Abstract
Fertilization of agricultural land in groundwater infiltration areas
often causes deterioration of groundwater quality. In addition to
nitrogen and phosphorous, potassium deserves attention. The fate of
potassium in the subsurface is controlled mainly by cation-exchange. Use
of the Potassium Adsorption Ratio (PAR), analogous to the Sodium
Adsorption Ratio (SAR) allows one to distinguish between leaching of
agricultural potassium to groundwater and desorption of potassium due to
increased hardness associated with increased manure spreading on a
calcareous soil. Two regional field studies in The Netherlands indicate
that groundwater below infiltration areas with agricultural land use,
has increased PAR values compared to pristine groundwater in seepage
areas and groundwater below infiltration areas with forest. Downward
transport of agricultural potassium is retarded compared to conservative
chloride due to cation-exchange. In one field study silicate weathering
is found to be a potential source for K in pristine groundwater when the
residence time is long and easily weatherable silicates, such as
glauconite, are present.
| Original language | English |
|---|---|
| Pages (from-to) | 244-254 |
| Journal | Journal of Hydrology |
| Volume | 254 |
| Issue number | 1 |
| Publication status | Published - 2001 |
