Browsing by Author "Everson, Theresa Mary."
Now showing 1 - 11 of 11
Results Per Page
Sort Options
Item Black wattle (Acacia mearnsii) and the fever tree (Acacia xanthophloea) in alleycropping systems.(2006) Nhamucho, Luis Jeremias.; Rijkenberg, Fredericus Hermanus Johannes.; Everson, Theresa Mary.; Underwood, Timothy Michael.; Matakala, Patrick.Alleycropping is an agroforestry technology of planting crops between rows of trees, preferable legumes to promote an interaction among them with positive benefits in terms of improving soil fertility and hence good crop yields. The technology has been tested with a variety of trees/shrubs species in association with crops (alleycropping) or with grasses (alleygrazing), sometimes with encouraging results and sometimes not, in a wide range of environmental conditions around the world. Research in alleycropping started in late 1970s and sinc~ then many publications have been released. However, little or nothing has been reported about this technology using black wattle and the fever tree, two nitrogen-fixing trees common in South Africa and reported as fast-growing species which produce a considerable amount of biomass within a short period of time. Due to that fact, a two-year trial was established in 2003 at the Ukulinga research farm, Pietermaritzburg, South Africa to evaluate the potential of the two tree species under alleycropping with maize and cowpeas as joint intercrops, under alleycropping with pumpkin, and under alleygrazing with Eragrostis curvula and with Panicum maximum. The trial assessed the crop yields and the biomass production from all the components, and their fodder digestibility using Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) determinations. Additionally the changes in tree grovlth vaa."'i.ables (difu~eter, total height, total \lollhl1e and biomass) were mortitored to produce regression equations to predict those variables, one from another, using regression analysis. The diameter was taken at ground level (dgl) and at the height of 1.3 m, normally called diameter at breast height (dbh). The results showed that tree growth and biomass production were better in black wattle alleycropping than in association with the fever tree. The average dgl of black wattle after 12 months was 48mm and the average dbh was 36mlll. Over the same period the total tree height was about 406cm. A tree pruning was done to one-year old black wattle in the whole trial and the prunings produced about 5.6t/ha of fresh foliage biomass in the association with maize and cowpea and 4.5t/ha in the association with pumpkin. In alleygrazing the growth variables were similar to those obtained in alleycropping but the biomass production was considerably different. The prunings produced about 7.66t/ha of fresh foliage biomass. The dry matter biomass from the prunings was 1.96t/ha, 1.58t/ha and 2.68t/ha in the association with maize and cowpeas, pumpkin and E. curvula respectively. The dry matter was obtained from 4days- oven-dried samples and it was 35% of the fresh foliage biomass and 60% of the fresh woody biomass. The fever tree did not grow significantly during the study period and due to that fact, the species was discarded from the study. Similarly, because after several endeavours using different seed lots, P. maximum had germinated very unevenly, and this grass was excluded from the experimentation. Values ofNDF and ADF less than 35% are considered good, between 35% and 60% fair and poor if greater than 50%. Using is classification the NDF and ADF values from this study were good in pumpkin (30.5% and 29.9%) and cowpeas (36.5% and 46.9%) biomass, fair in E. curvula (41.9% and 39.9%) and maize stover (53.6% and 42.1%) and poor in black wattle (76.58% and 68.1%) foliage. If black wattle is to be used as fodder, it must be mixed with highly digestible fodder like P. maximum, Digitaria sp., and other legume plants, to increase animal intake and to avoid any risk of it becoming an animal hazard due to tannin effects. The regression equations produced linear relationships between dgl and age, and biomass and dbh. The other interactions were not linear. The best equations were obtained in the interaction between dgl and age (dgl= 4.8*Age -7.03; R2 =0.86; SE= 6.6), dgl and height (h= -0.03dg12 + 10.5dgl - 21.25; R2= 0.96, SE= 42.9, h= height), biomass and dbh (lny = 2.409*lndbh; R2=0.99, SE=O.O, Y= tree foliage biomass). During the study, monkeys, cattle, birds and bushbucks posed a threat to the success of the study due to damage they caused to the crops. It was possible to keep the damage below the critical levels, although at high cost.Item The effect of bioslurry, grass clippings and pumpkin live mulch on soil water content and maize production.(2016) Ngubo, Nelile.; Odindo, Alfred Oduor.; Everson, Theresa Mary.Abstract available in PDF file.Item Evaluation of improved Brachiaria grasses in low rainfall and aluminium toxicity prone areas of Rwanda.(2010) Mutimura, Mupenzi.; Everson, Theresa Mary.Abstract available in the print copy.Item Grazing management in the communal rangelands of the Upper Thukela, Kwazulu-Natal.(2005) Tau, Mahlodi Solly.; Everson, Theresa Mary.The grazing management project in the Okhombe ward of the Amazizi Tribal Authority formed part of the National Department of Agriculture's LandCare program to address communal natural resource management issues. Okhombe land is communal whereby every member of the community is the legal owner of the rangeland with individual ownership of stock with the chieftaincy playing a major role in land allocation. In order to avoid critics of the past and address the top-down approach of the past interventions, a participatory approach was conducted in the planning and implementation of the grazing system. The service providers held a series of visioning workshops with the community in an effort to better understand community resource use patterns, needs, constraints and opportunities as part of the participatory approach. Issues identified by the community were the need for fencing grazing camps, animal health improvement, subdivision of rangeland and crop fields and the development of a rotational grazing system. The main aims of this study were to develop a participatory grazing plan with the community, develop and support institutional structures governing range management, and build capacity of the community in range management. The effect of the current grazing system on species composition was determined. In addition to these, the project investigated the potential different fodder trees has on alleviating feed and nutritional deficit, particularly during the dry winter months of the Upper Thukela. Among the main achievements of this study was the development and strengthening of local institutional structures and effective liaison by all structures with the Inkosi and the tribal council. The community developed a rotational grazing plan, marked the camp boundaries, produced digital maps and successfully built fence boundaries (approximately 20 kms of fencing) to divide their land. The fence boundaries separated the crop fields and rangeland, closed ward boundaries in the upland to prevent access by cattle from neighbouring wards, and divided the land into three camps. Six crush pens were constructed in each subward of the Okhombe ward. A communal herders fund opened and fence construction improved crop yields due to a decrease in crop damage by cattle. Okhombe ward, located in the Highland Sourveld region of KwaZulu-Natal, experiences feed and nutrition deficits to ruminants during winter. The prevailing species composition in Okhombe was investigated as part of the grazing plan. The veld condition of the sites ranged from poor (40.7%) in the bottomland to an averaged of 47.0% in upland sites. The most distinctive feature of the rangeland in this area was the loss of highly palatable Decreaser grass species (P <0.05), such as Themeda triandra in the bottom slopes « 1300 m) when compared to the upland (> 1800 m). The proportional abundance of Decreaser species accounted for an averaged of 1.02% of the bottomland and an averaged of 11.5% of the upland compared to the values of 49% in the benchmark (grassland in optimal condition). The composition of the less palatable Increaser Il species was very high at all elevations (1200 m -80.7%, 1400 m - 75.8% and 1700 m - 55.7%) when compared to the low benchmark composition of 19%. The dominant grasses of the bottom slopes were Increaser Il species, such as Eragrostis curvula, Eragrostis plana and Sporobolus africanus and unpalatable Increaser III species such as Aristida junciformis. A significant difference (P < 0.05) in the composition of Decreaser, Increaser I and Increaser Il species was found between the bottom and slopes compared to the upland region. However, the grass cover formed by these tufted species was generally high, making it more resistant to physical degradation. The bottom slope ranged from reasonable to excellent cover (16.9%), the middle slope ranged from reasonable (15.9%) to a good cover of 18.1%, averaging 16.7% and a range of 16.1% to 17.9% for the upland plateau. In the agroforestry trial the potential of different fodder species for supplementing fodder was examined. Leucaena leucocephala had the potential of being a suitable fodder tree species for use in alley cropping (P < 0.05) compared to Morus alba and Acacia karroo. Results from the partially intercropped treatments showed that L. leucocephala yield (665 kg ha-I) varied significantly (P < 0.05) from the A. karroo (378 kg ha-I) and M alba yield (345 kg ha-I). Treatments that were fully intercropped varied, but no significant difference (P > 0.05) were recorded. Morus alba produced the least yield of 345 kg ha-I, A. karroo yielded 378 kg ha-1 and 1. leucocephala recorded the high of 664 kg ha-I. Results from the second season showed similar trend in that 1. leucocephala yielded a significant (P < 0.05) fodder production of 1715 kg ha-I in comparison to M. alba (1101 kg ha-I) and A karroo (1140 kg ha-I). M alba yielded the least dry matter production (P < 0.05) but had high potential (P < 0.05) for addressing lack of firewood in rural areas. Morus alba yielded high fuel wood production from both two seasons. There were no significant differences in fuel wood yield (P > 0.05) from the partially intercropped M alba (507.9 kg ha-I) and 1. leucocephala (455.0 kg ha-I) but the yield from both species varied significantly from the A. karroo yield (103.kg ha-I). With regard to fully intercropped plots, fuel wood yield from all tree species varied significantly, A karroo resulting in low yield (63 kg ha-I), 1. leucocephala recorded 243 kg ha-l and M alba the highest yield of 444 kg ha-I. In the second season, M. alba yielded an averaged fuel wood production of 728 kg ha-l and a low of 439 kg ha-I from 1. leucocephala. Acacia karroo, a slow growing indigenous tree, might be preferred by farmers due to its less branches resulting in minimal light competition with crops. Leucaena leucocephala tend to grow slowly in its initial establishment stage, but once roots become well established, it grows fast and produces high quantity of fodder. The effect all fodder trees had on crop yield was not negative during the trial period and further research on long term effects of alley cropping is recommended. The conclusions drawn here were based on tree growth and their likely impact in alley cropping. Leucaena leucocephala was also recommended as a preferred species for rural ruminants based on the forage quality study. The results showed high content of crude protein (19.27%), low NDF content (50.38%) and very low tannin content (1.19%) from 1. leucocephala compared to A. karroo with a high tannin content of 5.69%. Acacia karroo had a crude protein content of 13.60%, NDF percentages of 44.16 and 34.64% of ADF content. Morus alba also had a recommended chemical composition of 11.71% of CP, 42.86% of NDF, 36.96% of ADF and a low tannin content of 0.65%. L. leucocephala foliage proven is readily degradable under different diet ranging within 24 hrs of intake (P < 0.001) compared to other feeds. L. leucocephala had high dry matter loss degraded from the rumen under Eragrostis hay diet with poor nutrients to high protein concentrates diet. Under the Eragrostis hay diet for instance, L. leucocephala tend to degrade rapidly with values of dry matter loss ranging from 32.2% to 39% at 4 hrs to 16 hrs, when compared to low dry mater loss of 26% at 4 hrs to 31.33% at 16 hrs. Feeds such as M alba tend to degrade slowly within 24 hrs of intake and rapidly degrades after the stated period. The ep content of maize stover was very low ranging from 1.60% in maize stalks to 2.63% in maize leaves. The fibre content in maize stover was very high when compared to lower values in fodder samples. The NDF content ranged from 77.92% in maize leaves to 81.60% in maize stalks. Maize leaves when compared to a combination of maize leaves and maize stalks sole tend to degrade better within 24 hrs of intake. This was due to low (P < 0.05) degradability rate of maize stalks compared to a combination of maize stalks and leave and leaves sole and least NDF content in maize leaves might have attributed to these results. Due to poor chemical compositions of these roughage samples, the study recommended the establishment of fodder banks and agroforestry systems to curb the nutrients deficit during winter. In conclusion therefore, this study highlight that the sustainability of rural systems to manage communal grazing land should be further explored. Most of the challenging issues in communal range management are social in nature rather than technical concepts. These include ways of improving social contributions from cattle to the community while maintaining cultural values of the use of cattle. The interventions in communal range management by service providers should understand the institutional arrangements within a community and an attempt to strengthen such existing structures is recommended. Further interventions by service providers in Okhombe ward should bring in the planning discussions, experts from social sciences, to deal with understanding of community dynamics. Complexities in communal range management involve dealing with non-stock owners within project boundaries. Communities from neighbouring wards should not be ignored and ways of improving communications and updating project details to them should be formulated. Shortage of land and closing of ward boundaries to prevent access to land by neighbouring wards is among community complexities to be explored. Communities in rural lands do share land and in most cases boundaries are known but invisible by an outsider to identify. It is important to strengthen and maintain every success in communal lands as that may form core of the project. Successes on grazing management by locals is far from being the improvement in veld but there are rather various factors to the successes of grazing projects in rural areas. Examples of successes based on Okhombe project are reduction in stock theft, improved in relationship between community and locals institutions, a reduction in stock mortalities during winter and improved animal health. Veld improvement is among successes but there are accomplishments phases to fulfil before focusing on improvement of species composition.Item The impact of communal land-use on the biodiversity of a conserved grassland at Cathedral Peak, uKhahlamba-Drakensberg Park, South Africa : implications for sustainable utilization of montane grasslands.(2004) Peden, Moraig Isobel.; Hamer, Michelle Luane.; Everson, Theresa Mary.South African grasslands are under-conserved and there is a need to expand conservation efforts beyond the boundaries of protected areas. While communal grasslands have conservation potential they are generally over-utilized and the impact of communal land-use on biodiversity is poorly studied. At the same time there is pressure on protected areas to allow for the sustainable utilization of biodiversity. The aim of this study was to examine the impact of communal land-use on various components of biodiversity and to make recommendations regarding communal use of protected areas. A fence-line study was conducted to assess the impact of eight years of controlled communal land-use on biodiversity in the uKhahlamba-Drakensberg Park. The communally used land (referred to as the lease land) which was used for controlled grazing as well as plant collection was compared with land under formal conservation. Vegetation was sampled using the importance score method and veld condition assessments. Selected invertebrate taxa were sampled using sweep netting, colour pan traps and transects and were identified to morphospecies level. Multivariate statistics revealed that sites generally grouped according to landscape position rather than land-use. No significant differences were found in diversity, evenness, richness or veld condition between the lease and conservation land. However, more than twenty-five percent of vegetation and invertebrate species were found exclusively in the lease or conservation land, suggesting that different suites of species were supported by the two landuses. Four alien plant species were found exclusively in the lease land, while one vulnerable and one rare plant species were found only in the conservation land. Further research is required to assess whether biodiversity was diminished by controlled communal. While the lease concept may offer potential as a low-use buffer zone, localised damage from cattle paths and weak enforcement of grazing agreements were areas of concern. Keywords: communal grass)ands, grassland flora, grassland invertebrates, transfrontier park.Item Keeping cattle in a changing rural landscape : communal rangeland management in Okhombe, KwaZulu-Natal, South Africa.(2011) Salomon, Monique Louise.; Fincham, Robert John.; Everson, Theresa Mary.; Allsopp, Nicky.A research journey involving people, cattle, and the landscape in rural Okhombe in the western part of the province of KwaZulu-Natal and lying at the foot of the uKhahlamba Drakensberg Mountain Range, South Africa, is the focus of this work. Using action research involving community members as co-researchers, it investigates why a rotational resting system for communal cattle grazing collapsed within six months of its launch. Despite having been designed in a participatory manner, the rotational resting system was not applied by cattle keepers. As a backdrop to the concern around the rotational resting system, it is necessary to understand how the current landscape of Okhombe was shaped. The history of the uKhahlamba Drakensberg Region over the past two hundred years was, therefore, explored. Four historical episodes were distinguished: economic expansion, nature conservation efforts, colonial and apartheid legislation, and encounters between people all left their imprint on the landscape. Digitized maps of aerial photographs of Okhombe, taken between 1945 and 2004, showed how Government intervention changed people’s multifunctional use of the landscape to concentrated settlements and cropping fields in the valley and cattle grazing on the mountain slopes. A survey in Enhlanokhombe, one of the sub-wards of Okhombe, further investigates how cattle keepers use the rangeland commons, and what determines these practices. People are keeping fewer cattle than in the past. A 24% decrease in cattle numbers was recorded between 2001 and 2008. Cattle keepers perceive stock theft as the most important threat. Yet, figures of stock losses showed that cattle disease resulting in death is an equally pressing problem. The decline in authority of traditional leaders and the view that herding is a family task have compounded the dominant management practice of continuous grazing by cattle. Rotational resting was found to be unsuited to the majority of cattle keepers who want to keep a close watch on their herds as they graze on the lower hill slopes. People in Okhombe disagreed about the condition of the range and what comprised appropriate grazing management. A community initiative has emerged to form cattle patrols to address stock theft. If successful, it may further enhance collective action. The concern with communal grazing management investigated in this research and in the Okhombe Landcare project, of which it was part, aimed to reverse land degradation and overgrazing. An analysis of digitized maps of Okhombe taken in the period between 1945 and 2004, however, showed that soil erosion did not increase rapidly as is commonly assumed by conventional rangeland scientists and extension staff. Rather, an increase in bare soil coincided with a period of drought. The focus of the Okhombe Landcare project on combatting soil erosion and rehabilitate degraded lands was underpinned by a particular interest in and need to conserve the uKhahlamba Drakensberg as a near-pristine wilderness landscape which provides marketable ecosystem goods and services. As such, cattle keeping in Okhombe can be described as being embedded in a social-ecological system comprising a series of nested, self-organizing subsystems which are interconnected. Sub-systems include the cattle production system, cattle grazing management practices, the wider ecosystem, and government policies and regulations. A spatial-temporal and systemic approach is proposed to make meaningful, policy-related decisions regarding communal rangeland management in the future. Such an approach would enable cattle keepers, other rangeland users, and outside stakeholders, such as extension workers and policy makers, to respond effectively to changes in the landscape by taking into consideration and balancing a complex set of biophysical, socio-political, and economic variables.Item Rangeland degradation assessment using remote sensing and vegetation species.(2011) Manssour, Khalid Manssour Yousif.; Everson, Theresa Mary.; Mutanga, Onisimo.The degradation of rangeland grass is currently one of the most serious environmental problems in South Africa. Increaser and decreaser grass species have been used as indicators to evaluate rangeland condition. Therefore, classifying these species and monitoring their relative abundance is an important step for sustainable rangelands management. Traditional methods (e.g. wheel point technique) have been used in classifying increaser and decreaser species over small geographic areas. These methods are regarded as being costly and time-consuming, because grasslands usually cover large expanses that are situated in isolated and inaccessible areas. In this regard, remote sensing techniques offer a practical and economical means for quantifying rangeland degradation over large areas. Remote sensing is capable of providing rapid, relatively inexpensive, and near-real-time data that could be used for classifying and monitoring species. This study advocates the development of techniques based on remote sensing to classify four dominant increaser species associated with rangeland degradation namely: Hyparrhenia hirta, Eragrostis curvula, Sporobolus africanus and Aristida diffusa in Okhombe communal rangeland, KwaZulu-Natal, South Africa. To our knowledge, no attempt has yet been made to discriminate and characterize the landscape using these species as indicators of the different levels of rangeland degradation using remote sensing. The first part of the thesis reviewed the problem of rangeland degradation in South Africa, the use of remote sensing (multispectral and hyperspectral) and their challenges and opportunities in mapping rangeland degradation using different indicators. The concept of decreaser and increaser species and how it can be used to map rangeland degradation was discussed. The second part of this study focused on exploring the relationship between vegetation species (increaser and decreaser species) and different levels of rangeland degradation. Results showed that, there is significant relationship between the abundance and distribution of different vegetation species and rangeland condition. The third part of the study aimed to investigate the potential use of hyperspectral remote sensing in discriminating between four increaser species using the raw field spectroscopy data and discriminant analysis as a classifier. The results indicate that the spectroscopic approach used in this study has a strong potential to discriminate among increaser species. These positive results prompted the need to scale up the method to airborne remote sensing data characteristics for the purpose of possible mapping of rangeland species as indicators of degradation. We investigated whether canopy reflectance spectra resampled to AISA Eagle resolution and random forest as a classification algorithm could discriminate between four increaser species. Results showed that hyperspectral data assessed with the random forest algorithm has the potential to accurately discriminate species with best overall accuracy. Knowledge on reduced key wavelength regions and spectral band combinations for successful discrimination of increaser species was obtained. These wavelengths were evaluated using the new WorldView imagery containing unique and strategically positioned band settings. The study demonstrated the potential of WorldView-2 bands in classifying grass at species level with an overall accuracy of 82% which is only 5% less than an overall accuracy achieved by AISA Eagle hyperspectral data. Overall, the study has demonstrated the potential of remote sensing techniques to classify different increaser species representing levels of rangeland degradation. In this regard, we expect that the results of this study can be used to support up-to-date monitoring system for sustainable rangeland management.Item Re-vegetation dynamics of land cleared of Acacia mearnsii (black wattle)(2005) Glaum, Melanie Jane.; Zacharias, Peter John Kenneth.; Granger, James Edmund.; Everson, Theresa Mary.; Smith, M.The overall aim of the study was to investigate re-vegetation of disturbed sites, using nursery grown plugs (from seedling trays) of Themeda triandra, Heteropogon contortus and Hyparrhenia dregeana in order to reach practical management guidelines for re-vegetation using indigenous grass plugs. A number of field trials were set up at Kamberg Nature Reserve (29°24'S, 29°40'E) on a site that was clear felled of A. mearnsii in October 1997. The trials were established in January 1998 and January 1999. A total of approximately 52 ,000 nursery raised plugs of T. triandra, H. contortus and H. dregeana were planted into an area of approximately 7,000 m2 . In the planting density trial , plugs of H. dregeana only and a combination of T. triandra/H. contortus were planted at 15 cm and 30 cm spacings. The T. triandra/H. contortus combination at 30 spacing showed the greatest survival and lateral plant growth (tiller number and basal area) and this combination is thus recommended. In the over-sowing trials, the H. dregeana and T. triandra/H. contortus combination at both 15 cm and 30 cm spacing were over-sown with E. curvula. The survival and lateral growth of the T. triandra/ H. contortus combination at 30 cm was again greater than the other treatments. Over-sowing with E. curvula suppressed the survival and lateral growth of the planted plugs across all treatments compared to not over-sowing. The over-sown conditions showed a significant decrease in the diversity of the plots, both in the number of species present and the Shannon diversity index. An area that had been cleared of A. mearnsii and sown to E. curvula 25 years previously was shown to have a lower number of species than the neighbouring veld. Nursery raised plugs of T. triandra were planted into the mature E. curvula in an attempt to improve the biodiversity of these areas. To re-introduce T. triandra into these E. curvula swards the plugs must be planted into the centre of a gap rather than around the base of an E. curvula plant. For improved survival of the plugs the E. curvula tufts must be clipped, while for best lateral growth the E. curvula tufts must be sprayed with a glyphosate herbicide three months prior to planting and clipping. However, the added expense of spraying and clipping is not warranted as the clipped treatments also showed good growth. Transplant shock is common when planting nursery raised plugs out into the field, as there is a relatively small root volume in the plug compared to the above ground leaf biomass. Alleviation of moisture stress at planting using a starch based polymer with high water holding capacity (Terrasorb®) and a white, needle punched geo-fabric (Agrilen®) to provide a seven day period of artificial shade after planting did not show significant improvements over the control with regards to survival or plant growth. Thus these methods of moisture amelioration are not recommended in revegetation through planting of plugs at this study site. A trial was established to investigate the biomass production of six different treatments to determine their potential to support a fire. The total biomass for the plots which were over-sown by E. tef and planted to only H. dregeana were on average sufficient for a fire, but there was a discontinuous fuel load across these plots, especially in the replications that had very low survival rates and thus these plots could not be burnt. The control and herbicide sprayed plots also showed sufficient fuel load for a fire, but this fuel load was made up of A. mearnsii saplings and bramble with very little grass cover and thus a fire would not have burnt through these plots either. The T. triandra/H. contortus combination did not produce sufficient fuel load, due to poor survival. Thus only the plots over-sown with E. curvula were able to burn in this trial and as a burning trial per se the trial was abandoned. Seed bearing hay (thatch) was collected in early summer (December 1997) and late summer (April 1998). Both times of year of harvesting proved to be successful in terms of grass cover, although the early harvested thatch had a greater number of species per plot. The Shannon diversity indexes of the two treatments were not significantly different. The multi-response permutation procedure technique confirmed that there was a compositional difference between the treatments. By the end of the trial Harpochloa falx and T. triandra and H. dregeana were indicators for the early and the late harvested thatch respectively. Comparing the thatching trial and the planting density trial indicated that the T. triandra/H. contortus combination at 30 cm spacing would be recommended to maximize biodiversity. The summer months have been shown to be the best time to plant the plugs, although the actual success will be dependant on the conditions within a particular year. The plugs should not be kept in the nursery for longer than three months and larger plugs (96 seedlings per tray) should be used. Nursery raised plugs of T. triandra and H. contortus were planted in an equal mix in an area that was cleared of A. mearnsii in 1996. By June 1998 661 H. contortus seedlings and 14 T. triandra seedlings had germinated naturally. The November 1998 population consisted of 418 H. contortus seedlings and 18 T. triandra seedlings. By May 2000 the June 1998 population showed a survival of 78.4% and the November 1998 population showed a survival of 91 .1 %. In the various trials, the ability of the nursery raised plugs used for re-vegetation to suppress the regrowth of A. mearnsii was investigated by determining the number of A. mearnsii seedlings per metre squared. The plant spacing and species of plugs used did not have a significant effect on the number of A. mearnsii seedlings per metre squared. Over-sowing with E. curvula did, however, significantly suppress the wattle re-growth. In the thatching trial the early harvested plots showed lower numbers of A. mearnsii per metre squared than the late harvest plots, as they were covered with a thick layer of thatch soon after the A. mearnsii was cleared which suppressed the A. mearnsii re-growth. Although E. curvula is able to produce a high biomass and suppress the A. meansii seedlings, it has a detrimental effect on the biodiversity of the area. Therefore, in conservation areas, where biodiversity is of great importance the planted plugs (at 30 cm spacing) or seed bearing hay must be used in preference to sowing E. curvula , although it must be remembered that greater follow up control is likely to be needed with planted plugs or seed bearing hay. The area must be planted or thatched as soon as possible after clear felling to provide competition for the A. mearnsii seedlings.Item Seedling establishment of Themeda triandra Forssk. in the montane grasslands of Natal.(1994) Everson, Theresa Mary.; Yeaton, Richard I.Soil erosion and vegetation destruction have reached serious proportions in disturbed areas of the montane grasslands of the Natal Drakensberg. Little is known of the inherent ability of indigenous grasses to produce viable seed and establish seedlings for rehabilitation programmes. This study examined the effects of fire and small-scale disturbance on the seedling dynamics of the dominant grass, Themeda triandra Forssk. Annual seed production of T. triandra increased with length of burning rotation, ranging from 21 seeds m⁻² in the annual winter burn to 485 seeds m⁻² in the five-year burn. High predation of seeds (70-98%) and low viability (37% in 15 month-old seeds) contributed to the poor representation of T. triandra in the seed bank when compared to the aboveground vegetation. Seedling densities and survival were monitored by mapping quadrats at six-weekly intervals from November 1986 to September 1989. Highest establishment of T. triandra was recorded in the biennial spring burn treatment (< 184 seedlings m⁻²). Microclimatic studies of the seedling environment demonstrated that increases in photosynthetically active radiation following burning, and high soil moisture associated with accumulation of litter, favour seedling establishment. The main constraint to seedling establishment was high mortality in winter which resulted in a 1% survival of seedlings of T. triandra during the three-year study. This indicates that in the fire-climax grasslands of the study, seedlings contribute little to the population structure. The most significant factor contributing to low survivorship is intraspecific competition between seedlings. Spacing of seedlings in rehabilitation programmes is therefore a critical factor in optimizing seedling establishment. Analysis of the fate of seeds of T. triandra between their production and establishment, showed that the main constraints for seedling establishment were predation, low viability and poor germination. A population model, based on transitions between seeds, seedlings and mature tufts, predicts that a biennial spring burn is the optimal treatment for maximising both seedling establishment and vegetative growth.Item The use of bioslurry for fodder production in sustainable crop and livestock production system by smallholder farmers.Zuma, Mthokozisi Kwazi.; Odindo, Alfred Oduor.; Everson, Theresa Mary.Livestock play a major role in the livelihoods of smallholder farmers in the rural areas of South Africa. In these areas livestock are continuously grazed in the natural rangelands (veld) for most of the year. This exerts a high grazing intensity on the veld and can result in compaction, soil degradation, increased run-off, loss of palatable grass species, poor veld condition and affect long-term sustainable productivity. In the sour veld areas of the Upper Thukela grazing livestock in the veld in winter is a major problem because the nutritive quality of the grasses is low. The use of fodder crops could provide an alternative and also reduce the pressure on the rangeland to allow a rest period and ensure long-term sustainable productivity. Sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata) are potential crops that could be produced by farmers because they grow under drought conditions and they are nutrient rich crops which can be intercropped. These fodder crops can be fed to livestock in winter and the animal-excreta can be used to produce biogas. Liquid effluent from the anaerobic digestion of the manure and water in the biodigester can be used as organic fertilizer to provide important plant nutrients such as nitrogen (N) and phosphorus (P). There is little information on the use of bioslurry for fodder production in South Africa and the effect on soil chemical properties. The aim of the study was to establish whether bioslurry could be used as a nutrient source for fodder production and secondly, to determine whether this could contribute to sustainable livestock-crop production systems among smallholder farmers in the Upper Thukela, South Africa. The specific objectives were (1) to conduct on-farm trials to determine the effect of bioslurry on growth, biomass and nutritive quality of cowpea and sorghum fodder; (2) to determine the N and P release patterns from bioslurry in two contrasting soils (acidic and non-acidic) sampled from two farms in the Upper Thukela and (3) to assess the impact of using cowpea and sorghum fodder for supplementary feeding on the current grazing carrying capacity (AU ha-1). On-farm trials were conducted at two rural homesteads (New Stand and Potshini) in the Upper Thukela. Growth and yield were measured for both sorghum and cowpea species .Nutritive quality was also analysed for soil and plant samples. No significant differences were observed between MAP, bioslurry and control treatment with respect to growth characters, yield components and nutritive quality in both on farm trials. Sorghum yield in New Stand ranged between 3.75 to 5.47 kg m-2 for the applied treatments (control, bioslurry and MAP), the highest yield was recorded for MAP. Cowpea yield ranged between 4.97 to 6.73 kg m-2 for the applied treatments in New Stand. In Potshini, there were no significant differences on yield. Sorghum yield ranged from 1.8 kg m-2 to 3.09 kg m-2 and cowpea ranged from 3.7 kg m-2 to 5.33 kg m-2. An incubation study was conducted to determine the N and P content and the release patterns from bioslurry in two contrasting soil types (acidic and non-acidic) which represent the soils of the study area. Ammonium-N concentration decreased for all the bioslurry application rates in all the soils (non-acidic, acidic unlimed and limed). There were no significant differences in ammonium-N concentration between the different bioslurry rates applied on the non-acidic soil samples during the 70 day incubation period. Similar results were observed for ammonium-N in the unlimed and limed acidic soils. Results showed that there were no significant differences in nitrate-N concentrations between bioslurry application rates during the incubation period for non-acidic soil. The major findings of this study show that phosphorus increased with the increased application rate of bioslurry. Phosphorus increased with the increase in pH indicating that phosphorus release to the soil is pH dependent. Ammonium-N decreased during the incubation study for all the bioslurry application rates. However, the nitrate-N concentration did not increase which suggests that ammonium-N was not converted to nitrate-N. The case study showed that sorghum and cowpea have potential for the implementation of a semi-zero grazing systems since the higher production of these crops can supplement the low production of the natural rangeland and reduce the grazing pressure on the natural rangeland. The study concluded that although there were no significant differences, bioslurry remain the potential source of organic fertilizer for fodder production in smallholder farming systems.Item Water-use of commercial bamboo species in KwaZulu-Natal, South Africa.(2020) Gumede, Mxolisi Percyval.; Clulow, Alistair David.; Everson, Colin Stuart.; Everson, Theresa Mary.Abstract available in pdf.