Dissertations / Theses on the topic 'Environmental aspects of Hill farming'

Thesis (MA)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: Agricultural and forestry development as well as the erection of buildings and other structures against steep mountain slopes is currently a substantial problem in the Boland. Such developments can be detrimental because of aesthetic considerations and the environmental damage that can arise therefrom. In this regard, environmental damage specifically includes the destruction of fynbos and soil erosion, the latter also having a negative impact on agriculture. This study has attempted to identify areas sensitive to development, and from the resulting findings to develop a set of guidelines for possible future development along the mountain slopes of the Boland. The study area includes only a part of the Boland mountains, namely the Stellenbosch and Hottentotsholland mountains, but can serve as a pilot area for other regions in the Boland possibly plagued by the same problems. Analyses were primarily undertaken by means of GIS software such as inter alia Unix Arc/Info and ArcView 3.1. Various remote sensing techniques were also used to interpret and analyse Landsat TM satellite imagery. For these analyses the image processing program Idrisi for Windows was mainly used. Because the study concentrates on agricultural development, certain criteria such as the erodibility of soil types and the gradient had to be taken into account in the identification of sensitive areas. With regard to gradient data, the use of a "Digital elevation model" (OEM) was of cardinal importance. Other types of development (buildings and structures, as well as forestry) were also analysed to establish firstly where these developments occur; and secondly whether they occur in sensitive areas as far as the height and gradient of slopes are concerned. Because of the subjectivity that exists with regard to the visual impact of these developments, it is difficult to determine what developments on high mountain slopes are aesthetically acceptable and what are not. According to the Act on Agriculture no. 9238 of 1984, slopes with a greater than 20% gradient may not be ploughed without special permission. Against this background the most important result of the analyses undertaken in this study, was the identification of agricultural areas sensitive to erosion. Finally, guidelines are suggested that can be applied to possible future developments on the mountain slopes of the Boland.
AFRIKAANSE OPSOMMING: Landbou- en bosbou-ontwikkeling sowel as die oprigting van geboue en ander strukture teen steil berghellings is tans 'n wesenlike probleem in die Boland. Sulke ontwikkelings kan nadelig wees weens estetiese oorwegings en omgewingskade wat hieruit kan voortspruit. In hierdie verband verwys omgewingskade spesifiek na fynbosvernietiging en gronderosie. Gronderosie het natuurlik ook 'n negatiewe impak op die landbou. Daar is in hierdie studie gepoog om ontwikkelingsensitiewe areas te identifiseer, en vanuit bevindinge 'n stel riglyne te ontwikkel vir moontlike toekomstige ontwikkeling teen die berghellings in die Boland. Die studiegebied sluit slegs 'n gedeelte van die Bolandse berge in, naamlik die Stellenbosch- en Hottentotshollandberge, maar kan dien as loodsgebied vir ander streke in die Boland wat moontlik dieselfde probleme ondervind. Analises is hoofsaaklik gedoen deur middel van geografiese inligtingstelsels- (GIS-) programmatuur soos onder andere Unix Arc/Info en ArcView 3.1. Afstandswaarnemingstegnieke is ook aangewend om Landsat TM- satellietbeelde te interpreteer en te analiseer. Vir hierdie analises is hoofsaaklik van die beeldverwerkingsprogram Idrisi for Windows gebruik gemaak. Omdat die studie op landbou-ontwikkeling konsentreer, moes sekere kriteria soos die erodeerbaarheid van grondtipes en gradiënt in ag geneem word in die identifisering van sensitiewe areas. Wat gradiëntdata betref, was die gebruik van 'n "Digital elevation model" (OEM) van kardinale belang. Ander tipes ontwikkelings (geboue en strukture, asook bosbou) is ook ontleed om eerstens te bepaal waar hierdie ontwikkelings voorkom; en tweedens of hierdie ontwikkelings in sensitiewe areas wat hoogte en gradiënt betref, voorkom. Weens die subjektiwiteit wat rondom die visuele impak van hierdie ontwikkelings bestaan, is dit moeilik om te bepaal watter ontwikkelings teen hoë berghellings esteties aanvaarbaar is en watter nie. Volgens die Wet op Landbou no. 9238 van 1984 mag hellings met 'n gradiënt steiler as 20% nie sonder spesiale toestemming geploeg word nie. Teen die agtergrond hiervan is die belangrikste resultaat van analises in hierdie studie, die identifisering van erosiesensitiewe landbou-areas. Riglyne wat toegepas kan word op moontlike toekomstige ontwikkelings teen die berghellings in die Boland, word laastens voorgestel.

Hong Kong’s agricultural sector has been declining since the 1980s with the reduction in area of arable lands and number of farmers. The trend of over-reliance on imported produce is likely to continue with population growth in the upcoming decades. The climbing imported to locally grown food ratio might aggravate climate change. Vertical farming, which is promoted in recent years as a more sustainable mode of farming than conventional cultivation, is investigated mainly in terms of life cycle Greenhouse gases (GHG) emissions of its produce. Assessment was carried out following the guidelines in two relevant sets of Publicly Available Specification (PAS). Lettuce variety “Heading European”, which is among the most popular leafy vegetables in Hong Kong, is chosen because of its significant share imported from Guangdong Province. Three sets of surveys have been conducted to find out if locally grown produce generates less GHG than imported one. The sustainability of vertical farming is also evaluated. It performs in a cradle-to-gate basis in which life cycle of the lettuce is assessed from the stage of farmland preparation to delivery of them to Vegetable Marketing Organization (VMO). The results of life cycle GHG evaluation show that produce of local farm generates fewer amounts of GHGs than the imported one. For lettuces imported from the conventional farm in Songyuancun, Guangdong Province, it generates approximately 1.57E+00kg of carbon dioxide equivalent (CO2-e). It is about 132% higher than the one grown in local conventional farm at Tai Kong Po Tsuen, which is around 6.77E-01kg of CO2-e It seems the idea of replacing local conventional farming with vertical farming is not sustainable at this stage. Evaluation reveals the latter generates more amount of GHG which is 8.72E+00kg CO2-e/cup of Oak Leaf Lettuce. It is about 13 times higher than the locally grown in the conventional farm. The energy-hungry lighting system and the lack of renewable energy are among the major reasons for high GHG emission in vertical farming. Although the GHG emissions are higher than conventional farming in the designated lifecycle, vertical farming does contribute to sustainable development in terms of food stability and job opportunity. Uncertainties of this study could well be improved by developing a specific set of GHG emission factors for components in preparation stage and on-farm stage. More information could be collected for use and end-of-life stages, which is omitted in the study. Further comparison of wider variety of vegetables cultivated in different forms of farming should also be carried out. Carbon labelling scheme for agricultural products would brush up environmental awareness of both producers and consumers. With the trend of green consumption, it would provide an incentive for producers to adopt this scheme. It is especially important for local vertical farms to impose this scheme to increase its market competiveness. Moreover, government should play a significant role in promoting a more sustainable form of agriculture. Supportive policy like increasing investment in R&D for energy efficient technologies or even erecting a modern building for vertical farms would help achieve this goal. The lowered life cycle GHG emission would enhance sustainability of vertical farming.
published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management

The rapid 1980's development of the salmon farming industry in British Columbia has been called "a poorly defined experiment in a poorly understood coastal environment", and the main impetus behind it described as "the chaotic, bottom-line orientation" not only of the industry itself but also of relevant government policy. The purpose of this thesis is to elaborate on these themes by identifying and delineating the most significant reasoning models underlying government development policy; and to offer an evaluation of the policy's 'rationality'. Throughout the development of the industry, but particularly in the early stages, two major areas of uncertainty have been prevalent. First, detailed government policy towards salmon farming has been far from clear - an inarticulation that is characteristic of the philosophy of laissez faire, which was particularly influential in Canadian government policy in the early 1980's. Secondly, a variety of possible ecological impacts have been suspected from the outset. A heuristic approach, both for the basic method employed in the thesis and for the normative model set up to evaluate government policy, is advanced for addressing these different uncertainties. In order to identify relevant policy, it is hypothesized that systems of ideas expressed formally in 'core' models of neoconservative and neoclassical economics were particularly important policy influences. It is argued that the core concept of neoconservative theory (as defined) is the adaptive efficiency of the autonomous market. The theory's fundamental adaptive ideas - economic information 'discovery' by competitive trial-and-error selection, and consumer 'regulation' via the price system - are to be found in representative federal and provincial economic policy documents from the early 1980's, as well as in the occasional government elucidations of B.C. salmon farming policy (scattered in heterogeneous historical sources). An examination of (inferred) specific decisions relevant to ecological aspects of salmon farming reveals the influence of trial-and-error - deliberate omission of government planning - on early salmon farm siting policy; and the influence of the presumption of consumer 'sovereignty', which was assumed to obviate the need for government ecological regulation. The relevant core concept of neoclassical economics (as defined) is the rational model derived from the conception of homo economicus. The model and its derivations are visible in the same early 1980's economic policy documents, which outline public sector 'restraint' criteria, as well as in salmon farming policy elucidations. It is argued that the maximizing 'solution' prescribed by the model is without operational significance in complex, uncertain situations, where ostensible use of the formal technique may be to legitimate decisions taken on other grounds. The normative model set up to evaluate government policy is drawn from three sources: Friedrich Hayek's rationalization of the adaptive market process, C.S. Holling's prescriptions for "adaptive environmental assessment and management", and Herbert Simon's development of "procedural rationality". These models support the conclusion that acquisition of information by the agency that mediates actions and goals - which, in the case of ecological regulation, must be government - has major value as the basis of more rational decisions. But acquiring conclusive evidence by trial-and-error learning involves risk of serious error, particularly irreversible ecological harm, and it is rational to utilize the inconclusive evidence that is always available for making general predictions, in order to guide search and select lesser risks. Incorporating the important constraint of search costs - particularly significant in the economic recession of the early 1980's - the requirements for rational adaptation become minimal, procedural ones of 'reasonableness': lack of bias towards any class of information relevant to social welfare; lack of denial of uncertainties, and thus of development risks, in the complex and little-known salmon farming environment; and timely response to uncertainties subsequently, adequately resolved by experience. It is suggested that all three requirements were infringed by government policy towards salmon farming development.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

Thesis (MA)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: During the period 2006-2012, the Langkloof area, situated in the Eden District Municipality, suffered severely from environmental shocks and social stress including drought, flooding, hail, wildfire, heatwaves and reduced labour demand. These events negatively impacted many farmers and their livelihoods. In response to these external shocks and stressors, large-, medium- and small-scale farmers adopted numerous coping and adaptive strategies. This study performed a comprehensive livelihoods analysis of large-, medium- and small-scale farmers in the Langkloof area, using the widely recognized sustainable livelihoods framework developed by the United Kingdom’s Department for International Development, with a particular focus on coping and adaptive strategies against severe environmental shock and social stress. Variables used in the analysis were the vulnerability context in which farmers pursue a livelihood; livelihood assets (social, human, financial, natural and physical); the policies, institutions and processes in the external environment that influence the degree of ownership and access to assets; livelihood strategies pursued; and the various livelihood outcomes ultimately produced. The analysis of coping and adaptive strategies employed by farmers during these periods formed an integral part of this study. Sixteen livelihood asset indicators were identified to determine the total assets (human, social, physical, financial and natural) of the farmers. After scaling the indicators, a Principal Component Analysis (PCA) was used to assign weights to each indicator and to subsequently calculate the total assets of each household. Regarding the coping and adaptive strategies employed by farmers against environmental shock and social stress, the average number of strategies was calculated for each household. Spearman’s rank correlations were calculated for total assets achieved (capacity) and the number of strategies employed against environmental shock and social stress.
AFRIKAANSE OPSOMMING: Die Langkloofgedied, geleë in die Eden Distriksmunisipalitiet, is gedurende die tydperk 2006-2012 geweldig geteister deur omgewings- en sosiale gebeure, wat droogte, vloede, hael, veldbrande, hittegolwe en ʼn gevolglike verlaagde arbeidsaanvraag sluit. Hierdie rampe het verreikende nadelige gevolge op boere se lewensbestaan gehad. Terwyl hulle lewensbestaan tot die uiterste uitgedaag is, is verskeie hanterings- en aanpassingstrategieë teen omgewingskok en sosiale stres geïmplementeer. Met die gebruik van die Verenigde Koninkryk se Departement van Internasionale Ontwikkeling se volhoubare lewensbestaansraamwerk is ʼn gedetailleerde en alomvattende analise van groot, medium- en kleinskaalboere in die Langkloof se lewensbestaan gedoen, met ʼn sterk skem op hul hanterings- en aanpassingstrategieë teen omgewingskok en sosiale stress. Die analise veranderlikes het die kwesbaarsheidskonteks waarin boere hul lewensbestaan aanpak; hul verskeie bates (menslik, sosiaal, finansieel, fisies en natuurlik); die beleide, instansies en prosesse in die eksterne omgewing wat toegang tot en eienaarskap van bates reguleer; hul lewensbestaanstrategieë; en die lewensbestaansuitkomste wat bereik word, behels. Die analise van die boere se hanterings- en aanpassingstrategieë geïmplementeer teen omgewingskok en sosiale stres gedurende hierdie tydperk was ʼn integrale rol van hierdie studie. Sestien aanwysers is geïdentifiseer om die totale lewensbestaansbates (menslik, sosiaal, fisies, finansieel en natuurlik) van die boere te bepaal. Nadat die aanwysers geskaal is, is ‘n Hoofkomponentanalise (PCA) uitgevoer om gewigte aan elke aanwyser toe te ken vir die berekening van totale bates van huishoudings. Die hanterings- en aanpassingstrategieë ingestel deur boere teen omgewingskok en sosiale stres, is die gemiddelde aantal strategieë per huishouding. Spearman se rangorde korrelasies is bereken vir die totale bates (kapasiteit) en die getal strategieë geïmplementeer teen omgewingskok en sosiale stres.

This thesis presents the results of research in a small village located in the mountains of Sichuan Province in southwestern China. The thesis argues that traditional irrigation practices vital to paddy-rice production in the village have been stressed by local weather events. It also argues that local villagers have not responded effectively to such changes, and that failure to adjust has contributed to social stress observed at the site. During the earlier years of the study period (1945 to 2012), improvements were made in local irrigation, which seem to have helped farmers continue with traditional subsistence wet-rice farming in a fragile mountain environment. However, in later years of the period village social order showed two significant signs of collapse: first, because of emigration, fewer people were left to farm higher mountain levels so farm land was being abandoned; second, social crowding in lower level riverside farming areas, partly the result of highland emigration, began reducing the amount of land being farmed there. While reducing intensive cropping of highland farming areas can result in spontaneous recovery of natural resources such as soil and water, crowding in lower areas can contribute to deterioration of natural resources in the lower village farmland. Crowding can, in addition, have a bearing on community health problems. The thesis results are of value to researchers concerned with the adaptive behavior of local farming communities trying to maintain their traditional irrigation-dependent way of life in a fragile mountain environment while experiencing the effects of changeable weather. Thesis results are of additional value to those who study the impact on society of earth-warming, especially if variable local weather in the Dabashan is shown to be related to global climate change.

Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Numerous studies indicate that the agricultural sector is physically and economically vulnerable to climate change. In order to determine possible impacts of projected future climates on the financial vulnerability of selective farming systems in South Africa, a case study methodology was applied. The integrated modelling framework consists of four modules, viz.: climate change impact modelling, dynamic linear programming (DLP) modelling, modelling interphases and financial vulnerability assessment modelling. Empirically downscaled climate data from five global climate models (GCMs) served as base for the integrated modelling. The APSIM crop model was applied to determine the impact of projected climates on crop yield for certain crops in the study. In order to determine the impact of projected climates on crops for which there are no crop models available, a unique modelling technique, Critical Crop Climate Threshold (CCCT) modelling, was developed and applied to model the impact of projected climate change on yield and quality of agricultural produce. Climate change impact modelling also takes into account the projected changes in irrigation water availability (ACRU hydrological model) and crop irrigation requirements (SAPWAT3 model) as a result of projected climate change. The model produces a set of valuable results, viz. projected changes in crop yield and quality, projected changes in availability of irrigation water, projected changes in crop irrigation needs, optimal combination of farming activities to maximize net cash flow, and a set of financial criteria to determine economic viability and financial feasibility of the farming system. A set of financial criteria; i.e. internal rate of return (IRR), net present value (NPV), cash flow ratio, highest debt ratio, and highest debt have been employed to measure the impact of climate change on the financial vulnerability of farming systems. Adaptation strategies to lessen the impact of climate change were identified for each case study through expert group discussions, and included in the integrated modelling as alternative options in the DLP model. This aims at addressing the gap in climate change research, i.e. integrated economic modelling at farm level; thereby making a contribution to integrated climate change modelling.
AFRIKAANSE OPSOMMING: Die fisiese sowel as ekonomiese kwesbaarheid van die landbousektor as gevolg van klimaatverandering word deur verskeie studies beklemtoon. ‘n Gevallestudie-benadering is gebruik ten einde die potensiële impak van klimaatsverandering op die finansiële kwesbaarheid van verskillende boerderystelsels te bepaal. Die geïntegreerde klimaatsveranderingmodel bestaan uit vier modelleringsmodules, naamlik: klimaatsverandering, dinamiese liniêre programmering (DLP), interfases en finansiële-kwesbaarheidsontleding. Empiries afgeskaalde klimatologiese data van vyf verskillende klimaatmodelle dien as basis vir die geïntegreerde klimaatsveranderingmodel. Die APSIM gewas-model word aangewend om die impak van klimaatsverandering op gewasse-opbrengs te bepaal. Vir sekere gewasse is daar egter nie modelle beskikbaaar nie en het gevolglik die ontwikkeling van ‘n nuwe model genoodsaak. Die Kritiese Gewasse Klimaatsdrempelwaarde (KGKD) modelleringstegniek is ontwikkel ten einde die impak van klimaatsverandering op die opbrengs en kwaliteit van gewasse te kwantifiseer. Die geïntegreerde klimaatsveranderingmodel neem ook die verwagte verandering in besproeiingswaterbeskikbaarheid (ACRU-hidrologiemodel) en gewas-besproeiingsbehoeftes (SAPWAT3-model) as gevolg van klimaatsverandering in ag. Die model lewer waardevolle resultate op, naamlik: geprojekteerde veranderinge in gewasse-opbrengs en -kwaliteit, geprojekteerde verandering in beskikbaarheid van besproeiingswater en gewasse-besproeiingsbehoeftes, die optimale kombinering van boerdery-aktiwiteite om netto kontantvloei te maksimeer, asook ‘n stel finansiële resultate wat die impak van klimaatsverandering kwantifiseer. Die finansiële kriteria sluit in: interne opbrengskoers, netto huidige waarde, kontanvloeiverhouding, hoogste skuldverhouding en hoogste skuldvlak. Deur middel van deskundige-groepbesprekings is aanpassingstrategieë vir elk van die gevallestudies geïdentifiseer en by die geïntegreerde model ingesluit as alternatiewe opsies in die DLP-model. Die studie poog om die gaping in die huidige klimaatsveranderingnavorsing met betekking tot ‘n geïntegreerde ekonomiese model op plaasvlak aan te spreek en sodoende ‘n bydrae tot geïntegreerde klimaatveranderingmodellering te maak.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Wetlands are key to providing important ecosystem goods and services yet they are under threat from a number of anthropogenic activities. In particular, in this study area, agriculture in the form of sugarcane farming is a threat to wetlands as sugarcane is reliant on a good water supply. The impacts of sugarcane farming emanates from the fact that sugarcane is a mono crop that requires wetland resources and uses a lot of pesticides and fertilisers. Despite the assumed contribution of sugarcane farming to wetland loss and degradation, few studies have quantitatively assessed the spatio-temporal changes in wetland extent as well as changes in water quality because of this activity. This study assesses the impacts of sugarcane farming on wetland extent and water quality in two coastal wetlands of KwaDukuza, North coast of Zululand, South Africa. Specifically this study sought to (i) assess the impacts of sugarcane farming on the spatial extent of wetlands between 1959 and 2012, (ii) determine if sugarcane farming negatively affect water quality within the wetlands and (iii) evaluate the perceptions of local farmers regarding impacts of sugarcane farming on wetlands. Results of the study indicated an increase in the extent of Zinkwazi sugarcane fields from 62.3% to 67% between 1959 and 1989 and Nonoti sugarcane fields’ extent increased from 50.5 % to 56.4% between 1959 and 2000. The last decade from the year 2000 showed gradual decrease in the area of wetland farmed by sugarcane due to the global sugar price remaining static while the cost of farming inputs increased and due to conversion of some farms to urban developments. Unfortunately, this has not lead to an increase in wetland area as the waterfront type developments, as well as a formal settlement have replace the sugarcane in the wetlands. Water was analysed for nitrogen (N), phosphorus (P) and potassium (K) and results for both Zinkwazi and Nonoti indicated an increasing trend of N and P from upstream to the middle region of the rivers and a decreasing trend of the N and P from the middle region to downstream. Sugarcane farming does not take place below the middle region and so does not provide fresh sources of these nutrients. The downstream area where the N and P decrease also coincides with the area of the river under tidal influence such that the N and P are being diluted by the incoming tidal seawater. K showed an increasing trend from upstream to downstream and its values were higher than N and P. Concentrations of N and P above the South African water quality guidelines for aquatic ecosystem were recorded in the middle region. Furthermore, farmers’ perceived wetlands to have been transformed to agricultural land and related these changes to their sugarcane farming activities. It can thus, be concluded that sugarcane farming has resulted in wetland loss as well as deterioration of water quality within the Zinkwazi and Nonoti wetlands in KwaDukuza. In that regard, there isneed to engage farmers in wetland management programs in order to reduce the negative environmental impacts associated with sugarcane farming in wetlands.
AFRIKAANSE OPSOMMING: Vleilande is die sleutel tot die verskaffing van ‘n belangrike ekosisteem dienste, maar hulle is onder ‘n bedreiging deur 'n aantal menslike aktiwiteite. In besonder in hierdie studie area, is Argriculture in die vorm van suikerriet boerdery is bedraging vir vleilande, en suikerriet is afhanklik van 'n goeie watervoorraad. Ten spyte van die veronderstelde bydraes van suikerriet boerdery, is die vleiland aan die agteruitgang, 'n Paar studies het kwantitatief die tydruimtelike veranderinge in die vleiland, sowel as veranderinge in die gehalte van water as gevolg van hierdie aktiwiteit waargeneem. Spesifiek is hierdie studie gepoog om (i) te bepaal wat die impak van suikerriet boerdery op die ruimtelike omvang van die vleiland tussen 1959 en 2012 is, (ii) bepaal of suikerriet boerdery negatief beïnvloed is deur die gehalte van water in die vleilande en (iii) die persepsies van plaaslike boere rakende die evalueering en impak van suikerriet boerdery op die vleilande. Resultate van die studie het aangedui 'n toename in die omvang van Zinkwazi suikerriet velde van 62,3% tot 67% tussen 1959 en 1989, en die Nonoti suikerriet velde toegeneem het met 50,5% tot 56,4% tussen 1959 en 2000. Die laaste dekade van die jaar 2000 het geleidelike afname in die area van die vleilande getoon, omdat suikerriet as gevolg van die globale suiker prys die koste van boerdery-insette verhoog het, en dit het gelei tot die omskakeling van 'n paar plase na stedelike ontwikkelings. Ongelukkig het dit nie gelei tot 'n toename in die vleiland gebiede nie, met die gevolg die waterfront tipe ontwikkelings, asook 'n formele nedersetting, vervang die suikerriet in die vleilande. Water is ontleed vir N, P en K en resultate vir beide Zinkwazi en Nonoti, het aangedui 'n toenemende tendens van stikstof en Fosfor. Dit gaan stroomop na die middel-streek van die riviere en 'n dalende neiging van die N en P uit die middel streek stroomaf. Suikerriet boerdery vind nie plaas onder die middel streek nie, en so is daar nie vars bronne, wat van hierdie voedingstowwe verskaf nie. Die stroomaf gebied waar die N en P ‘n afname het, val ook saam met die gebied van die rivier onder die gety , en dit beinvloed sodanig dat die N en P se water verdun word deur die inkomende gety se seewater. K het 'n toenemende neiging van stroomop en stroomaf en sy waardes is hoër as van die N en P. Konsentrasies van N en P bo die Suid-Afrikaanse water standaard riglyne is in die middel streek aangeteken. Verder, beskou boere dat die vleilande behoort te verander om die landbougrond en verwante veranderinge aan hul suikerriet boerdery en aktiwiteite. Ons kan dus aflei dat suikerriet boerdery het gelei tot die vleiland se verlies asook die verandering in die watergehalte in die Zinkwazi en die Nonoti vleilande in KwaDukuza. In dié verband is dit nodig dat die boere in die vleiland by programme betrek word ten einde die negatiewe omgewingsimpakte wat met suikerriet boerdery gepaard gaan in vleilande te verminder.

Thesis (MSc)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Food demands for the ever-increasing human population is increasing the pressure on the agricultural sector to produce more food. In order to satisfy these demands, farmers are turning to chemical biocides for the control of pest species to produce greater crop yields. All pesticides must be toxic or poisonous to the target species they intend to control. Unfortunately, most pesticides are toxic or poisonous to non-target organisms as well, with detrimental effects on their health. Organic farming was developed to enhance the overall health of the farm's natural soilmicrobe- plant-animal biodiversity. No synthetic fertilisers and/or pesticides are used when farming organically. Life in the soil consists of intricate food webs and interactions between the soil dwelling invertebrates. The soil-organisms are divided into three main groups, viz., Micro-organisms (e.g. protozoa, bacteria and fungi) mesofauna (nematodes, Collembola and Acari) and macro-fauna (e.g. millipedes, isopods, insects, molluscs and earthworms). The invertebrates are very susceptible to chemical contamination by chemical biocides in natural and agro-ecosystems. The soil invertebrate communities are responsible for the decomposition of organic material in soil, thereby remineralising the soil. The decomposition processes start with comminution of the large pieces of organic material by meso- and macro-fauna and ends with the micro-fauna and microbial organisms that complete these processes by returning the nutrients in an inorganic form to the soil. The aim of this study was to investigate whether, and to what extent the soil organisms are influenced by different management practices viz., organic management practices versus conventional management practices. A vineyard on the farm Plaisir de Merle, in Simondium, Western Cape was used for the present study. One half of a one hectare vineyard was managed organically and the other half conventionally. Within each vineyard block six different treatments were performed. Three of the treatments were strictly organic and the other three were strictly conventional. Four replicates of each management treatment were performed. The bait-lamina technique was used to assess the feeding activity of the soil organisms exposed to the different management treatments. In addition to the bait-lamina trials in the vineyard itself, bait-lamina tests were performed in microcosm studies with soil from the organically and conventionally managed vineyard blocks under controlled conditions. In order to assess the impact of the various pesticides that are used in the vineyards in the conventional way, on the soil fauna, standard acute toxicity tests and behavioural tests were performed on Eisenia fetida, the compost worm. The bait-lamina tests in the vineyard revealed that the moisture content of the soil plays an important role in the biological activity of soil fauna. The different management treatments did affect the biological activity of the soil fauna, but seasonal changes also proved to be one of the important factors governing biological processes in the soil. The acute toxicity tests showed that the active ingredients (mancozeb, penconazole and trifloxystrobin) of three of the pesticides that were tested in this study, had negatively affected E. fetida at their recommended application concentrations. The remaining two pesticides' active ingredients (glyphosate and N-acetyl salicylic acid) did not affect the earthworms negatively at the recommended application concentrations. The preference behavioural trials showed that E. fetida could detect and avoid contaminated substrates at the LCso-concentrations of the different pesticides. All the earthworms were influenced positively in the preference behaviour experiments. Because of certain limitations of the bait-lamina technique, it was difficult to formulate conclusions on what happens in the soil. A possible explanation for the differences in feeding activity of soil fauna could be attributed to the migration of the soil fauna to more habitable soil horizons during the dry summer conditions, when most of the pesticides are applied. The ecological relevance of the acute toxicity tests conducted need to be investigated further. It is clear that the acute toxicity tests provided important information that should be considered, but care should be taken and the necessary safety factors be determined and considered when doing risk assessment studies. The results of the preference behaviour studies showed that for certain pesticides E. fetida can be a sensitive bioindicator of acute and/or sub-acute lethal toxicity testing but this might not necessarily be the case for other pesticides. The goal of doing laboratory studies is to gain as much information to make reliable extrapolations to field situations from laboratory data. Laboratory-to-field extrapolations are very complicated because of the physico-chemical composition of soil, the unpredictable way pesticides behave within soil and the reaction of soil organisms to the soil and to the chemical biocides that are used. Further studies need to be done in order to fully understand to what extent the soil fauna were affected by the different management practices applied to the vineyard at Plaisir de Merle.
AFRIKAANSE OPSOMMING: Voedsel aanvraag vir die toenemende menslike bevolking plaas groot druk op die landbou sektor om meer kos te produseer. Om aan die voedsel eise te voldoen, gebruik boere al meer chemiese biosiede om pesspesies te bestry. Alle pestisiede moet toksies of giftig wees vir die teiken organisme waarvoor dit bestem is. Ongelukkig is die meeste pestisiede ook toksies of giftig vir nie-teiken organismes, wat tot nadelige effekte op hul gesonheid kan lei. Organiese boerdery is ontwikkel om die algehele gesondheid van die plaas se natuurlike grond-mikrobe-plant-dier biodiversiteit te bevorder. Geen sintetiese bemestingstowwe en/of pestisiede mag gebruik word wanneer daar organies geboer word nie. Die lewe in die grond bestaan uit ingewikkelde voedselwebbe en interaksies tussen die grondlewende invertebrate. Die grond invertebrate word verdeel in drie hoof groepe, nl. mikro-organismes (bv. Protozoa, bakterieë en fungi) meso fauna (Nematoda, Collembole en Acari) en makrofauna (bv. Millipoda, Isopoda, Insecta, Mollusca en erdwurms). Die Invertebrata is die mees vatbaarste vir chemiese kontaminasie deur chemiese biosiedes in natuurlike en landbou ekosisteme. Die grond invertebraat gemeenskappe is verantwoordelik vir die afbreek van alle organiese materiaal in die grond en dus vir remineralisering van die grond. Die afbreekproses begin by die komminusie van groter stukke organiese materiaal deur die meso- en makrofauna en eindig met die mikrofauna en mikrobes wat die prosesse voltooi deur die nutriente terug te plaas in die vorm van anorganiese produkte in die grond. Die doel van hierdie studie was om te ondersoek of, en tot watter mate, grond organismes geraak word deur verskillende grondbestuurspraktyke, nl. Organiese grondbestuurspraktyke teenoor die konvensionele grondbestuurspraktyke. 'n Wingerd op die plaas Plaisir de Merle, in Simondium, Wes-Kaap, was gebruik vir die huidige studie. Een helfte van 'n een hektaar wingerd is organies bestuur en die ander helfte is op die konvensionele manier bestuur. Op elk van die twee wingerd blokke is ses verskillende behandelings toegepas. Drie van die behandelings was streng organies en die ander drie was streng konvensioneel van aard. Vier replikate van elke behandeling is toegepas op elk van die twee wingerdblokke. Die bait-lamina metode is gebruik om die voedingsaktiwiteit van die grond organismes te asses seer. As toevoeging tot die bait-lamina proewe in die wingerd self, is bait-lamina toetse ook in mikro-kosmosse in die laboratorium gedoen met grond afkomstig vanaf die twee wingerdblokke. Om die impak van die verskillende pestisiede op die grondorganismes te ondersoek, is standaard akute toksisteitstoestse en gedragstoetse uitgevoer met die komposerdwurm, Eisenia fetida. Die bait-lamina resultate in die wingerd het getoon dat die voginhoud van die grond die belangrikste rol speel wat die biologiese aktiwiteit van die grondorganismes beïnvloed. Die verskillende behandelings het die biologiese aktiwiteit van die grond fauna geaffekteer, maar seisoenale veranderings is ook uitgesonder as een van die bepalende faktore wat die biologiese prosesse in die grond stuur. Die akute toksisiteitstoetse het getoon dat die aktiewe bestandeie van drie van die pestisiede (mancozeb, penconazole en trifloxystrobin), E. fetida negatief beïnvloed het teen die aanbeveelde konsentrasies wat toegedien is. Die aktiewe bestandeie van die ander twee pestiede (glyphosate en N-asetiel sallisiel suur) het nie die erdwurms nadelig beïnvloed teen die aanbeveelde konsentrasies wat toegedien is nie. Die gedragsproewe het getoon dat E. fetida die LCso-konsentrasies van al die verskillende pestisiede kan waarneem en vermy. Al die erdwurms is positief beïnvloed in die gedragseksperimente met die verskillende pestisiede. Omdat die bait-laminametode sekere beperkings het, was dit moeilik om tot gevolgtrekkings te kom oor wat presies in die grond gebeur. 'n Moontlike verklaring vir die verskillende voedingsaktiwiteite van die grond fauna kan toegereken word aan die migrasie van die grondorganismes na meer leefbare grondhorisonne gedurende die droë somer toestande, wat toevallig met die spuit van die meeste pestisiede ooreenstem. Die ekologiese relevansie van die akute toksisiteitstoetse wat uitgevoer is, moet meer deeglik ondersoek word. Die belangrikheid van die akute toksisteitstoetse is duidelik en het waardevolle informasie gelewer, maar sorg moet geneem word, en die nodige veiligheids faktore moet bepaal word en in ag geneem word, wanneer riskobepalingstudies gedoen word. Die gedragsproewe het getoon dat vir sekere pestisiede E. fetida 'n sensitiewe bioindikator van akute en/of sub-akute letale toksisiteits toetse kan wees, maar nie noodwendig vir ander pestisiede nie. Die doel van laboratoriumstudies is om so veel as moontlik inligting te versamelom vertroubare ekstrapolasie te kan maak na situasies in die veld vanaf laboratorium data. Laboratorium-na-veld ekstrapolasies is dikwels baie gekompliseerd as gevolg van die fisies-chemiese samestelling van die grond, die onvoorspelbare manier waarop chemiese pestisiede met die grond reageer en die reaksie van die grondorganismes op chemiese biosiede in die grond. Verdere studies moet gedoen word om so deeglik maanlik die mate van die impak wat die verskillende bestuurspraktyke op die grond fauna het, te verstaan op Plaisir de Merle.

Agriculture is key to New Zealand�s economy with land-use conversions in response to market forces occurring regularly. Recently, high-intensity dairy farming has replaced low-density livestock farming, often degrading surrounding waterways. Of particular concern is that dairy cattle can be a source of the parasite Giardia, which in humans is a common cause of gastrointestinal infection. Thus, this thesis evaluated whether dairy farm conversions posed significant consequences for public health. First I examined the prevalence of Giardia in calves in a rapidly intensifying dairying region of New Zealand. A total of 1190 faecal samples were collected from calves one to seven weeks old during two spring calving seasons and screened by direct immunofluorescent microscopy. Giardia cysts were detected in 31% of samples. To evaluate the potential risk that this environmental source of Giardia posed to the human population, molecular genotyping was used to compare forty Giardia strains isolated from calves with thirty isolates from humans collected in the same region and period. Sequencing the β-giardin gene, Giardia duodenalis assemblages A and B were identified from both hosts, with genotype comparisons revealing substantial overlap of identical genotypes for both assemblages, implying zoonotic transmission. Environmental agencies routinely promote the planting of streamside edges to decrease nonpoint pollution from dairy farms entering waterways. However, current methods for tracking pathogens across farmland and into waterways via surface runoff are limited and typically have been developed using artificially created landscapes. Furthermore, no studies have investigated how Giardia moves across the landscape in farm surface runoff. I developed a field-based tracking method specific for Giardia and used this technique to compare the ability of recently planted vegetation strips with bare soil strips cleared of vegetation at decreasing pathogen concentrations; a typical scenario when planting barriers to reduce waterway contamination. A spike containing a bromide tracer and inactivated Giardia cysts was applied in drip-irrigated surface runoff, with one-minute samples collected from the bottom of the plot. A significant treatment effect was identified for Giardia, with 26% fewer detected in runoff from the planted strip, highlighting the immediate benefit of vegetation planting in removing pathogens. Next I evaluated the effects of four riparian treatments on Giardia runoff: exotic pasture grass and weeds growing in the absence of cattle grazing due to fencing, in comparison to monocultural plantings of three New Zealand native grassland species. Runoff experiments were performed after planting, both prior to and following the main summer growing season. Bromide recovery was high from all four treatments (54 - 99%), with no significant treatment effects. By comparison, Giardia recovery was low (1 - 13%). Prior to summer, two native species reduced Giardia in runoff more than the pasture grass/weed treatment which was almost vegetation-free at this time. After summer, Giardia recoveries were uniformly lower in all treatments. These results demonstrate that after one growing season, fencing waterways produces riparian buffers, via the growth of exotic pasture plants released from grazing, that decrease pathogen concentrations in surface runoff to concentrations indistinguishable from native plantings. Given infectious organisms are known to be in the environment, it is important to assess the risk these pose to human populations. Findings from this research can be used to improve currently available risk-assessment models for Giardia transmission from infected dairy animals via water to humans.

A agricultura brasileira desenvolve um papel muito importante na economia nacional e melhorar os processos de produção é algo que se busca continuamente. Métodos que auxiliem o manejo adequado das culturas visando uma maior produtividade e redução de custos é algo imprescindível para uma agricultura mais competitiva. O controle de plantas invasoras está entre os fatores que mais influenciam na lucratividade de uma cultura, pois se realizada de modo ineficiente, pode inviabilizar a atividade. O uso de sensores que automatizam alguns dos diversos processos realizados no campo vem tomando força na agricultura moderna e contribuindo para as produções recordes registradas atualmente, mas que na maioria dos casos são inacessíveis a grande maioria dos produtores. Neste trabalho foi desenvolvido um protótipo que automatiza o processo de aplicação controlada de herbicida, com um custo 13,53% em relação aos principais equipamentos comerciais que realizam tal função. Trata-se de um equipamento desenvolvido com hardware e software livre, que realiza a captura e processamento digital de imagens, promovendo a identificação de plantas invasoras e aplicação localizada de herbicidas não seletivos. A coleta das imagens é realizada por uma webcam controlada pela placa Raspberry, que também realiza o processamento digital destas imagens com o auxílio do software Opencv. O equipamento possui também uma válvula solenoide que controla o fluxo de herbicida. Toda a construção e testes foram realizados no município de Vera Cruz do Oeste, no Paraná. A velocidade máxima obtida nos testes foi de 4 km/h, pouco se comparado aos 25 km/h dos equipamentos comerciais, detectando plantas com área folhar com no mínimo 3 cm², um resultado muito semelhante aos principais equipamentos comerciais presentes no mercado. Apresar da baixa velocidade de operação, o equipamento se mostrou viável em sua utilização, pois pode gerar lucro com a economia de herbicida em aproximadamente dois anos, dependendo da área e grau em que se dá a utilização do equipamento.
Brazilian agriculture plays a very important role in the national economy and improving the production processes is something that is continuously sought. Methods that help the proper management of crops for greater productivity and cost reduction are essential for a more competitive agriculture. The control of invasive plants is among the factors that most influence the profitability of a crop, because if it is carried out in an inefficient way, it can make the activity unfeasible. The use of sensors that automate some of the various processes carried out in the field has been taking hold in modern agriculture and contributing to the record productions currently recorded, but in most cases are inaccessible to the great majority of producers. In this work a prototype was developed that automates the process of controlled application of herbicide, with a cost of 13.53% in relation to the main commercial equipment that perform such function. It is an equipment developed with hardware and free software, which performs the digital capture and processing of images, promoting the identification of invasive plants and localized application of non-selective herbicides. The images are collected by a webcam controlled by the Raspberry card, which also performs the digital processing of these images with the help of Opencv software. The equipment also has a solenoid valve that controls the flow of herbicide. All the construction and tests were carried out in the municipality of Vera Cruz do Oeste, Paraná. The maximum speed obtained in the tests was of 4 km / h, little compared to the 25 km / h of commercial equipment, detecting plants with leaf area with at least 3 cm², a result very similar to the main commercial equipment present in the market. In order to achieve a low operating speed, the equipment proved to be viable in its use, since it can generate profit from the herbicide economy in approximately two years, depending on the area and degree of use of the equipment.

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Water storage in reservoirs forms an integral part of the agricultural landscape in the Western Cape Province, South Africa. A few large reservoirs serve primarily as a drinking and industrial water supply, while on private farms, small reservoirs provide irrigation water for the dry summer period. Protection of water quality to secure irrigation and drinking water quality, and the extension of water use efficiency are priority issues in the Western Cape. In the current study, the suitability of rainbow trout (Oncorhynchus mykiss) cage farming as a non-abstractive water use was investigated. The current study concentrated on the identification, and where possible quantification of aquaculture impacts, the identification of successful sites and a description of requirements in which net-cage aquaculture has none or a very low negative impact on water quality (e.g. <15 % change from previous water quality conditions for phosphorus concentrations). In order to study the effects of 5 t trout cage production units in reservoirs <15 ha in area, the general ecology of the irrigation reservoirs was assessed. Sixteen reservoirs without aquaculture production (reference reservoirs) were compared to 26 reservoirs with aquaculture production (production sites with varying production histories). Catchment characteristics were also monitored. Water from different depths (0 m, 2 m, 6 m and near bottom) was tested for physical and chemical qualities as well as nutrient concentrations. Phytoplankton and zooplankton biomass and species composition was monitored. In addition to the general phytoplankton findings, cyanophytes were evaluated for their contribution to algal taint problems that emerged at a number of production sites. Sediments were tested for total phosphorus content and phosphorus release capacity. Indicators and minimum conditions to avoid the most common production problems were formulated. In order to determine long-term production success, which prevents trophic level changes of reservoirs, a mass balance approach (nutrient budget) was employed to indicate the limits for nutrients that can be added. The phosphorus balance indicated long term trends for reservoirs with and without aquaculture. The detailed mass balance approach was compared to a “ready to use” carrying capacity model that estimated the maximum fish load each reservoir could support. The anthropological input of phosphorus into the reservoirs causes a decreasing water quality in the studied reservoirs and this development was also reported for lowland rivers. Twenty percent of the studied reservoirs are in a condition that could be an immediate threat to fish or water bird health (e.g. free ammonia concentrations and pH). Harmful algal blooms were not observed. Aquaculture production evoked changes in water chemistry and ecology in most of the studied reservoirs. Adverse effects of aquaculture sites versus non-aquaculture sites were: increased phytoplankton biomass and species shifts towards sizes >80 μm. The increased phytoplankton abundance influenced pH maxima to values >9 at mid-day. The high pH fluctuations were greatly influenced by the naturally low alkalinity and hence low calcium buffering capacity of Western Cape waters. The deoxygenation of the hypolimnion during stagnation (summer) occurred faster in reservoirs of certain character, greatly dependent on elevation and surface area, with consequent acidification of the hypolimnion, as well as ammonia and total phosphorus (TP) accumulation. In this context, a diversity of each reservoir with and without aquaculture production, with a similar ratio of undisturbed reservoirs to reservoirs with influence of e.g. agriculture, were compared to each other. When grouping the respective differences from the average reference reservoir (i.e. no trout production), a low impact on water quality was manifested at four sites (15 %) with <15 % increase of bottom TP and ammonia, while eight sites (31 %) showed medium effects (59 % mean increase), and a high impact was found at 54 % of the sites (312 % mean increase). In reservoirs without aquaculture, the extent of incoming phosphorus (which could represent an influence by runoff from agricultural land) was very high. However, in small reservoirs (<5 ha), these values were exceeded by the incoming phosphorus from aquaculture practices. In the case of small reservoirs where the carrying capacity was clearly surpassed, effects caused by aquaculture were severe and the assimilation of waste by the system was not possible (in extreme cases aquaculture waste delivered 60 to 90 % of all incoming phosphorus – two to nine times the phosphorus brought in by rivers and runoff). With regards to sediment, only indirect conclusions could be drawn. Aquaculture production increased hypolimnetic anoxia and the latter was shown to increase potential phosphorus release from sediments. This implies that not only will aquaculture increase the phosphorus concentration of surface waters directly, but it will also increase internal loading. The sedimentation rate was increased with cage aquaculture which affects a hypothesized area of approximately 0.2 to 1.0 ha depending on reservoir hydrology. The composition of the sediment increased organic components which can impact on sediment processes. It can be postulated that increased sedimentation of aquaculture waste and extended anoxic conditions impact on macrozoobenthos. Hydrological and nutrient mass exchange of the reservoirs indicated that no annual increase of phosphorus was achieved with low nutrient input (good inflowing water quality) or good water exchange (>5 times per year), and sometimes with extraction of hypolimnetic water during the stagnation period (summer). A model developed by Beveridge (1984) showed similar results to the mass balance approach and can therefore serve as a more ready model to determine suitable stocking rates. The small (man-made) reservoirs in the Western Cape are in a eutrophication process which far exceeds the speed of natural eutrophication (trophic states indicating highly eutrophic or hypertrophic conditions after approximately 10 to 20 years following construction of the reservoirs) and this process is triggered by agricultural practice (indicated by literature – not a subject of this study). However, it is concluded from the data of this study that trout-cage aquaculture duplicated the total phosphorus already present (independent of continuation of the projects, the phosphorus introduced was trapped in the closed systems the reservoirs represent) in only 1 to 2 years of production - which means a significant acceleration of the eutrophication process already in place. There are positive exceptions where trout-cage production is possible without negative effects. Careful site selection is the most important step in successful and sustainable trout production. No impact of aquaculture was recorded at four reservoirs (15 % of the investigated reservoirs) which shared the characteristics of good water exchange (>3 times per year) and a minimum surface area of 5 ha. Additionally, criteria that reduced the risk of algal taint included a minimum water depth of 6 to 7 m in a reservoir at its lowest water point (to avoid intermediate mixing during the stagnation period) as well as cold hypolimnetic conditions (<17 °C) to minimize cyanophyte cyst remobilization. Further improvement of food conversion ratio (feeding management) and feed quality are the next (after site selection) two most important components that determine if a reservoir can be utilised for cage production without any long-term changes. There is potential in advances in feed quality, feed management and waste collection systems. These measures (e.g. the cage size could be decreased to efficate feeding management) can increase the number of sustainable sites and achieve multiplication of water use without water quality deterioration.
AFRIKAANSE OPSOMMING: Die stoor van water in reservoirs vorm ‘n integrale deel van die landboulandskap in die Westelike Kaap gedeelte van Suid-Afrika. ‘n Aantal groter reservoirs voorsien primêr water primer vir drinkdoeleindes en vir aanwending deur industrieë, terwyl kleiner reservoirs op private plase gebruik word vir besproeiing gedurende die droë somerperiode. Die beskerming van die waterkwaliteit en die uitbreiding van watergebruik se doeltreffendheid, word bestempel as ‘n prioriteit vir die Wes-Kaap. In die huidige studie is die geskiktheid van forel hokkultuur as ‘n bykomende watergebruik, maar sonder waterverbruik, ondersoek. Die huidige studie fokus op die identifisering en waar moontlik die kwantifisering van die impak van akwakultuur op besproeiingsreservoirs; die identifisering van potensiële reservoirs vir akwakultuur; en die beskrywing van toestande waarin akwakultuur geen of ‘n baie lae negatiewe uitwerking op die waterkwaliteit (bv. < 15 % verandering vanaf oorspronklike waterkwaliteitstoestande vir fosforkonsentrasies) sal hê. Om die impak van 5 t forel hokproduksie eenhede in <15 ha reservoirs te bestudeer, is die algemene ekologie van die besproeiingsreservoirs bepaal. Watermonsters, geneem op verskillende dieptes (0, 2, 6 en naby die bodem), is getoets vir fisiese- en chemiese kwaliteit sowel as vir die nutriëntkonsentrasies. Die biomassa en spesiesamestelling van fitoplankton sowel as zooplankton is gemonitor. Sestien verwysingsreservoirs is vergelyk met 26 produksiereservoirs (met wisselende vlakke van produksiegeskiedenis). Die karakeristieke eienskappe van die opvangsgebied is ook gemonitor. Tesame met die algemene fitoplankton bevindinge, is blougroen alge ook geëvalueer vir hul bydrae tot algae besmettingsprobleme wat voorgekom het by ‘n aantal produksie persele. Sedimente is getoets vir die totale fosforinhoud en fosforvrystellingskapasiteit. Perseelseleksie is geidentifiseer as een van die mees belangrikste faktore vir suksesvolle hokproduksie. Indikatore en minimum toetstande wat vereis word om die mees algemene produksieprobleme te verhoed, is geformuleer. Om die langtermyn produksie sukses te bepaal, wat trophiese vlakke se verandering in die reservoirs verhoed, is ‘n massa balans benadering (nutriënt balans) gebruik. Die fosfor balans het langtermyn tendense aangetoon en in die geval van die produksie reservoirs, is die akwakultuurimpak gekwantifiseer. Die gedetaileerde massa balans benadering is vergelyk met ‘n “gereed om te gebruik” drakapasiteitsmodel wat die maksimum vis wat die reservoir kan onderhou, geskat het. Die antropogeniese toevoer van fosfor na die reservoirs veroorsaak ‘n afname in die waterkwaliteit van die reservoirs wat bestudeer is. Die verskynsel van ‘n afname in waterkwaliteit is ook vir verskeie laagliggende riviere geraporteer. Sowat 20 % van die besproeiingsreservoirs wat bestudeer is, is tans in ‘n toestand wat die onmiddelike gesondheid van vis en watervoëls kan bedreig. Skadelike algebbloei is nie waargeneem nie. Akwakultuurproduksie het negatiewe effekte getoon in ‘n aantal reservoirs. Die nadelige uitwerking van akwakultuur waar digthede te hoog was, is: toename in fitoplankton biomassa en spesiesverskuiwinge. Die toename in fitoplankton teenwoordigheid het die pH maxima beïnvloed tot waardes >9 teen 12 uur middag. Die hoë pH fluktuasies is grootliks beïnvloed deur die natuurlike lae alkaliniteit en gevolglike kalsium bufferkapasitiet van die Wes-Kaap se waterbronne. Die deoksiginasie van die hipolimnion gedurende stagnasie (somer) het vinniger plaasgevind in oorbelaaide reservoirs, met gevolglik ‘n versuring van die hipolymnion, sowel as die akkumelering van ammoniak en totale fosfor. In hierdie konteks word reservoirs met en sonder landbouproduksie, met ‘n gelyke verhouding van onversteurde reservoirs tot reservoirs wat deur landboubedrywighede beinvloed word, met mekaar vergelyk. By vier persele (15 %) is ‘n lae impak vasgestel (<15 % toename in bodem TF en ammoniak), terwyl agt persele (31 %) ‘n medium impak getoon het (59 % gemiddelde toename in bodem TF en ammoniak) en ‘n hoë impak is opgemerk by 54 % van die persele (31 % gemiddelde toename in bodem TF en ammoniak). In reservoirs sonder akwakultuur, was die omvang van fosforinvloeiing baie hoog en is moontlik veroorsaak deur die invloei van afloopwater uit omliggende landbougebiede. Alhoewel in klein reservoirs (<5 ha) was hierdie waardes oorskadu deur die invloeiing van fosfor deur akwakultuur praktyke.In die geval van klein reservoirs, waar die drakrag duidelik oorskry is, was die gevolge, soos veroorsaak deur akwakultuur ernstig, en die assimilasie van afval deur die sisteem nie moontlik nie. In die uiterste gevalle het akwakultuurafval 60 % - 90 % van alle inkomende fosfor gelewer - twee tot nege maal die fosfor wat deur riviere en afloopwater ingevloei het. Wat die sediment aanbetref, kon slegs indirekte gevolgtrekkings gevorm word. Akwakultuurproduksie het hipolimnetiese anoksia laat toeneem en die laasgenoemde verskynsel, het die potensiaal aangedui vir die toename in die vrystelling van fosfor vanaf die sediment. Dit dui daarop dat akwakultuur nie alleen die fosforkonsentrasie in die oppervlaktwater laat toeneem nie, maar sou ook die interne belading laat kon toeneem. Die sedimentasie tempo het toegeneem met die teenwoordigkeid hokkultuur en het ‘n hipotetiese area van ongeveer 0.05 tot 1.00 ha, afhangende van reservoir hidrologie, beïnvloed. Die samestelling van die sediment het toegeneem in teme van die organiese komponente wat die sedimentasie prosesse kon beïnvloed. Dit kan gepostuleer word dat die toename in sedimentasie van akwakultuurafvalprodukte tesame met verlengde anoksiese toestande, ‘n invloed op die makrosoöbentiese organismes het. Hidrologiese en nutriënt massa uitruiling van die reservoirs het aangetoon dat geen jaarlikse toename in fosfor verkry kan word met lae nutrient toelae (kwaliteit van invloeiende water) of met goeie waterverplasing nie, en soms met die ekstraksie van hipoliminetiese water gedurende die stagnasie periode (somer). Die Beveridge model het soortgelyke resultate getoon tot die massabalans benadering en kan daarom dien as ‘n meer aanvaarbare model om gepaste beladingstempo vas te stel. Kleiner mensgemaakte reservoirs in die Wes-Kaap is onderhewig aan ‘n eutrofikasie proses wat die spoed van natuurlike eutrofikasie (trofies verwys na ‘n hoogs eutrofiese of hipertrofiese toestand ongeveer 10 tot 20 jaar na reservoir konstruksie) oorskry. Literatuur (nie ondersoek in die huidige studie) dui aan dat hierdie versnelde eutrofikasie proses meegebring word deur landbouaktiwiteite in die opvangsarea van die reservoirs. Resultate van die huidige studie het getoon dat forelproduksie in hokstelsels, die konsentrasie van total fosfor wat reeds beskikbaar was, verdubbel het. Die toename in fosforkonsentrasie het binne 1 tot 2 jaar na die aanvang van forelproduksie in die betrokke reservoirs, plaasgevind. Daar is egter uitsonderings waar forelproduksie in hokstelsels moontlik was, sonder die gepaardgaande afname in die waterkwaliteit. Die belangrikste stap vir suksesvolle en volhoubare forelproduksie is deeglike perseelseleksie. Daar is geen impak van akwakultuur waargeneem by vier persele (15 %) wat die eienskappe van goeie waterverplasing (>3 keer per jaar) en ‘n minimum oppervlakarea van 5 ha gehad het nie. Bykomend, sluit kriteria wat die risiko van algbesmetting laat afneem, ‘n minimum waterdiepte van 6 tot 7 m in ‘n reservoir by die laagste punt in (om te verhoed dat intermediêre vermenging plaasvind gedurende die stagnasieperiode) sowel as koue hipolimnetiese toestande (<17 °C) om sianobakterieë sist remobilisasie te minimaliseer. Verdere verbetering van die VOH (voeromsettingsverhouding onder voedingsbestuur) en voerkwaliteit is na perseeleleksie, die volgende komponente wat kan aandui of ‘n perseel gebruik kan word vir hokkultuur sonder enige impak. Vordering met voerkwaliteit en voedingsbestuur kan die aantal volhoubare persele laat toeneem en daardeur meer effektiewe watergebruik teweeg bring, sonder die verwante waterkwaliteit verswakking.

Thesis (MScAgric (Agricultural Economics))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The rising demand of fish due to population growth coupled by stagnation of fish supply from natural capture has led the world to turn to aquaculture to fill in the gap between fish supply and demand. Aquaculture has emerged as the only sustainable way of supplying the rising population with fish. However the rapid expansion of aquaculture has been met with growing concerns over its environmental effects especially waste produced from aquaculture. The net cage system that is currently being used by small scale trout farmers in the Western Cape is an open water based system where release of waste into the water bodies is inevitable and this put into question the long term sustainability of trout farming using net cages in irrigation dams in the Western Cape. This study sought to compare identified production techniques that can be used by aquaculture farmers to reduce accumulation of organic waste in irrigation dams. The proposed ‘clean’ production techniques include use of net cages fitted with Lift-up system, semi intensive floating tank system (SIFTS) and intergrated aquaculture systems. The study revealed that the intergrated aquaculture system is the most effective way of recovering waste that shows great potential of moving aquaculture towards long term sustainability as it fullfills sustainability dimensions such as ‘zero emission’, nutrient recycling and integrated production. Mechanical methods of recovering waste such as Lift-up system and SIFTS are also effective in recovering particulate waste but however dissolved nutrients are lost into the environment. The study went on further to investigate if economic, environmental and social benefits of recovering waste from irrigation dams outweigh the costs of recovering waste using different production techniques. Models of small scale aquaculture farms using the three identified production techniques were developed and compared with a modelled small scale net cage farm where there was no waste recovery. A comparative financial analysis of the modelled small scale trout farms using alternative production techniques carried out showed that trout production using any of the three alternative ‘clean’ production techniques is financially viable with the SIFTS production technique giving the farmer the highest returns, followed by the intergrated system, then the net cage with a Lift-up system and lastly the net cage system without waste recovery. The second part of the study used the contingent valuation method to estimate the environmental and social benefits of removing waste from dams. Households revealed that they were willing to pay (WTP) R40 on average annually to improve water quality from a state where eutrophication had occurred to a state suitable for irrigation and aquaculture. To improve water quality from a state suitable for irrigation to a state suitable for swimming, households were willing to pay R16.67 annually. If water was to be improved from a state suitable for irrigation to a level suitable for domestic purposes, average willingness to pay (WTP) was R26.17 annually. WTP indicate that besides financial benefits associated with using ‘clean’ production techniques there are environmental and social benefits that will arise to the farm community using water from the irrigation dams.
AFRIKAANSE OPSOMMING: Die stygende vraag na vis as gevolg van bevolkingsgroei, tesame met die stagnering van die aanbod van vis vanaf natuurlike vangste het daartoe aanleiding gegee dat die oë van die wêreld op akwakultuur gerig is om die gaping in die voorsiening van vis te vul. Akwakultuur het ontwikkel as die enigste volhoubare manier om aan die groeiende vraag na vis te voldoen. Die vinnige uitbreiding van akwakultuur het egter toenemende besorgdheid in die nadelige omgewingsimpak, veral ten opsigte van akwakultuurafval, tot gevolg gehad. Die nethokstelsel wat tans deur kleinskaalse forelboere in die Wes-Kaap in oop watergebaseerde sisteme gebruik word en die vrystelling van afval in die wateromgewings wat onafwendbaar is, plaas ’n vraagteken oor die langtermyn volhoubaarheid van die nethokstelsel forelboerdery in besproeiingsdamme in die Wes- Kaap. Die studie het ten doel gehad om geïdentifiseerde produksiestelsels wat deur akwakultuurboere gebruik kan word om die akkummulasie van organiese afval in besproeiingsdamme te verminder, te vergelyk. Die voorgestelde “skoon” produksietegnieke sluit in nethokke wat aan ’n opligstelsel gekoppel word, ‘n semi-intensiewe drywende tenk- stelsel (“SIFTS system” in Engels) en ‘n geïntegreerde akwakultuurstelsel. Met hierdie studie is bevind dat die geïntegreerde stelsel die mees effektiewe manier is om afval te herwin en toon potensiaal om akwakultuur op ’n vohoubare pad te plaas aangesien dit aan die volhoubaarheidsdimensies van geen emissie, voedingstofherwinning en geïntegreerde produksie voldoen. Meganiese metodes van afvalherwinning soos die nethokopligstelsel en die SIFTS-stelsel is effektief in die herwinning van vastestofdeeltjies, maar opgeloste voedingstowwe word steeds in die omgewing vrygestel. Die studie het voorts ten doel gehad om te bepaal of die ekonomiese, omgewings- en sosiale voordele om afval uit besproeiingsdamme te herwin, groter is as die herwinningskoste van die verskillende produksietegnieke. Modelle van kleinskaalse akwakultuurplase wat die drie geïdentifiseerde produksiestelsels gebruik, is ontwikkel en aangewend om te vergelyk met ’n nethokstelsel waar geen afvalherwinning gedoen word nie. ’n Vergelykende finansiële ontleding van die gemodelleerde kleinskaalse forelboerderye met die verskillende produksietegnieke is gedoen en daar is bevind dat enige een van die drie “skoon” stelsels finansieel lewensvatbaar is, met die SIFTS-stelsel wat die hoogste vergoeding aan die boer bied, gevolg deur die geïntegreerde stelsel, dan die nethokke aan ’n opligstelsel en dan die nethokstelsel sonder afvalherwinning. Die tweede deel van die studie het van die voorwaardelike (“contingent”) waardasiemetode gebruik gemaak om die omgewings- en sosiale voordele om afval uit besproeiingsdamme te verwyder, te bepaal. Huishoudings het aangetoon dat hulle bereid sou wees om tot R40 per jaar te betaal om die waterkwaliteit te verbeter vanaf ’n toestand waar eutrifikasie plaasgevind het na ’n toestand waar die water vir besproeiing en akwakultuur geskik sou wees. Om die waterkwaliteit vanaf ’n toestand geskik vir besproeiing te verander na ’n toestand geskik om in te swem, sou huishoudings bereid wees om R16.67 per jaar te betaal. Indien water vanaf ’n toestand geskik vir besproeiing verander sou word na ’n toestand geskik vir huishoudelike gebruik, sou huishoudings gewillig wees om jaarliks R26.17 te betaal. Die “gewilligheid om te betaal” dui aan dat daar bo en behalwe die finansiële voordele om van “skoon” produksietegnieke gebruik te maak, ook omgewings- en sosiale voordele vir die plaasgemeenskap bestaan met die gebruik van die water uit die besproeiingsdamme.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2007.
Small farm dams (< 20 ha) in the Western Cape Province provide adequate water conditions for intensive cage production of rainbow trout (Oncorhynchus mykiss). A major environmental concern of cage aquaculture, however, is the high inputs of nutrients via commercial diets and the subsequent eutrophication of the water source. Eutrophication can result in the degradation of the general water quality (increasing pH levels, oxygen depletion, increased hydrogen sulphide and free ammonia) and shifts in the phytoplankton structure (increased biomass, single species dominance). Deterioration of water quality will affect the success of the fish farming enterprise as well as the performance of irrigation equipment by increasing the risk of clogging and corrosion. Water quality, phytoplankton and zooplankton compositions were monitored at four sites from June 2005 to November 2006 to determine the effects of cage culture on the farm dam environment, its associated biota as well as irrigation water quality. The distribution of nutrients, nitrogen and phosphorus, was mainly influenced by the stratification and mixing regime of the water bodies. Nutrient concentrations increased during the winter mixing period while in the summer months, they seem to settle to the lower part of the water column. Nutrient concentrations of production sites and reference sites were comparable except for the ammonia levels that were significantly higher at the production sites. Phytoplankton corresponded with nutrient availability resulting in high biomass during winter. In terms of biomass, phytoplankton was approximately two times more abundant in production sites compared to reference sites. Assemblage dominance by cyanophytes (Anabaena circinalis, Microcystis spp.) was found more often in production sites, while reference sites were dominated by dinophytes (Ceratium hirundinella, Peridinium spp.). Zooplankton biomass concurred with high phytoplankton biomass in winter. Zooplankton assemblages in production sites sustained much higher biomass. Effects of cage culture on irrigation water quality are evident from increased algal biomass and shifts in species composition. These results indicated that at its present production level, cage culture had impacts on the farm dam environment and irrigation water quality. The most significant evidence was given by increased plankton biomass and single species dominance in production sites. However, these findings can not solely be ascribed to the introduction of aquaculture as various other factors may also contribute to the water quality of these ecosystems.

This thesis studies the role accounting plays in the monitoring and reporting of soil quality in one sector of the agricultural industry, broadacre farming. A survey was conducted with broadacre farmers in the Loddon Catchment, Victoria, Australia. The primary aim was to determine the effectiveness accounting plays in providing information to decision makers relative to the productive capacity in soil quality and not just on profits. The capital asset in this study was defined as soil quality. Soils and soil quality in particular, are major elements in determining land value. The concern is decisions are being made by potential buyers and other decision makers, particularly policy makers, with regards to soil quality on the basis of incomplete and often misleading information. It is proposed that a major reason is due to the fact that different participants in the agricultural and accounting industries require and use different information. The accounting systems used by farmers are those that have been developed for the manufacturing sector which may not be appropriate for managing long-term, complex resources such as soil. The farmers themselves did not find formal accounting reports useful for decision making because these reports are based on uniform standards and market prices. The topic of soil quality and land degradation is viewed from two perspectives. In one perspective, the proprietary view; the accounting emphasis is on the ownership of assets and the change, both in income and capital, in these assets over time. In this case the accounting equation is seen as assets - liabilities = equities. The proprietor takes all the risk. A more recent perspective in accounting, the entity view, emphasises the assets whether financed from equity or debt and where the accounting equation is seen as assets = equities. The emphasis changes to the income flow from these assets and more interest is shown in current market prices as a reflection of the future value of these assets Profit is not necessarily a good indicator of what farmers are doing for their capital asset. There needs to be greater emphasis on costs undertaken for the conservation of soil. Those costs should be considered an investment and put into the balance sheet and not the profit and loss statement. The major finding of study demonstrates that decision making groups have different

Wong Chi Hang Francis.
"Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2000-2001, design report."
On double leaves.
Chapter 1.0 --- INTRODUCTION
Chapter 1.1 --- Genesis
Chapter 1.2 --- Initial association
Chapter 1.3 --- Definition of main issue
Chapter 1.4 --- Site selection
Chapter 2.0 --- ANALYSIS
Chapter 2.1 --- Historical analysis
Chapter 2.2 --- Intricate meanings of 'Hill' to present people
Chapter 2.3 --- Comparative analysis of small hill and commercial hill
Chapter 3.0 --- CONCEPTION
Chapter 3.1 --- Project value
Chapter 3.2 --- Objective and new role of hill
Chapter 3.3 --- Definition of planning issue
Chapter 4.0 --- EXPLORATION
Chapter 4.1 --- Analogy of principle of clinical microbiology with the urban-hill phenomenon
Chapter 4.2 --- "Intrinsic quality of hill as journey, height or out look"
Chapter 4.3 --- Reading what 'Hill' is
Chapter 5.0 --- DEVELOPMENT
Chapter 5.1 --- Meaning of issue
Chapter 5.2 --- Thesis argument
Chapter 5.3 --- Programmatic mean
Chapter 5.4 --- Client profile
Chapter 5.5 --- Users profile
Chapter 5.6 --- Schedule of accommodation
Chapter 6.0 --- FINAL DESIGN
Chapter 6.1 --- Planning Strategy
Chapter 6.2 --- Site plan design
Chapter 6.3 --- Architectural design

Modern pig farming production may over burden the environment with organic substances, exposure of bacterial pathogens and introduction of resistance gene. This may be caused by the pig’s droppings, lack of seepage management or accidental spillage of seepage which may impact on the environment and its physicochemical parameters. The objective of this study is to determine and assess the level of bacteriological pollution emanating from the pig farm and their impact on the physicochemical parameters of soil and water as well as to identify the presence of antibiotic resistance gene of these prevailing bacteria. Soil and water samples were collected monthly for a period of six months (March- August 2013). Samples were collected at pig enclosures, soil 20 m and 100 m away from pig enclosures, constructed wetland used for treating pig farm wastewater, soil 20m and 100 m away from constructed wetland. Procedure followed for analysing soil and water samples includes physicochemical analyses, viable cell counts of 10-1 to 10-8 dilutions, identification of bacteria using API 20E test kit, antibiotic susceptibility analyses, and identification of resistance gene using molecular procedures. The media that were used for viable cell counts were, Nutrient agar, MacConkey Agar, Xylose Lysine Deoxycholate agar (XLD agar), and Eosin Methylene Blue (EMB). Physicochemical parameters of water showed unacceptable high levels of analysed parameters for BOD (163 mg/L to 3350 mg/L), TDS (0.77 g/L to 6.48 mg/L), COD (210 mg/L to 9400 mg/L), NO3 (55 mg/L to 1680 mg/L), NO2 (37.5 mg/L to 2730 mg/L), and PO43− (50 mg/L to 1427 mg/L) were higher than the maximum permissible limits set by Department of Water Affairs and Forestry (DWAF). For soil samples TDS (0.01g/L to 0.88 g/L), COD (40 mg/L to 304 mg/L), NO3 (32.5 mg/L to 475 mg/L), and NO2 (7.35 mg/L to 255 mg/L) and PO43- (32.5 mg/L to 475 mg/L ) were observed to be higher than recommended limits set by Federal Ministry for the Environmental (FME). The viable cells in soil samples 30cm depth ranged from 0 cfu/mL to 2.44 x 1010cfu/mL, in soil 5cm depth ranged from 1.00 x 101 cfu/mL to 1.91 x 1010 cfu/mL, and in water samples viable cells ranged from 5.00 x 101 to 5.05 x 109. Pseudomonas luteola (Ps. luteola), Escherichia vulneris (E. vulneris), Salmonella choleraesuis spp arizonae, Escherichia coli 1(E. coli 1), Enterobacter cloacae, Pseudomonas flourescens/putida (Ps. flourescens/putida), Enterobacter aerogenes, Serratia ordoriferal, Pasteurella pneumotropica, Ochrobactrum antropi, Proteus vulgaris group, Proteus vulgaris, Salmonella spp, Aeromonas Hydrophila/caviae/sobria1, Proteus Mirabillis, Vibrio fluvials, Rahnella aquatillis, Pseudomonas aeruginosa (Ps. aeruginosa), Burkholderia Cepacia, Stenotrophomonas maltophilia (St. maltophilia), Shwenella putrefaciens, Klebsiela pneumonia, Cedecea davisa, Serratia liquefaciens, Serratia plymuthica, Enterobacter sakaziki, Citrobacter braakii, Enterobacter amnigenus 2, Yersinia pestis, Serratia ficaria, Enterobacter gergoriae, Enterobacter amnigenus 1, Serratia marcescens, Raoutella terrigena, Hafnia alvei 1, Providencia rettgeri, and Pantoa were isolated from soil and water samples from the pig farm. Isolates were highly resistant to Penicillin G, Sulphamethaxazole, Vancomycin, Tilmocozin, Oxytetracycline, Spectinomycin, Lincomycin, and Trimethoprim. The most resistance genes detected in most isolates were aa (6’)-le-aph (2”)-la, aph (2”)-lb, aph (3”)-llla, Van A, Van B, Otr A and Otr B. Pig farm seepage is causing bacterial pollution which is impacting negatively on the natural environment in the vicinity of pig farm by introducing bacterial pathogens that have an antibiotic resistance gene and is increasing the physicochemical parameters for soil and water in the natural environment at the pig farm. It is therefore recommended that pig farms should consider the need to implement appropriate regulatory agencies that may include the regular monitoring of the qualities of final effluents from waste water treatment facilities. In addition there is a need to limit soil pollution in order to safe guard the natural environment in the vicinity of pig farm from bacteriological pollution and introduction of antibiotic resistance gene. It is also recommended that more advanced technologies should be introduced that will assist pig farms to manages the seepage properly.
Environmental Sciences
M. Sc. (Environmental Sciences)

This study focused on the impact of climate change and adaptation on small-scale cattle and sheep farming in the Eastern Cape province of South Africa. Using information from 500 livestock farmers between 2005 and 2009 farming season, three methods of analysis were used to determine impacts of climate change and adaptation. They were Principal Component Analysis (PCA), Binary Logistic Regression Model (BLRM) and Heckman Probit Model (HPM). Findings revealed that cattle production decreased during the study period 2005 to 2009. Preliminary descriptive statistics results indicated that farmers had different perceptions on climate change and adaptation measures between the periods 2005 and 2009. Further analysis using PCA showed that the different perceptions could be grouped into: (i) drought and windy weather patterns; (ii) information and adaptation; (iii) climate change extension services; (iv) intensive cattle and sheep production; and (v) temperatures. The results of the BLRM indicated that the most significant factors that affected climate change and adaptation were: (i) non-farm income per annum; (ii) type of weather perceived from 2005 to 2009; (iii) livestock production and ownership; (iv) distance to weather stations; (v) distance to input markets; (vi) adaptation strategies and (vii) annual average temperature. From the HPM the results indicated that marital status, level of education, formal extension, temperatures and the way in which land was acquired, significantly affected awareness on climate change. Variables that significantly affected adaptation selections were gender, formal extension, information received on climate change, temperatures and the way in which land was acquired.It was concluded that in the area of study, change in climate was already perceived by small-scale cattle and sheep farmers. Households that perceived differences in seasonal temperatures during the survey period were less likely to adapt to climate change. Having access to extension services increased the likelihood of adaptation to climate change. Information on climate change to improve livestock production appeared to play a significant role in the selection of adaptation measures. The recommendation was that government should consider cattle and sheep farmers’ perceptions on climate change when deciding on programmes for cattle and sheep production. It further suggested that the most significant factors that affected climate change, adaptation, and awareness and adaptation selections be considered when adaptation programmes are planned.
Agriculture Animal Health and Human Ecology
D.Phil. (Environmental Management)

There is growing evidence that the way that the world produces and consumes food needs to change. There is growing public awareness of serious environmental threats (e.g. global warming, loss of biodiversity and pollution) as well as social concerns (e.g. poverty, inequality and food security). It is necessary for global agriculture to rethink its approach to food production and to find new ways of producing food that can meet the demands of the growing world population and at the same time reduce the environmental degradation caused by farming. So called green revolution technologies, resulting in high intensity, high input agriculture are damaging the very resources on which agriculture depends; soil and water. Research reveals current conventional practices to be unsustainable. There is a growing recognition, arising from the creation of new knowledge and the development of deeper understanding, that this change is necessary and urgent. Organic (or ecological) farming has emerged as a more beneficial way of producing food from a social and environmental perspective. Demand for, and production of, organic food grew steadily in the second half of the twentieth century and has increased dramatically in the twenty first century. This can largely be ascribed to social learning processes. This growth is not yet reflected in South African agriculture. Given the advantages of organic agriculture, it is necessary to consider how to accelerate its expansion. Understanding the social learning processes of organic farmers and using learning histories are useful tools to create a better understanding of how this can be achieved. The objective of this dissertation is to make use of four social learning frameworks to enhance the understanding of the social learning dynamic of organic farmers by: • Using existing baseline data from a survey of the organic farming sector to draw out the learning histories. • Developing an understanding of four social learning frameworks. • Combining the learning histories and the understanding of social learning frameworks to form a deeper understanding of the social learning dynamics in the South African organic agricultural sector. A literature review of the organic sector and of four learning frameworks (profound change, conversion of knowledge, deeper learning, and the pedagogy of adult social learning) is used to develop an understanding of the essence of organic agriculture and how people learn. Information from a survey of organic farmers in South Africa, is used to impregnate the learning frameworks in order to develop an understanding of how organic farmers in South Africa are learning Open-ended questions from the survey are analysed and interpreted based on the understanding of learning frameworks. Selected statements that reflect social learning are highlighted, incorporated into the learning frameworks and discussed to better understand how organic farmers are learning. The analysis indicates that a high proportion of organic farmers are social learners. The four frameworks demonstrate that many organic farmers see their role as more than just providers of food. They also see themselves as custodians of the land with a deep concern for the environment. Fewer organic farmers demonstrate an understanding of social issues. Those that did showed a clear understanding of the need to integrate social considerations into food production. Networking and sharing of learning are important methods of knowledge creation among organic farmers as a result of the limited research and support for organic farmers in South Africa. Recommendations to accelerate and understand the learning by organic farmers and consumers are provided. Future research is suggested in order to investigate how to assist organic and conventional farmers to better understand learning, identify how learning can be enhanced or retarded, and actively engage in learning that facilitates knowledge creation.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Pasture-based dairy farming is the major land use in the Tsitsikamma region of the Eastern Cape. Permanent kikuyu grass (Pennisetum clandestinum) dominates pastures in the region. Kikuyu pastures do not, however, provide adequate year-round quality feed for dairy cows. This has led to the use of annually sown pastures with perennial ryegrass (Lolium perenne) to provide winter forage. Soil degradation under this management has, however, become recognised as a major limitation. Soil quality and degradation under annual and permanent pasture in the region were evaluated in three separate studies. These were (i) an investigation of the extent of loss of soil organic matter and related soil microbial properties and aggregate stability under annual pastures, (ii) a comparison of soil physical properties under annual and permanent pastures and (iii) a survey of the nutrient status of soils and pasture herbage in the region. In the first study, four commercial dairy farms, situated on sites which represented the three main soil groups in the region were sampled, were taken from under permanent kikuyu pastures, annual ryegrass pastures and undisturbed native vegetation nearby. In comparison with undisturbed, native vegetation, soils under both annually cultivated and permanent pasture had gained soil organic matter on the sandy, low rainfall eastern end of the Tsitsikamma. By contrast, at the higher rainfall, finer-textured, western end, where the native vegetation consists of coastal forest, there was a loss of soil organic matter under both types of pasture. Despite this, soil organic C content was lower under annual ryegrass than permanent kikuyu pasture at all the sites reflecting the degrading effect of annual cultivation on soil organic matter. As a consequence, labile, K(2)S0(4) - extractable C, microbial biomass C, basal respiration, arginine ammonification, flourescein diacetate hydrolysis rates and aggregate stability were all less under annual ryegrass than permanent kikuyu pastures at all the sites. The effects of annual ryegrass and permanent kikuyu pastures on soil physical properties and root length density were compared with those of undisturbed native vegetation on the four experimental sites. Root density and the depth of rooting were much less under annual ryegrass than under kikuyu pastures or native vegetation. There was no consistent effect of improved pastures or pasture type on bulk density and total porosity or penetrometer resistance, although annual pasture soils generally had higher bulk densities and lower total porosities than those under native vegetation. There was a tendency for smaller saturated hydraulic conductivity and air permeability under ryegrass than kikuyu pastures, regardless of whether total porosity was higher or lower under ryegrass. This was attributed to annual cultivation and subsequent natural consolidation causing a decrease in pore continuity under ryegrass pastures. Penetrometer resistance values confirmed the presence of subsoil compacted layers at two annual ryegrass pasture sites. At one such site, subsoil tillage was effective in reducing penetrometer resistance and bulk density, increasing pore continuity (as evaluated by hydraulic conductivity and air permeability) and greatly increasing root density and rooting depth. The nutrient status of soil and herbage from annual ryegrass and permanent kikuyu pastures sampled from 40 dairy farms in the Tsitsikamma region were evaluated. Along with the decreased organic matter content, there was a decrease in soil pH and a loss of exchangeable cations under annual pastures. Large concentrations of extractable P and sometimes exchangeable K were measured in soils under both ryegrass and kikuyu pastures and it was concluded that the rates of applied P, and sometimes K, were often excessive (particularly under kikuyu). Various nutritional problems were also identified. These included the need for Ca supplementation, particularly under kikuyu, due to the low herbage Ca concentrations. The low Ca : P ratio measured in annual ryegrass pastures, and more particularly in kikuyu herbage, highlighted the low Ca content of herbage and also the tendency of kikuyu grass to accumulate large concentrations of P. The large K concentrations and high K : Ca +Mg ratios identified in pasture herbage suggest the potential for animal nutritional problems such as hypomagnesaemia. It was concluded that although kikuyu is an excellent pasture in terms of dry matter production it tends to be deficient in Ca (and sometimes Na) and can contain prohibitively high K levels, which are likely to induce Mg deficiencies in grazing animals. The micronutrient concentrations in herbage were generally adequate, although copper concentrations tended to be low suggesting that fertilizer applications and/or feed supplementation is required. It was concluded that annual conventional tillage results in a substantial loss of soil organic matter, soil microbial activity and aggregate stability under annual ryegrass pastures when compared to those under permanent kikuyu grass. This loss of soil organic matter can result in natural consolidation of the soil in the cultivated layer and exasperated through treading by the grazing cows. The annual cultivation can also lead to the formation of a subsoil compacted layer. Nonetheless, compaction can also occur under permanent pasture presumably due to treading damage. Careful management to avoid treading damage to pastures should be practised. In order to protect the organic matter status of annual pastures, direct drilling of such pastures should be seriously considered. In some cases, annual fertilizer P rates (and to lesser extent those of K) could be reduced considerably since the levels accumulated in the soils are excessive.
Thesis (M.Sc.Agric.)-University of Natal, Pietermaritzburg, 2002.

It is claimed that high returns can be achieved from hunting and ecotourism operations. As a result wildlife production is a rapidly growing form of land-use in South Africa. Lately, rural African communities have approached regional conservation agencies for aid to establish small game reserves so that they too may benefit from wildlife production. However wildlife operations have high input costs relative to domestic stock operations and no attempt has been made to determine the effect of property size on the costs and revenue generated by wildlife. It is thus necessary to conduct a Cost-Benefits Analysis to ascertain this effect by determining the opportunity cost incurred by choosing wildlife over other land-uses suitable in semi-arid savannas, namely communal subsistence production and commercial beef production. This project attempts to quantify the revenue generated, and the variable costs and fixed costs incurred by wildlife production, subsistence production and commercial beef production in order to observe their behaviour against property size and by this means to establish the size ranges for which each of the three land-uses is most appropriate. Mathematical modelling is used to define each of the three land-uses and how their revenue and cost curves interact with property size. The resultant profit curves are able to assess only the financial benefits from each of the land-uses to the local community. An assessment of the full economic benefits to the local and broader community would require different criteria and apportionment of costs and revenue. The effect of property size on fixed costs is the single most important factor which distinguishes the behaviour of the profit curves of the three land-use options: subsistence production has negligible fixed cost input and so is able to achieve greater profitability than either beef or wildlife at small property sizes. Beef has high input costs per hectare at small land sizes which diminish with each unit of additional land. Wildlife operations also have high input costs at small land-sizes which decrease per hectare with additional land added. However due to the service industry nature of wild life operations, fixed costs increase per hectare after some point (in this case it is assumed to be 2000 ha). This is because the attractiveness of game reserves to tourists increases with size due to the inclusion of "many" species of game, which in turn increases the number of people entering the park per hectare and as such the fixed cost input required to accommodate those extra people. The specific results derived from the model indicate that the profit curve of wildlife rises far more steeply than those of either subsistence production or commercial beef production. However, due to the effect of input costs, both commercial beef and subsistence production are more profitable at land sizes of less than 3000 ha. This indicates that investing large sums of money into small game reserves of less than 3000 ha may not be justified on the basis of profits alone.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

This study explores the perceptions of the value of community gardens by members and the relationship between this activity and homestead farming activities in Ogagwini, Umbumbulu District, KwaZulu-Natal. Establishing and supporting community gardens is consistent with the strategies adopted by South African national and provincial government to alleviate poverty, address food security and improve livelihoods for rural people. However, there is a lack of literature available on why rural people choose to involve themselves in community garden projects and whether these reasons are those intended by policy makers. There is abundant research on community gardening – most of it either urban or not specific as to setting. This literature is useful for the generic information it provides, but does not provide the scope of understanding that is unique to rural community gardening in South Africa. Thus this study contributes to understanding rural community gardens and possible adjustments needed by extension workers and development strategies to ensure effective food gardening practices in rural KwaZulu-Natal. The first extension facilitated community garden activities in Ogagwini were established in 1993 with the support of the provincial DAEA. Some community garden members are also members of the Ezemvelo Farmers Organisation (EFO), a group of farmers engaged in commercial small-scale farming. This research attempted to find out how community gardening activities were related to small-scale commercial homestead activities. Specifically, the study sought to investigate issues such as preferences among farmers between community gardens and homestead farming; the social and economic benefits derived from community gardens; and perceptions around environmental/ecological issues surrounding community gardens and homestead farming. A survey questionnaire on community garden activities and perceptions was given to EFO members and used to identify participants for this study. Committee members of the EFO (also members of community gardens) arranged for five gardens to be investigated. In-depth data was collected at the actual garden sites using semi-structured focus group discussions and participant observation. The data from the survey questionnaire was verified and clarified by semi structured probing during these discussions. A spiral approach was used to organise responses and make sense of the data within social, economic, and environmental themes. After three garden visits, no new knowledge was forthcoming and due to time constraints the study was limited to these three groups. The study found that there were no distinct linkages between homestead farms and community gardens, but that the systems operated on different principles. Community gardens were used to produce cabbages, carrots, beetroot, onions, green peppers and spinach mainly for consumption, whereas homestead farms produce field crops such as maize, amadumbes (taro), sweet potato, potatoes, pumpkins and peanuts. The study further identified social and economic benefits and environmental impacts and reinforces the importance of knowledge sharing amongst participants. The main benefits identified were income generation, sharing of knowledge and technical support The Department of Agriculture should carefully address sustainability issues when planning and implementing community gardens. This would include being able to carry on in the absence of an agricultural extension officer. Training programmes need to ensure that learning is transferable; that it is not overly commodity or technology specific and includes promotion of environmental awareness. This study has highlighted a number of potentially valuable issues for further situated research in the area of farming protocols, markets and the social value of community gardening within rural communities.

Although conventional or scientific farming practices have been encouraged and promoted by state and other agencies, rural and resource poorfarmers have increasingly resorted to indigenous farming practices. This study was undertaken to test the hypothesis that indigenous farming practices are not only environmentalfriendly, but are more profitable than conventional practices. A conceptual framework for testing the hypothesis was formulated based on a comparison of Margins above Specified Cost of indigenous and conventional farming practices. The data required were identified and a methodology for data collection and analysis was designed. The research methodology included a literature review, a GIS based sample scheme designedfor data collection and statistical analysis. As a major feature of this component of the mini-dissertation, the literature review reveals that indigenous farming practices have positive impact on the environment by improving soil through mulching, composting and use of non-toxic control ofpests and diseases. On the other hand the review reveals that conventional practices can impact negatively on the environment.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

New Zealand, having large areas of hilly landscapes, is subject to the risk of soil erosion, and summer and autumn droughts that limit pasture growth, which in turn affects the livestock-based economy. The nitrogen and phosphorus input in fertilisers coupled with livestock excreta and soil disturbance impose a serious threat to downstream water quality. The planting of trees is one option used to decrease soil erosion, increase the quantity of forage and manage runoff. To date, research has mainly focused on wide spaced poplar trees for feed quality and their effects on understorey pasture growth. However, there is increasing interest in the use of densely planted willow and poplar for fodder purpose. The effects of young (< 5 yrs old) willow and poplar planted at close spacing on runoff, soil erosion, growth of understory pasture and nutrient losses have never been studied in New Zealand. Three field trials (two at Crop and Research Unit, Moginie, Manawatu and one at Riverside Farm, Masterton) were conducted between October 2004 and November 2006 that incorporated comparative establishment and growth of densely planted willow and poplar and their effects on soil moisture, runoff, sediment load and nutrient losses from grazed and fertilised farmland. It was concluded that densely planted willow and poplar (3-4 yrs) reduced total nitrogen (TN) and dissolved reactive phosphorus (DRP) by 47 % each and sediment load by 52 %. Young trees reduced surface runoff and soil moisture more as they aged. However, due to their deciduous nature willow and poplar were not effective in reducing surface runoff in winter and early spring. Sheep preferred camping under trees, especially in late spring and summer, and this led to greater deposition of dung and urine under trees than open pasture. Sheep grazing, especially in winter, significantly increased sediment and nutrient loads in runoff water. The N and P fertiliser application increased nutrient load in runoff water well above the threshold level required to initiate algal growth to create eutrophication. Densely planted willow and poplar significantly reduced understorey pasture growth by 23 % and 9 %, respectively, in their second year at Moginie, mainly due to shade, but coupled with soil moisture deficit in summer. The pasture growth in a willow browse block was 52 % of that in open pasture as a result of shade and differences in pasture species composition. Sheep browsing reduced willow leaf area significantly. Willow and poplar survival rates were similar (P > 0.05) after two years of establishment (100 % vs 90.5 %, respectively). However, willow grew faster than poplar in height (1.90 vs 1.35 m), stem diameter (43.5 vs 32.6 mm), canopy diameter (69 vs 34 cm) and number of shoots (8.7 vs 2.3) at the age of two years, respectively. The research clearly demonstrated that densely planted young willow and poplar trees can reduce runoff, sediment load and nutrient losses from farmland to freshwater, but shade and soil moisture can limit pasture growth under trees. It is recommended that willow and poplar should be planted at wide spacing on the whole farm to minimise loss of pasture. Where blocks of trees are necessary, such as willow browse blocks, sheep browsing can be used as a tool to reduce shade to improve pasture growth. Livestock access to riparian strips should be minimal to avoid livestock camping that can have deleterious effects on water quality.

Agricultural greenhouse gas emissions within New Zealand account for 48 percent of all national greenhouse gas emissions. With the introduction of the emissions trading scheme farmers will soon be liable for their emissions, introducing additional physical constraints and financial costs. Farmers that still operate within the sector will have two options to meet emissions targets; to purchase carbon credits from the open market, or mitigate farm level emissions at added costs to the farmer. This study examines the latter case of assessing farm level options for mitigating greenhouse gas emissions, and quantifying the physical and financial costs associated with mitigation strategies. Results show that, based on the assumptions in the study, there are available options for dairy farmers to profitably meet Kyoto protocol emissions targets. Sheep and beef farmers can increase profit, but cannot meet Kyoto protocol emissions targets, through examined scenarios.

M.Tech. (Architectural Technology)
This thesis deals with the reappropriation of an existing parking garage into a language institute at Constitution Hill. Through the generation of a flu id conversation between architecture and people this thesis aims to address the underlying social miscommunication present within South African society through a socially motivated architectural manifestation. The underlining aim of this thesis will be the generation of a socially orientated architectural platform that allows and encourages cross-pollination. This architectural platform will revolve around and investigate the many opportunities that language offers asa social mediator and how these opportunities can aid in the democratization of identity generation. This new approach will be more representative of the complex multicultural society that is present within South Africa and as a result will end up being more democratic in nature.

The generation of large quantities of mine wastewater in South African coal mines and the needs for a cost effective, as well as an environmentally sustainable manner of mine water disposal, have fostered interests in the possibility of utilizing mine water for irrigation. Such a possibility will not only provide a cost-effective method of minimizing excess mine drainage, as treatment using physical, chemical and biological methods can be prohibitively expensive, but will also stabilize the dry-land crop production by enhancing dry season farming. Considering the arid to semi-arid climate of South Africa, the utilization of mine water for irrigation will also boost the beneficial exploitation of the available water resources and relieve the increasing pressure on, and the competition for, dwindling amounts of good quality water by the various sectors of the economy. The disposal of excess gypsiferous mine water through irrigation has been researched in a few collieries in the Witbank area. In this study, the assessment of the impacts of using gypsiferous mine water for irrigation were carried out in parts of the Upper Olifants basin upstream of Witbank Dam, using the ACRU2000 model and its salinity module known as ACRUSalinity. The study area was chosen on the bases of locations of previous field trials and the availability of mine water for large-scale irrigation. The primary objectives of the study were the development of relevant modules in ACRU2000 and ACRUSalinity to enable appropriate modelling and assessment of the impact of large-scale irrigation with mine water and the application of the modified models to the chosen study area. The methodology of the study included the modifications of ACRU2000 and ACRUSalinity and their application at three scales of study, viz. centre pivot, catchment and mine scales. The soils, hydrologic and salt distribution response units obtained from the centre pivot scale study were employed as inputs into the catchment scale study. The soils, hydrologic and salt distribution response units obtained from the catchment assessment were in turn applied in similar land segments identified in the mine used for the mine scale study. The modifications carried out included the incorporation of underground reservoirs as representations of underground mine-out areas, multiple water and associated salt load transfers into and out of a surface reservoir, seepages from groundwater into opencast pits, precipitation of salts in irrigated and non-irrigated areas and the incorporation of a soil surface layer into ACRUSalinity to account for the dissolution of salts during rainfall events. Two sites were chosen for the centre pivot scale study. The two sites (Syferfontein pivot of 21 ha, located in Syferfontein Colliery on virgin soils; Tweefontein pivot of 20 ha, located in Kleinkopje Colliery on rehabilitated soils) were equipped with centre pivots (which irrigated agricultural crops with mine water), as well as with rainfall, irrigation water and soil water monitoring equipment. The pivots were contoured and waterways constructed so that the runoff could leave the pivots over a weir (at Tweefontein pivot) or flume (at Syferfontein pivot) where the automatic monitoring of the quantity and quality of runoff were carried out. The runoff quantities and qualities from the pivots were used for verification of the modified ACRU2000 and ACRUSalinity. The catchment scale study was on the Tweefontein Pan catchment, which was a virgin area mainly within the Kleinkopje Colliery, draining into the Tweefontein Pan. The data on the water storage and qualities in Tweefontein Pan, as well as the soil water salinities in the irrigated area located within the catchment were used for verification of results. In the catchment scale study, different scenarios, including widespread irrigation on virgin and rehabilitated soils, were simulated and evaluated. For the mine scale study, the Kleinkopje Colliery was used. The colliery was delineated into 29 land segment areas and categorized into seven land use types, on the basis of the vegetation and land uses identified in different parts of colliery. The centre pivot and catchment scale studies indicated that the impacts of irrigation with low quality mine water on the water resources are dependent on the soil types, climate, the characteristics and the amount of the irrigation mine water applied, whether irrigation was on virgin on rehabilitated soils and the status of the mine in terms of whether a regional water table has been re-established in an opencast mining system or not. The studies further indicated that the irrigation of agricultural crops with low quality mine water may lead to increases in soil water salinity and drainage to groundwater, but that the mine water use for irrigation iii purposes can be successfully carried out as most of the water input onto the irrigated area will be lost through total evaporation and a significant proportion of the salt input, both from rainfall and irrigation water, will either be precipitated in the soil horizons or dissolved in the soil water of the soil horizons. By irrigating with a saline mine water therefore, the salts associated with the low quality mine water can be removed from the water system, thereby reducing the possibility of off-site salt export and environmental pollution. On-site salt precipitation, however, may lead to accumulation of salts in the soil horizons and consequent restriction of crop yields. Therefore, efficient cropping practices, such as leaching and selection of tolerant crops to the expected soil salinity, may be required in order to avoid the impact of long-term salinity build up and loss of crop yields. The simulated mean annual runoff and salt load contribution to Witbank Dam from the Kleinkopje Colliery were 2.0 x 103 MI and 392 tons respectively. The mean annual runoff and salt load represented 2.7% and 1.4% of the average water and salt load storage in Witbank Dam respectively. About 45% of the total water inflow and 65% of the total salt load contribution from the study area into Witbank Dam resulted from groundwater storage. From the scenario simulations, the least salt export would occur when widespread irrigation is carried out in rehabilitated areas prior to the re-establishment of the water table due to a lower runoff and runoff salt load. It may therefore be a better water management strategy in active collieries if irrigation with mine water is carried out on rehabilitated soils. In conclusion, this research work has shown that successful irrigation of some (salt tolerance) crops with low quality mine water can be done, although increases in the soil water salinity of the irrigated area, runoff from the irrigated area and drainage to the groundwater store can occur. Through the modifications carried out in the ACRU2000 model and the ACRUSalinity module in this research work, a tool has been developed, not only for application in the integrated assessment of impact of irrigation with mine water on water resources, but also for the integrated assessment and management of water resources in coal-mining environments in South Africa.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

This study’s main goal was to evaluate Bacillus subtilis inoculation and mine water irrigation effect on germination, growth, nodulation, physiology and shoot/grain quality of cowpea genotypes exposed to extreme climatic conditions (elevated temperatures). The first experiment evaluated the interactive effect of Bacillus subtilis (BD233) inoculation and elevated temperature on germination indices and plumule lengths of three genotypes (Asetanapa, Soronko and Nyira) of cowpea. The results showed that interaction between B. subtilis (BD233) and temperature significantly (p<0.05) influenced the germination indices (germination percentage (G%), germination index (GI) and germination rate index (GRI)) and plumule length of cowpea seedlings and genotype responses were significantly different. At elevated temperature (35oC), inoculation with B. subtilis (BD233) enhanced seed germination and growth of cowpea. The second experiment evaluated the effect of temperature on growth and nutritional content of cowpea incubated for seven days in a growth chamber. The results showed that when cowpea genotype, Soronko, was incubated at different temperature regimes, the whole plant biomass, shoot carbon and crude protein contents were significantly affected with temperature increases at all three stages of the plants’ life cycle. The results suggest that the pre-flowering (40 DAP) and flowering (90 DAP) stages of cowpea compared to post-flowering (123 DAP) are more susceptible to elevated temperatures (30-35oC). The third experiment evaluated Bacillus subtilis inoculation and mine water irrigation effect on growth, nodulation, physiology and nutritional content of cowpea under glasshouse conditions. The results revealed that the interaction of B. subtilis (BD233) inoculation and mine water (75% AMD) irrigation was significant for the growth, nodulation, stomatal conductance, chlorophyll contents and shoot/grain nutritional quality of cowpea genotypes. In comparison with control, generally, B. subtilis inoculation enhanced the growth, nodulation and yield of all tested cowpea genotypes and irrigation with mine water significantly influenced the mineral contents in both shoot and grain of cowpea. Taken together, findings in this study have implications for cultivation of cowpea, an important candidate for food/nutrition security in Africa, under future climate change scenarios.
Environmental Sciences
M. Sc. (Environmental Sciences)

Landscape heterogeneity is thought to differ among farm management types (i.e. organic and conventional), and this difference is hypothesized to result in variations in pest control by natural enemies. However, it is unclear if these variations in pest control are driven by landscape structure or by farm management practices themselves. Remotely sensed datasets were used to describe the landscape structure surrounding a group of organic and conventional caneberry farms in Oregon and Washington that have different leafroller parasitism rates attributed to farm management type. A finer scale survey was done at one of the farms using the remotely sensed data as well as field surveys. Landscape metrics of diversity, richness and percent non-crop were used to describe the landscapes surrounding the farm fields at scales ranging from 0.05 km to 5.00 km for the large scale study, and 0.05 km to 0.20 km for the fine scale study. In the fine scale study, data on parasitoid species assemblages, diversity, and parasitism rate were collected and analyzed against the calculated landscape metrics spatially and seasonally. The purpose of this study was to quantify effects of farm management type on habitat structure, effect of habitat structure on leafroller parasitism rate, and to access correlations between landscape metrics calculated at the landscape and field scale. Overall, the farms were embedded in a landscape that was broadly similar, with very few differences in landscape structure occurring between organic and conventional farms. Organic farms had higher vegetation height class diversity at the largest scale compared to conventional farms, while conventional farms had significantly higher percent non-crop area compared to organic farms. There was no significant effect of any of the calculated landscape metrics on parasitism rates. In the field scale study, no correlations were found between habitat metrics and parasitism rates, or between field based metrics and those calculated at the landscape scale. The results of this study suggest that conventional and organic caneberry farms in the Willamette Valley are broadly similar in the habitat conditions they provide parasitoids. This suggests that management changes to pesticide use alone could increase levels of leafroller biological control on conventional farms to levels that are comparable to those seen on organic farms. Our comparisons of the landscape scale and field scale landscape metrics showed no connection, this suggests that direct comparisons cannot be made with these particular metrics at these very different scales. Rather than comparing these types of data, it may be more useful to combine them in order to increase the resolution and predictive power of remotely sensed data for describing landscapes at broad scales.
Graduation date: 2013