A comparative study of soil degradation between rangelands under communal grazing and controlled grazing in Alice, Eastern Cape

Duma, Monde Felix (2000) A comparative study of soil degradation between rangelands under communal grazing and controlled grazing in Alice, Eastern Cape. Masters thesis, Rhodes University.




A comparison of soil degradation between communal grazing and controlled grazing was undertaken in the Victoria-East district of the Eastern Cape. The study was undertaken in the communal rangeland of Dyamala village and the University of Fort Hare Research Farm to represent communal grazing and commercial farming management system respectively. The study used variables such as soil properties, soil loss, and vegetation cover to investigate soil degradation between the two rangelands which are under different management systems. Statistical tests (ANOVA) were used to determine the significance of differences between the two rangelands. A number of soil physical properties were used to quantify the state of degradation of each of the rangelands. This included particle size distribution of the soil, soil moisture, bulk density and porosity, aggregate stability, surface compaction and infiltration rates. The bulk density, porosity, aggregate stability and infiltration rates did not show any significant differences between the sites. These soil properties indicated a similar state of the soil between the two rangelands. However a significant difference in soil moisture and surface compaction was found between sites. The Research Farm had higher soil moisture and was less compacted than the communal rangeland. The two sites were more or less equally losing the finer soil particles through erosion. The erosion process selected the finer particles. In terms of two chemical soil properties, pH and soil organic matter, the two rangelands were similar as there were no significant differences between them. However the two rangelands were losing twice as much soil organic matter in the eroded sediment compared to the in situ soil. This was due to the loss of the finer soil particles through the erosion process. The two rangelands were thus degrading at a similar rate in terms of losing soil fertility. Sediment movement on the slope was monitored for eighteen storms using Gerlach troughs. In the short term the two rangelands seemed to be degrading at the same rate as there were insignificant differences during storm events. Cumulative sediment losses, however, were significantly different between sites as well as slope position. The Research Farm had lower soil movement (loss) than the communal sites. The erosion response of the Research Farm was 60 per cent of that of the communal rangeland indicating higher erosion in the communal area. Contrary to these results the soil depth of the A horizon did not reveal any significant differences between the sites but only between the different topographical positions of the slope. Moles and earthworms were found to be significant contributors of sediment in the erosion process in the communal system and the Research Farm respectively. Significant differences in vegetative cover were found between the sites, with the Research Farm having higher vegetation cover than the communal sites. The vegetation cover was however good in all three sites, being well above 80 per cent. The higher biomass of the Research Farm did not translate into effective vegetative cover. The vegetation in all sites was effective in arresting soil movement as witnessed by the amounts of sediment collected. Both rangelands were found to be in good condition, though the Research Farm was less degraded compared to the communal rangeland.

Item Type:Thesis (Masters)
Uncontrolled Keywords:Soil erosion, South Africa, Eastern Cape, Grazing
Subjects:G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions:Faculty > Faculty of Science > Geography
ID Code:2224
Deposited By: Ms Chantel Clack
Deposited On:23 Nov 2011 08:18
Last Modified:06 Jan 2012 16:22
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