Lau Ka Wah Joyce. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 177-192). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of Contents --- p.vi / List of Tables --- p.xi / List of Figures --- p.xiv / List of Plates --- p.xvi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Environment of Hong Kong --- p.1 / Chapter 1.1.1.1 --- Topography --- p.1 / Chapter 1.1.1.2 --- Climate --- p.1 / Chapter 1.1.1.3 --- Expanding population --- p.3 / Chapter 1.1.2 --- Landslide history in Hong Kong and government action --- p.4 / Chapter 1.1.3 --- Slopes in Hong Kong --- p.6 / Chapter 1.1.4 --- Stabilization means --- p.7 / Chapter 1.2 --- Biotechnical stabilization --- p.8 / Chapter 1.2.1 --- Concept --- p.8 / Chapter 1.2.2 --- History --- p.9 / Chapter 1.2.3 --- Advantages and strengths of vegetation --- p.9 / Chapter 1.2.4 --- Other components in biotechnical stabilization --- p.11 / Chapter 1.3 --- The situation in Hong Kong --- p.12 / Chapter 1.3.1 --- Government policy on control of visual impact of slopes --- p.12 / Chapter 1.3.2 --- Landslip Preventive Measures (LPM) Program --- p.15 / Chapter 1.3.3 --- Slope landscaping proprietary systems --- p.16 / Chapter 1.3.3.1 --- Proprietary systems --- p.16 / Chapter 1.3.3.2 --- Problems and limitations --- p.20 / Chapter 1.4 --- Ecosystem reconstruction on slopes --- p.23 / Chapter 1.4.1 --- Concept --- p.23 / Chapter 1.4.2 --- Plant requirements --- p.24 / Chapter 1.4.3 --- Potential challenges --- p.24 / Chapter 1.4.3.1 --- Steep gradient and related problems --- p.24 / Chapter 1.4.3.2 --- Thin soil --- p.24 / Chapter 1.4.3.3 --- Water supply --- p.26 / Chapter 1.4.3.4 --- Nutrient availability --- p.27 / Chapter 1.5 --- Species selection --- p.28 / Chapter 1.5.1 --- Vegetation types --- p.28 / Chapter 1.5.2 --- Natives or exotics --- p.29 / Chapter 1.5.3 --- Currently employed species and problems --- p.29 / Chapter 1.6 --- The current study --- p.31 / Chapter 1.6.1 --- Objectives --- p.31 / Chapter 1.6.2 --- Significance --- p.31 / Chapter Chapter 2 --- Soil status and vegetation of cutslopes --- p.35 / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials and methods --- p.42 / Chapter 2.2.1 --- Physical properties of substrates on slopes --- p.43 / Chapter 2.2.1.1 --- Gradient --- p.43 / Chapter 2.2.1.2 --- Aspect --- p.43 / Chapter 2.2.1.3 --- Soil depth --- p.44 / Chapter 2.2.1.4 --- Bulk density --- p.44 / Chapter 2.2.1.5 --- Soil texture --- p.44 / Chapter 2.2.2 --- Chemical properties of substrates on slopes --- p.45 / Chapter 2.2.2.1 --- pH --- p.45 / Chapter 2.2.2.2 --- Conductivity --- p.45 / Chapter 2.2.2.3 --- Organic carbon --- p.46 / Chapter 2.2.2.4 --- Carbon: nitrogen ratio --- p.46 / Chapter 2.2.2.5 --- Total Kjeldahl Nitrogen --- p.46 / Chapter 2.2.2.6 --- Mineral nitrogen (Ammonium and nitrate) --- p.46 / Chapter 2.2.2.7 --- Total phosphorus --- p.47 / Chapter 2.2.2.8 --- Available phosphorus --- p.47 / Chapter 2.2.2.9 --- Major extractable cations --- p.47 / Chapter 2.2.3 --- Statistical analysis --- p.47 / Chapter 2.2.4 --- Other properties on slopes --- p.48 / Chapter 2.2.4.1 --- Green coverage --- p.48 / Chapter 2.2.4.2 --- Invaded species --- p.48 / Chapter 2.3 --- Results --- p.48 / Chapter 2.3.1 --- Physical properties of substrates on slopes --- p.48 / Chapter 2.3.2 --- Chemical properties of substrates on slopes --- p.51 / Chapter 2.3.3 --- Other properties of the slopes --- p.58 / Chapter 2.3.3.1 --- Green coverage --- p.58 / Chapter 2.3.3.2 --- Invaded species --- p.60 / Chapter 2.4 --- Discussion --- p.61 / Chapter 2.4.1 --- The physical properties of substrates on slopes --- p.63 / Chapter 2.4.2 --- Chemical properties of substrates and their seasonal changes on slopes --- p.66 / Chapter 2.4.3 --- Green coverage and its seasonal changes --- p.70 / Chapter 2.4.4 --- Comparison between the standards and results --- p.75 / Chapter 2.4.5 --- Other problems --- p.78 / Chapter 2.5 --- Summary --- p.79 / Chapter Chapter 3 --- Species selection for cutslope revegetation --- p.81 / Chapter 3.1 --- Introduction --- p.81 / Chapter 3.1.1 --- The need to expand species variety for revegetation --- p.81 / Chapter 3.1.2 --- Criteria for plant selection --- p.81 / Chapter 3.1.3 --- Advantages of grasses and herbaceous legumes --- p.83 / Chapter 3.1.4 --- Pot experiment --- p.85 / Chapter 3.2 --- Materials and methods --- p.86 / Chapter 3.2.1 --- Summer grasses --- p.88 / Chapter 3.2.1.1 --- Germination rate --- p.88 / Chapter 3.2.1.2 --- Pot experiment --- p.88 / Chapter 3.2.2 --- Summer legumes --- p.90 / Chapter 3.2.3 --- Winter grasses --- p.90 / Chapter 3.2.4 --- Winter legumes --- p.90 / Chapter 3.3 --- Results --- p.91 / Chapter 3.3.1 --- Soil properties --- p.91 / Chapter 3.3.2 --- Aboveground biomass production --- p.91 / Chapter 3.3.2.1 --- Summer grasses --- p.91 / Chapter 3.3.2.2 --- Summer legumes --- p.98 / Chapter 3.3.2.3 --- Winter grasses --- p.101 / Chapter 3.3.2.4 --- Winter legumes --- p.106 / Chapter 3.3.3 --- Foliar nutrient concentration --- p.111 / Chapter 3.3.3.1 --- Summer grass --- p.111 / Chapter 3.3.3.2 --- Summer legumes --- p.113 / Chapter 3.3.3.3 --- Winter grasses --- p.114 / Chapter 3.3.3.4 --- Winter legumes --- p.115 / Chapter 3.4 --- Discussion --- p.116 / Chapter 3.4.1 --- Aboveground biomass production --- p.119 / Chapter 3.4.1.1 --- Summer grasses --- p.119 / Chapter 3.4.1.2 --- Summer legumes --- p.121 / Chapter 3.4.1.3 --- Winter grasses --- p.122 / Chapter 3.4.1.4 --- Winter legumes --- p.125 / Chapter 3.4.2 --- Foliar nutrient concentration --- p.126 / Chapter 3.4.3 --- Common nutrient application and the plant requirements --- p.128 / Chapter 3.5 --- Summary --- p.129 / Chapter Chapter 4 --- Growth of summer grasses in a combination of stresses --- p.131 / Chapter 4.1 --- Introduction --- p.131 / Chapter 4.2 --- Materials and methods --- p.131 / Chapter 4.2.1 --- Study species --- p.131 / Chapter 4.2.2 --- Pot experiment --- p.132 / Chapter 4.3 --- Results --- p.132 / Chapter 4.3.1 --- Pot experiment --- p.132 / Chapter 4.3.1.1 --- Aboveground biomass --- p.132 / Chapter 4.3.1.2 --- Foliar nutrient concentration --- p.138 / Chapter 4.4 --- Discussion --- p.140 / Chapter 4.4.1 --- Pot experiment --- p.140 / Chapter 4.4.1.1 --- Aboveground biomass --- p.140 / Chapter 4.4.1.2 --- Foliar nutrient concentration --- p.141 / Chapter 4.5 --- Summary --- p.141 / Chapter Chapter 5 --- Growth of summer grasses on simulated slopes --- p.143 / Chapter 5.1 --- Introduction --- p.143 / Chapter 5.2 --- Materials and methods --- p.145 / Chapter 5.2.1 --- Study species --- p.145 / Chapter 5.2.2 --- Artificial panel trial --- p.145 / Chapter 5.2.2.1 --- Experimental setup --- p.145 / Chapter 5.2.2.2 --- Growth pattern and green coverage --- p.147 / Chapter 5.2.2.3 --- Sediment runoff and change in soil thickness --- p.147 / Chapter 5.3 --- Results --- p.148 / Chapter 5.3.1 --- Grass growth on artificial panels --- p.148 / Chapter 5.3.1.1 --- Aboveground biomass and green coverage --- p.148 / Chapter 5.3.2 --- "Relationship between rainfall, runoff and soil loss" --- p.149 / Chapter 5.3.2.1 --- Effect of rainfall on runoff --- p.149 / Chapter 5.3.2.2 --- Effect of runoff on soil loss --- p.151 / Chapter 5.3.2.3 --- Effect of rainfall on soil loss --- p.152 / Chapter 5.3.2.4 --- Effect of aspect --- p.154 / Chapter 5.3.2.5 --- Effect of green coverage on soil loss --- p.154 / Chapter 5.3.3 --- Percentage of greening --- p.155 / Chapter 5.3.4 --- Soil thickness --- p.157 / Chapter 5.4 --- Discussion --- p.159 / Chapter 5.4.1 --- Grass growth on artificial panels --- p.159 / Chapter 5.4.2 --- "Relationship between rainfall, runoff and soil loss" --- p.160 / Chapter 5.4.2.1 --- Effect of rainfall on runoff --- p.160 / Chapter 5.4.2.2 --- Effect of runoff on soil loss --- p.160 / Chapter 5.4.2.3 --- Effect of rainfall on soil loss --- p.161 / Chapter 5.4.2.4 --- Effect of aspect on runoff and soil loss --- p.163 / Chapter 5.4.2.5 --- Effect of green coverage on runoff and soil loss --- p.164 / Chapter 5.4.3 --- Effects of other variables --- p.165 / Chapter 5.4.3.1 --- Effect of green coverage --- p.165 / Chapter 5.4.3.2 --- Effect of aspect --- p.167 / Chapter 5.4.4 --- Soil thickness --- p.168 / Chapter 5.5 --- Summary --- p.168 / Chapter Chapter 6 --- Conclusion --- p.170 / Chapter 6.1 --- Summary of major finding --- p.170 / Chapter 6.2 --- Implications of the study --- p.172 / Chapter 6.2.1 --- Growth medium --- p.172 / Chapter 6.2.2 --- Species selection --- p.174 / Chapter 6.3 --- Limitations of the study --- p.175 / Chapter 6.4 --- Suggestions for further investigation --- p.175 / References --- p.177

The dynamics and complexities of climate-soil-vegetation relations in the Kruger National Park are poorly known. Although primary production and composition of the grass layer are very important components of the Park's ecosystem, equally little is known about the determinants of these parameters. A better understanding of these processes and relations will be of value to the management of this Park, as well as providing a better insight into these complex dynamics. A study was consequently undertaken covering a 14-year period to identify the most important determinants of above-ground grass production and composition. At the core of the study is the soil water balance. The use of evapotranspiration data in a study of this nature is however not absolutely essential, provided a variety of rainfall parameters are used, though it has the important advantage of providing a much more detailed and more complete insight into the relations of the grass sward with its environment. Stepwise and tree regression procedures were used to identify the important factors. It is concluded that rainfall in its various forms is the primary determinant of grass production, standing crop, and composition, the latter either as perennials or Decreasers. Secondary determinants, in varying degrees of importance, are the thickness and base status of the A horizon, distance to permanent drinking water, and competition by woody plants. Herbivore utilization is insignificant or at most, plays a relatively minor role. Herbivores appear to exert a negative influence on Decreaser abundance only when soil moisture stress exceeds a threshold level. When this is exceeded, relatively low herbivore densities are apparently sufficient to reduce Decreaser abundance. The definitions of Decreasers and Increasers consequently require revision to take into account the overriding influence of environmental factors, particularly those of soil moisture stress. The calibration of the disc pasture meter was re-evaluated. The relation between mean disc height and standing crop is non-linear. Up to a mean disc pasture meter height of 260 mm, the correlation between this parameter and above-ground standing crop is very strong (r2 = 0.95; P<0.0005). Beyond this height, the correlation is very poor (r2 =0.09; P<0.0005), apparently being strongly influenced by the structure of the grass plant, with tall grasses, or grasses with highly lignified culms resulting in a weaker correlation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

As restoration ecology has matured as a science there has been increased interest in the relationship between species diversity and landscape health. Degraded landscapes tend to be resource poor, which limits species diversity as only species which are capable of growing and reproducing in these resource limiting environments can inhabit the area. Additionally, the established species are strong competitors for resources and will exclude, by way of inter-specific competition, weaker competitor species attempting to invade the degraded area. Several studies have demonstrated that with increased species diversity the overall productivity and functionality of the grassland increases. Seedling development and competitive interactions between grass seedlings has a significant impact on the final community structure and species diversity. It is for this reason that aspects of the ecology of grass seedlings were investigated. The growth and competitiveness of Chloris gayana, Cynodon dactylon, Digitaria eriantha, Eragrostis curvula and E. tef seedlings were determined under three environmental stimuli, namely nitrogen availability, light availability and exposure to plant-derived smoke (in the form of smoke-infused water). The primary conclusion from the competition experiments was that the species can be split into superior and inferior competitors at the seedling stage. Chloris gayana, E. curvula and E. tef were the most competitive seedlings as they had the largest negative effect on the growth of other species (high nitrogen Relative Interactive Index (RII) = -0.449, -0.203 and -0.379 respectively) and they were least affected by competition (high nitrogen RII = -0.251, -0.168 and -0.248 respectively). The calculated RII indicates the strength of the competitive interactions, the more negative the RII the stronger the competitive interaction. Nutrient availability had limited effect on the competitive hierarchy of the tested species. Chloris gayana seedlings, however, increased in competitiveness with an increase in available nutrients. In other words, there was a decreased negative response to competition in a high nutrient environment (high nitrogen RII -0.251, no nitrogen RII -0.605). When D. eriantha was grown under varying shade, nutrient and competition levels it was evident that the primary stress factor was light deficiency (p<0.001), and nutrient availability had no affect on seedling growth (p=0.069). Smoke-infused water had no consistent affect on the germination success or the seedling’s root and shoot vigour for the five grasses. These results indicate that the introduction of a “2-phase” or “multi-phase” restoration plan may be beneficial for the development of species diverse rehabilitated grasslands. Manipulating the time and space that the different species are planted, or the distribution of nutrient concentration over the area, may increase the survivorship of all the species that are introduced to a restoration site. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.

Please read the section 05chapter5 (General summary and conclusions, especially p168-170) of this document / Thesis (DSc (Agriculture))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

Call number: LD2668 .T4 1963 H32 / Master of Science

Call number: LD2668 .T4 1979 N87 / Master of Science

Master of Science / Department of Agronomy / Scott A. Staggenborg / Volatile energy prices, energy independency, and environmental concerns have increased the demand for renewable fuel production in the United States. The current renewable fuel industry in the United States has developed around the conversion of starch into ethanol fuel, supplied mainly by corn (Zea mays L.) grain. Future energy demands cannot be met by corn grain alone; therefore greater amounts of biomass from traditional and alternative crops must be utilized. Nutrient removal by selected biofuel crops is important in order to determine biomass quality, required fertilizer inputs, and economic viability of biofuel cropping systems. The objectives of this study were to evaluate grain, stover, total biomass, and estimated ethanol yields of annual and perennial C4 crops grown under the same soil and weather conditions; and fermentable carbohydrate (FC) yields from extracted sweet sorghum juice. In addition, nitrogen (N), phosphorus (P) and potassium (K) concentrations of biomass were evaluated to determine total nutrient removal for annual and perennial crops. Field trials, at two locations in northeast Kansas, included corn, sorghum [Sorghum bicolor (L.) Moench] and perennial warm-season grass cultivars. Yields and nutrient removal were greater for annual crops than perennial grasses. Annual crop yields varied among cultivars, but were similar between locations and years. Perennial grass yields improved significantly from the 2007 establishment year to 2008, however nutrient removal was not affected by the yield increase. The highest grain yield and grain nutrient removal amounts were observed for corn across both years and locations. Total biomass yields were greatest for sweet and photoperiod sensitive sorghum cultivars. Average extracted sweet sorghum FC yields were 4.8 Mg ha[superscript]1. Estimated ethanol yields of sweet sorghum were greater than all other crop cultivars. Overall, nutrient removal was most affected by biomass yield variation among crop cultivars; however P concentrations, and subsequent removal, were dependent upon soil P levels at individual locations. These results suggest that annual crops can achieve the greatest biomass yields for multiple renewable fuel conversion processes, but are associated with high nutrient removal levels which must be considered when evaluating biofuel energy cropping systems.

Thesis (PhD (Agronomy))--University of Stellenbosch, 2006. / Vegetation dynamics and restoration strategies of degraded rangeland were investigated near a watering point in the Allaidege communal grazing area in Administrative Zone 3 of the Afar Region in the northeastern lowlands of Ethiopia. The degradation gradient formed by grazing pressure in the study area was stratified into four different areas based on the vegetation cover; severely degraded (SD), moderately to severely degraded (MSD), moderately degraded (MD) and lightly degraded (LD) areas. The study was initiated at the start of the rainy season in June 2003 and lasted untill December 2004. The objectives were to study the effects of the grazing pressure on plant species composition; on plant biomass production and basal cover; on rangeland forage quality; on the rangeland soil status and to determine and quantify viable restoration strategies for forage species in severely degraded rangelands. The botanical composition of the different degradation areas was determined by making a 250 point wheel point method survey in each of four 30 m x 30 m quadrats in each degradation area using the nearest plant approach. The botanical composition of each degradation area was determined by measuring the frequency of occurrence of the different life forms (perennial grasses, annual grasses and forbs) of the species recorded in the field. Accordingly, a significant interaction was observed in both seasons between the different degradation areas and life forms considered. A high abundance of annual grasses was evident in SD and MSD areas in both seasons. In the MD and LD areas, a three-fold increase in frequency was recorded for perennial grasses compared to the MSD area in 2003. In 2004, the frequency of annual grasses, forbs and perennial grasses in the MD area was almost similar to that of the LD area. The abundance of perennial grasses in the MD and LD areas was two- and five-fold higher compared to perennial grasses in the MSD and SD areas respectively. Biomass production was recorded by cutting the vegetation in 1 m x 1 m quadrats in each grazing area at ground level. The dry matter content of subsamples was determined in order to calculate the dry matter production of the quadrat. The differences in dry matter yield recorded in the different degraded areas was not significant for the 2003 season, although an increasing trend in yield was observed from the SD to MD areas. Significant yield differences were however recorded when one outlier in the data was excluded from the analysis. The significant differences occurred between the MD and SD areas where the MD area produced 2.4 t ha-1 more dry matter than the SD area. Similarly, in 2004 no significant yield difference was observed between the degradation areas. However, the contribution of different species to dry matter yield varied in the different degradation areas. Setaria verticillata, Sporobolus ioclados and Paspalidium desertorum were found to be the major species contributing to the dry matter producion in the SD area, S. verticillata and P. desertorum in the MSD area, Chrysopogon plumulosus and P. desertorum in the MD area and C. plumulosus and Panicum coloratum in the LD area. The percentage basal cover was calculated from the number of basal strikes recorded at 1 000 points in each plot of each degradation area using the wheel point method. The total basal cover percentage did not significantly change along the degradation gradient in any of the seasons. However, data for both seasons showed an increasing trend of total basal cover percentage closer to the watering point compared to areas further away from the watering point, except for the SD area, which had the lowest basal cover percentage. The contribution to percentage basal cover by some species decreased while it increased for some other species in grazing areas near the watering point. Forage quality was investigated by analysing sub-samples of the forage samples taken to determine biomass production. The forage samples were analysed for neutral detergent fibre (NDF), acid detergent fibre (ADF), crude protein (CP), lignin, in vitro dry matter digestibility (IVDMD), phosphorus (P), and calcium (Ca) content. The forage showed a decrease in NDF and ADF content in areas close to the watering point in both seasons. This decrease in fibre content was accompanied by an increase in CP content close to the watering point. The increase in CP was significant for the SD area in both seasons. Although a similar trend was observed in both seasons, the CP content was found to be significantly higher in 2004 than in 2003. The results of the lignin analysis were inconclusive if the data of both seasons are considered. It does appear however as if the lignin content of the forage was generally higher in 2003. The 2 years pooled average of P content of the forages showed insignificant variation along the degradation gradient. However, an increase in P concentration of the forages was evident in areas far from the watering point. Contrary to this, Ca concentration was significantly higher in the SD area compared to areas further away from the watering point. Hand clipped forage samples and esophageal collected forage samples were analysed to compare the quality of the samples. Due to the fact that only two animals were available for esophageal collection, differences were in most cases not significant at the 5% level, but trends indicate that animals select higher quality forage than what is assumed based on hand clipping. Organic carbon (OC) content, total nitrogen (N) content, available phosphorus (P) content, available potassium (K) content, exchangeable calcium (Ca) and magnesium (Mg) contents, cation exchange capacity (CEC), total exchangeable bases (TEB), exchangeable sodium percentage (ESP), soil acidity (pH) and base saturation of soils in the different degradation areas were determined by means of acknowledged laboratory methods. No significant differences in OC, N, P, K, Ca, Mg and K content of soil in the different degradation areas could be observed. There was however an increasing trend for OC and N content with distance from the watering point. Sodium concentration and pH increased significantly in areas close to the watering point. Cation exchange capacity content of the soil was variable and no clear trend could be established. Significantly higher TEB and ESP contents were observed in the SD area. In general, the differences in plant biomass production and basal cover, botanical composition, forage quality and soil status over the degradation gradient clearly implicates the negative impact of unrestricted grazing pressure on the rangeland around the watering points. In the rangeland restoration trial, establishment of three local and three exotic grass species in the SD area was investigated. Treatments applied included application of inorganic fertilizer, dry dung organic manure and grass mulch. The mulch treatments caused a significant yield increase for all the sown species. Among all the species, Ischaemum afrum and Tragus berteronianus performed better and produced significantly higher dry matter yields than Enteropogon rupestris, Chloris gayana and Panicum coloratum. In general the study indicated the importance of mulching when planning to restore degraded rangeland under arid environmental conditions.

Thesis (PhD(Agric) (Agronomy))--University of Stellenbosch, 2007 / A selection of species suitable for cover crop management in the different wine grape regions is required to enable more producers to apply this environment friendly practice in a sustainable manner as part of an integrated production strategy. The correct management practice(s) to be applied to these species over both the short and long term in a cooler and warmer wine grape region needed clarification. The effect of seeding date on the dry matter production (DMP) and weed control efficacy of seven grasses and sixteen legumes, as well as varieties of three of these species, was determined during 1991 and 1992. The decomposition rate of the mulches was determined. In the cooler climate of Stellenbosch (33o55'S, 18o52'E), the Medicago species, subterranean clovers, pink Seradella and three Vicia species did not compete effectively with the winter weeds if the weekly precipitation from mid-March to mid-May (autumn) exceeded 18 mm. The two oat species, as well as rye and triticale produced more than five t/ha of dry matter if the precipitation exceeded 18 mm per week. The DMP of the above-mentioned species indicated that these species could be considered for cover crop management in Lutzville (31o35'S, 18o52'E), if full surface irrigation of 18 mm per week could be applied for 10 weeks directly after sowing, followed by 18 mm fortnightly. Seeding date had a significant effect on DMP in both regions. A highly significant correlation (r = 0.85, p ≤ 0.0001) existed between the decomposition rate of the mulches and the initial amount of dry matter present on the soil surface.