Up to the 1980âs marginal soils were successfully ploughed for crop production, but
unfortunately those soils soon proved to be marginal. Due to high input costs, the
Department of Agriculture soon implemented the âsoil conversion schemeâ to promote the
conversion of those ploughed marginal soils to permanent pastures. It was especially the low
maize prices that triggered the conversion scheme in the 1980âs. Regardless the
implementation of the soil conversion scheme, many farmers unfortunately just abandoned
some of these marginal fields which resulted in many hectares of unproductive previously
cultivated fields, being referred to as abandoned fields. The aim of this study was to
investigate a few abandoned fields at a single location in the semi-arid central Free State in
an attempt to gather information on the dynamics of such disturbed ecosystems and identify
their restoration potential.
The study investigated the interaction between plant and soil variables to quantify the impact
of different soil physical and chemical characteristics on vegetation dynamics (species
composition and density). The species richness, as well as the influence of different soil
characteristics were determined to identify which might have the biggest influence on the
recovery potential of the disturbed area. The soil seed bank was also investigated to quantify
the survival potential of climax grass species on abandoned fields, and why these species do
not establish voluntarily on these disturbed areas. The main aim of the study was to quantify
the influence of soil characteristics on the vegetation dynamics of abandoned fields.
The results clearly showed that marginal soils, withdrawn from cash-crop cultivation, are
among the most seriously degraded areas with low soil fertility (N and C content). It is
creating a more favourable habitat for pioneer grass species. This study sheds more light on
the poor natural rehabilitation rate of abandoned fields in the semi-arid Free State Province
of South Africa. It was proven that the establishment of climax vegetation might be largely
influenced by phosphorus (P), cation exchange capacity (CEC), nitrogen (N), carbon (C), soil
compaction and the composition of the soil seed bank.
It was note worthy that some of the abandoned fields still showed very slow progress in
natural restoration after 20 years. The areas that showed least recovery needed to be
cultivated and established with a cultivated pasture like Digitaria eriantha sub. eriantha. On
the other hand, other areas recovered to such an extent that oversowing or the placement of
Themeda triandra sheafs might improve restoration. The best recovered areas can only be
upgraded in productivity by scientific management strategies which include long resting
periods. Drastic human interference is an absolute necessity to speed up the process of plant
succession (rehabilitation). Future investigation might include long-term trials to monitor the
reaction of vegetation and soil characteristics to the introduction of organic matter as well as
the seed of climax grass species.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-07172013-161331 |
| Date | 17 July 2013 |
| Creators | Myburgh, Tjaart |
| Contributors | Prof HA Snyman, Mr PJ Malan |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-07172013-161331/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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