1995 period

We found here that a reduction in nitrate leaching of more than 20% in future would almost certainly be detected with the LMM. Detecting downward trends due to decreasing N load will require nitrate concentrations to also be related to soil drainage, precipitation excess leading to groundwater recharge and to location. Furthermore, we found that about 16% of the N load in the Dutch sandy regions was being leached to the upper metre of groundwater in the 1992–1995 period. The critical N load in approximately 1990 for exceeding the EC limit value for nitrate, NO3, (50 mg L−1) in the upper metre of groundwater for the mean situation for grassland, maize and arable land in the sandy area was found to be 210 kg ha−1 a−1. Because manure management has been altered, the critical load found will be lower than the current critical load .