English Abstract In 1992 a three-year monitoring program was started to
assess the quality of the upper groundwater in the sandy regions of the
Netherlands as a result of using fertilizers and manure in agriculture.
This program is a cooperative effort of the National Institute of Public
Health and Environmental Protection (RIVM) and Agricultural Economics
Research Institute (LEI-DLO). From march to august 1992 the upper
groundwater from 93 farms was sampled and analyzed for chloride, nitrate,
potassium, dissolved organic carbon and phosphate (ortho and total). The
report contains the monitoring results of the first year of the program.
Mean nitrate and potassium concentrations exceed quality objectives,
especially under grassland and silage maize on cattle farms. Nitrate and
potassium concentrations in the groundwater of arable farms were generally
lower than of cattle farms but on average above quality objectives. In the
reports to follow a more detailed analyses will be carried out and the
monitoring strategy will be evaluated with a view to the desirability of
detecting trends in groundwater quality in future.