The current interest in conservation agriculture (CA) technologies is a result of the need to reduce excessive land degradation in most crop producing areas as well as to enhance sustainable food production. Cover crops that are usually grown under CA to provide soil cover, may offer secondary benefits, depending on the farming system. The concept of growing cover crops is a relatively new phenomenon to smallholder farmers. Production of large biomass yields and weed suppression from cover crops were major challenges affecting success and uptake of CA technologies by smallholder irrigation farmers. Coupled with this, low soil fertility limit maize productivity and reduce water use efficiency on smallholder irrigation schemes in what is largely a water strained agro-ecology in South Africa. While cover cropping can increase maize productivity, benefits of different types of mulch are not well understood, leading to challenges in selecting the most appropriate cover crop species to grow in the Eastern Cape Province (EC) of South Africa (SA) which has a warm temperate climate. With respect to any new technology, smallholder farmers are more interested in the economic benefits. Cover crops have been defined as leguminous or non-leguminous plants used for ground cover in various temporal and special configurations used in crop or animal production systems. The purpose of these cover crops is to improve on or more of the following: soil erosion, availability and cycling of N, P, K, Ca and other nutrients, soil moisture and water infiltration, and weed or pest control (Eilitta et al., 2004).. Improvement of animal or human diet may be additional goals. This definition accommodates diverse systems which may include intercrop and sole-cropping systems. In the Eastern Cape Province of South Africa, a government initiative has promoted the growing of winter cover crops in smallholder irrigation schemes (Allwood, 2006). In other parts of Africa, legume food crops have been simultaneously grown with cereal staples to improve both soil cover and human diet (Eilitta et al., 2004). Winter experiments were undertaken in 2007 and 2008 to evaluate biomass accumulation, C and N uptake, weed suppression and response to fertilization. Winter cover crops planted included; oats (Avena sativa), grazing vetch (Vicia dasycarpa), faba bean (Vicia faba), forage peas (Pisum sativum) and lupin (Lupinus angustifolius). After cover crops were terminated, the effects of residues on weeds, fertility, moisture conservation and maize productivity were undertaken in the 2007/08 and 2008/09 summer seasons. Field studies were also done in the 2007/08 and 2008/09 summer seasons to investigate effects of strip intercropping patterns (3:2; 4:2; and 6:2 patterns) of maize (cv. PAN 6479) with mucuna (Mucuna pruriens) or sunnhemp (Crotalaria juncea) on maize productivity and summer cover crop biomass production. In a separate experiment effects of relay intercropping sunnhemp, mucuna and sorghum (Sorghum bicolor) on biomass accumulation and maize productivity were investigated. Decomposition, N and P release from both winter cover crops and summer cover crops were also assessed in laboratory incubation experiments. Oats, grazing vetch and forage peas cover crops produced mean dry mass of 13873 kg/ha, 8945.5 kg/ha and 11073 kg/ha, respectively, while lupin had the lowest dry mass of 1226 kg/ha over the two seasons. Oats responded to fertilization while, there was little or no response from the other winter cover crops. Oats and grazing vetch also reduced weed density by 90 % and 80 % respectively while lupin only reduced weed density by 23 % in relation to the control plots. Nitrogen uptake was 254 kg N/ha for oats while it was 346 kg N /ha for grazing vetch. In the subsequent summer season, grazing vetch and forage pea residues significantly (P < 0.01) improved soil inorganic N. Oat and grazing vetch residues significantly (P < 0.05) reduced weed dry masss and weed species diversity compared to plots with lupin residues and the control. Lack of maize fertilization tended to reduce maize yields but not for maize grown on grazing vetch residues. From an economic perspective, grazing vetch resulted in the highest returns. Decomposition of winter cover crops was much faster for grazing vetch followed by forage peas and lastly oats. Oats had 40 % ash free dry mass remaining after 124 days while grazing vetch and forage peas had 7 % and 16 % respectively. Maximum net mineralized N and P were greater for grazing vetch (84.8 mg N/kg; 3.6 mg P/kg) compared to forage peas (66.3 mg N/kg; 2.7 mg P/ha) and oats (13.7 mg N/kg; 2.8 mg P/kg). In the strip intercropping trials, sunnhemp achieved the highest biomass yield of 4576 kg/ha in the 3:2 pattern while mucuna achieved 1897 kg/ha for the same strip pattern. The 3:2 strip intercropping pattern slightly depressed yields, however, yield reduction was more pronounced in the first season where water stress was experienced. Growing maize on previous cover crop strips failed to increase maize productivity probably due to weed growth during the fallow reducing mineral N in these strips. Decomposition was faster in sunnhemp leaves and mucuna compared to sunnhemp stems. Sunnhemp stems had about 65 % of ash free dry mass remaining after the end of the experiment at 132 days while just over 10 % of mucuna and sunnhemp leaves still remained. Mucuna mineralized 60 mg N/kg and 3.2 mg P/kg and sunnhemp mineralized 45 mg N/kg and 3.5 mg P/kg. Relay intercropping did not significantly (P > 0.05) affect maize biomass and grain yield. Sorghum experienced the largest drop in biomass when relay-intercropped with maize. Mucuna resulted in the highest N uptake (271 kg N/ha) in sole cropping while sorghum had the lowest (88 kg N/ha). Grazing vetch results in high biomass yields with minimal fertilizer application in a warm-temperate climate. Grazing vetch mulch is also the most cost effective mulch for better early weed control, improving soil mineral N status, water conservation and ultimately enhanced maize productivity in smallholder irrigation maize-based systems. The 3:2 pattern maximizes summer cover crop biomass yields compared to the 6:2 and 4:2 patterns. However, the 3:2 pattern may slightly depress yields in a water stressed environment. Relay intercropping mucuna, sunnhemp and sorghum into a maize crop at 42 days after maize sowing has no effect on maize productivity while cover crop biomass yields are low. Having a long winter fallow period after maize harvesting, a common practice in the study area, reduces the positive impact of legume cover crops on soil mineral N. Results suggest that winter cover crops may result in weed control, soil fertility and maize yield improvement benefits while a long fallow period may cancel-out these benefits for summer cover crops. Grazing vetch is a cost effective cover crop that produces high maize yields with minimal fertilizer input. Maize growing on oat mulch requires more fertilizer application than crops growing on grazing vetch mulch. Conservation agriculture systems in which summer cover crops are grown alongside the maize crop with a long winter fallow period do not produce the intended CA benefits.

Although food insecurity is said to have decreased in South Africa in the past years particularly at the national level, however, at household level a substantial proportion of households remains at risk of food insecurity and are experiencing hunger particularly in the Eastern Cape Province were poverty is rife. Food insecurity in the Eastern Cape Province is attributed to the fact that agriculture, the mainstay of the rural economy is no longer given the value that it should carry, does not help the situation. Despite much research on food (in) security in South Africa, the link between poverty and household food security is not at all clear. This study seeks to fill this gap specifically by looking at the linkages in the main between food security and poverty especially in the community level. Amidst the various programmes and initiatives that are in place in South Africa, there is continual prevalence of food insecurity facing the majority of South African households. The major aim of this study was therefore to examine the impact of one of these programmes, the Zanyokwe irrigation scheme in enhancing food security not only for the farmers but also for the surrounding communities. This study adopted a qualitative approach to research. The study unearthed that even though Zanyokwe irrigation scheme has played an indispensable role in enhancing food security for the smallholder farmers and the community at large challenges such as market challenges, road infrastructural issues, land tenure issues, lack of proper coordination amongst the farmers as well as farmer empowerment are a major limitation to the growth of the irrigation scheme and the farmers. Thus, the study recommended that farmer support services, training, agriculture subsidies, improved infrastructure as well as addressing market related challenges will go a long way in reducing the plight of the Zanyokwe farmers as well as enhancing food security

It is verified in this thesis: to be the nature of capital strength extraction of surplus labor makes borderless. To this end, international competitiveness and efficiency productivist guide the European Common Agricultural Policy evading wealth polo Juazeiro/ Petrolina, in that obtains control of the land, water and all stages of production in the field by imposing stamp certifications as a determinant of the free movement of goods in the European market. Centered in the rules of accumulation and exploitation of the system capital, agro-hydro expands supported and encouraged by the state, as the only way to raise the standard of living of workers in town and country, justified the quantitative employment generated, which in turn, can result in unnecessary consumption of the city. While this discourse is divulgadado, land and water become appropriated by the owners of capital specifically for crop production required by the international market. Thus, demand for tropical fruits by countries that comprise the European Union has allowed the PAC to exert its total domination in the Valley, determining how to behave employee and employer, without necessarily having title to the land. Thus, the irrigation policy in areas that were implanted with the irrigated areas in particular: Bebedouro Nilo Coelho and Salitre has actually expanded production quantitatively and qualitatively, but this apparently positive balance has been extracted from the land rent , materialized in the precarious and temporary employees as well as the monopolization of land of small farmers who still has nominal bond with it. It is therefore the mediation of this land in the center of the factors that promote the separation between the place of production of the means of life that does not take the form of variable capital necessary reproduction of the worker and the place of production and reproduction of capital. With this, the surplus labor time that capital appropriates is shared by many capitalist agents in Polo and Europe. / Comprova-se na presente tese que: por ser a natureza do capital força extratora do trabalho excedente o faz sem fronteiras. Para tanto, a competividade internacional e a eficiência produtivista norteiam a Política Agrícola Comum Europeia a subtrair a riqueza do Polo Juazeiro/Petrolina, na medida em que obtêm o controle da terra, água e todas as etapas da produção no campo, mediante a imposição do selo de certificações como determinante à livre circulação da mercadoria no Mercado Europeu. Centrado nas regras de acumulação e exploração do sistema do capital, o agro-hidronegócio se expande apoiado e incentivado pelo Estado, como sendo a única saída para elevar o nível de vida dos trabalhadores da cidade e campo justificado no quantitativo de emprego gerado que, por sua vez, pode resultar no consumo de produtos supérfluos na cidade. Enquanto esse discurso é propagandeado, a terra e água passam a ser apropriadas pelos proprietários do capital especificamente para produção de cultivos requeridos pelo mercado internacional. Assim, a procura de frutas tropicais pelos países que compõem a União Europeia tem permitido que a PAC exerça seu total domínio no Vale, determinando como deve comportar-se empregador e empregado, sem necessariamente ter o título de propriedade da terra. Desse modo, a politica de irrigação nas áreas em que foram implantados os Perímetros Irrigados, em especial: Bebedouro, Nilo Coelho e Salitre têm de fato ampliado quantitativa e qualitativamente a produção; porém, esse saldo aparentemente positivo tem sido extraído da renda da terra, materializado no trabalho precarizado e temporário dos assalariados, bem como na monopolização da terra dos pequenos produtores que ainda têm vínculo nominal com a mesma. É, portanto, a mediação da renda fundiária que está no centro dos fatores que promovem a separação entre o lugar da produção dos meios de vida que não assumem a forma de capital variável, necessários à reprodução do trabalhador e o lugar de produção e reprodução do capital. Com isso, o excedente do tempo de trabalho de que o capital se apropria é repartido por muitos agentes capitalistas no Polo e na Europa.

MENVSC / Department of Geography and Geo-Information Sciences / Agricultural abandonment is a challenge in areas of South Africa more especially in rural areas. The study employs both qualitative and quantitative methods of in sampling and collection and analysis. It adopted a case cross-sectional study design. This design is a case study in nature, hence this study compared the active and none active farmers in identifying the causes and effects of the phenomenon studied. Comparatively, the study sought to find out if there are factors influencing farm abandonment and its consequences in Tshiombo village. The study was based on field surveys allowing for observation and with respect to agricultural abandonment. In addition to observation open ended questions together with questionnaires were administered to extension officers. The data collected from open ended questions and questionnaires was recorded and subjected to descriptive analysis. Several factors have been identified influencing farm abandonment. The challenges ranges from needs prioritization, infrastructure and capacity. It was recommended that government should reinstate its support to small scale farmers prioritize the maintenance of irrigation canals. The prioritisation of agriculture will attract many into agricultural practice with the aim of reducing poverty and starvation in rural communities. / NRF

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.