Investigation of processes leading to nitrate enrichment in soils in the Kalahari Region, Botswana

authored by
M. Schwiede, W. H.M. Duijnisveld, J. Böttcher
Abstract

In Southern Africa elevated nitrate concentrations are observed in mostly uninhabited semi-arid areas. In the Kalahari of Botswana groundwater locally exhibits concentrations up to 600 mg/l. It is assumed, that nitrate found in the groundwater originates mainly from nitrogen input and transformations in the soils. Our investigations in the Kalahari between Serowe and Orapa show that cattle raising is an important source for enhanced nitrate concentrations in the soils (Arenosols). But also in termite mounds very high nitrate stocks were found, and under natural vegetation (acacia trees and shrubs) nitrate concentrations were mostly unexpectedly high. This nitrate enrichment in the soils poses a serious threat to the groundwater quality. However, calculated soil water age distributions in the unsaturated zone clearly show that today's nitrate pollution of the groundwater below the investigation area could originate from natural sources, but cannot be caused by the current land use for cattle raising.

Organisation(s)
Institute of Soil Science
Section Soil Biophysics
External Organisation(s)
Federal Institute for Geosciences and Natural Resources (BGR)
Type
Article
Journal
Physics and chemistry of the earth
Volume
30
Pages
712-716
No. of pages
5
ISSN
1474-7065
Publication date
2005
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Geophysics, Geochemistry and Petrology
Sustainable Development Goals
SDG 15 - Life on Land
Electronic version(s)
https://doi.org/10.1016/j.pce.2005.08.012 (Access: Unknown)