Rozprawy doktorskie na temat „Sustainable crop production”

This thesis looks at the role of wild pollinators in providing services to crops. Two data chapters (2 and 3) are accompanied by a modelling chapter (4) which build on the findings of the field studies. The thesis ends with an overview of the trends in pollinator populations and how these relate to the needs of farmers in the UK (chap-ter 5). It is often assumed that commercial pollinators are appropriate substitutes of wild pollinators on farms; however this view neglects the differing roles that particular pollinator taxa might play in providing pollination services. For example, crops with a long growing system may require multiple pollinators to ensure pollination throughout the season. Strawberries in Scotland have an extremely long growing season, flowering from April to August. Chapter 2 presents a study showing season-al complementarity between different pollinating taxa across strawberry farms in Scotland. Pollinators of strawberries also differed in their responses to weather pa-rameters indicating that preserving multiple pollinator taxa could ensure yields un-der different weather scenarios. The requirements of a long-growing season and ad-verse weather may be specific to strawberry production in Scotland, but the valua-tion of multiple taxa can be generalised to systems with differing needs, and also to different ecosystem services. Wild bees are not only valuable for providing complementary services to commercial pollinators, but are also valuable in the longer term as it is unknown whether com-mercial pollinators will be available in the future. There are threats to the supply of honeybees which have already triggered price rises; such supply shocks could force farmers to leave production or to seek other ways of providing pollination, including supporting wild pollinators. However farm management pressures, in particular pes-ticide use, could threaten the ability of wild pollinators to continue to support crop production. The interplay of pesticides and pollination is discussed in chapter 3 and 4. Chapter 3 presents an experiment undertaken on soft-fruit farms which had and had not used the neonicotinoid, thiacloprid, and shows that nests exposed to thia-cloprid had higher worker mortality, and lower male production than those at con-trol farms. This has implications both for pollination services now, as worker mor-tality will reduce the number of bees visiting farms, and also for the maintenance of future pollination services through decreased reproductive capacity of exposed nests. Chapter 4 uses a theoretical model to link pesticide use and habitat use to pollina-tion services, and shows that the use of commercial pollinators could mask the de-cline in wild populations, making local extinctions more likely. Chapter 5 sets out the status and extent of pollinators in the UK, along with popu-lation trends, trends in habitat and trends in pesticide use to provide an overview of how well pollination services are likely to meet the ongoing needs of crop farmers.

L’intensificazione sostenibile delle pratiche agricole rappresenta un paradigma per il passaggio da sistemi agricoli tradizionali all’applicazione di tecnologie e tecniche moderne per la produzione agricola. A livello globale si è diffuso l’interesse verso il modello di Agricoltura Sostenibile (AS), in vista di alcuni problemi che possono minacciare la sicurezza alimentare mondiale: crescita della popolazione mondiale, cambiamenti nella domanda delle produzioni agricole, percentuale elevata di persone sottonutrite, cambiamenti climatici, diminuzione delle risorse naturali. Il progetto “Produzione di cibo appropriato: sufficiente, sicuro, sostenibile”, ancora in corso, lavora per raggiungere alcuni scopi: (1) rilevare e valutare la disponibilità quantitativa e qualitativa degli alimenti destinati al consumo umano, (2) proporre nuovi sistemi di produzione agro-zootecnica, (3) sviluppare tecniche appropriate per processare e conservare gli alimenti, al fine di ottenere uno stato di sicurezza alimentare e sostenibilità ambientale ed economica. L’obiettivo generale di questo lavoro è quello di mostrare quali sono le possibili alternative ai sistemi agricoli tradizionali, sia nei Paesi Sviluppati sia in quelli in Via di Sviluppo, al fine di aumentarne l’efficienza e diminuirne gli impatti sull’ambiente, aumentando lo stato globale di sicurezza alimentare. Per i Paesi in Via di Sviluppo l’attenzione si concentra sulle pratiche di sviluppo rurale integrato, al fine di implementare quantitativamente la produzione alimentare e, conseguentemente, la sicurezza alimentare, preservando nel contempo l'ambiente. Per i Paesi Sviluppati, in cui i rendimenti agricoli sono già potenzialmente molto elevati, l’attenzione viene focalizzata sul migliorare la produttività del suolo, riducendo gli input esterni e le emissioni di gas ad effetto serra, attraverso l’adozione di sistemi agricoli conservativi.
Sustainable intensification of agricultural practices represents a paradigm shift from traditional farming systems to the application of modern technologies and techniques to crop production. At global level it has been widespread interest towards Sustainable Agriculture (SA) model, in view of some issues that will may threaten the world food security: growing world population, changes in agricultural product’s demand, high prevalence of undernourishment, climate changes, decreasing of natural resources. The project “Production of proper food: sufficient, safe, sustainable" is still working to achieve some purposes: (1) to detect the availability quantity and quality of food for human consumption, (2) to propose new agro-livestock production systems, (3) to develop appropriate techniques for processing and storage of foodstuffs, in order to achieve food security, environmental and economic sustainability. The objective of this work is to show what are the possible alternatives ways at traditional agricultural systems, both in Developed and Developing Countries, in order to increase the efficiency and to decrease the impacts on the environment, raising a global condition of food security. For Developing Countries the attention is focused on integrated rural development practices in order to implement food production and the state of food security, while preserving the environment. For Developed Countries, in which yields are already potentially higher, the attention is focused on enhance soil productivity while reducing external farming input and greenhouse gases emission by the adoption of conservation agricultural systems.

The Food and Agriculture Organization of the United Nations predicts that food supplies will need to increase by 70 percent by 2050. To cope with this, farmers and technologies must adapt to produce higher yields and do so in harsher conditions associated with climate change. The shifting view of ultraviolet radiation may be one of a system of management approaches that agriculture could sustainably adopt to improve crop production. While this technology sounds promising, whether or not farmers choose to adopt the technology, on what scale, or when, is often ambiguous. These decisions are dependent on social, economic, and biophysical factors that can be identified for UV radiation technology. This technology is not ready for full adoption, but there may be some feasible applications in higher value crops like fruit and vegetables.

The study focuses on investigating the impact of crop production to sustainable livelihood strategies among rural women. The main objective of the study are as follows: to investigate the extent to which Silwindlala crop production cooperative has improved the lives of Jerseyville rural women, to investigate the new skills that Jerseyville rural women have obtained from Silwindlala crop production cooperative, to explore on challenges that would contribute to failure of crop production cooperative and to come up with the recommendations that would contribute to policy formulation and skills on management of crop production cooperative of rural women. The study employed qualitative method for data collection and analysis. The main findings of this study were that, the impact of crop production on sustainable livelihood is still seasonal, during harvesting period. Data showed low educational status and lack of business management skills among rural women, however, technical skills and collective interest contributed to the success of the cooperative

The first essay formulates a dynamic general equilibrium optimal control model of an energy crop as part of a country's planned resource use over a period of time. The model attempts to allocate consumption, production, and factors of production to achieve the country's sustainable development goal. A Cobb-Douglas specification is used for both utility and production functions in the model. We calibrate the model with Thailand data. The selected model is used to generate the stationary state solution and to simulate the optimal policy function and optimal time paths. Two methods are used: a linear approximation method and the Runke-Kutta reverse shooting method. The model provides numerical results that can be used as information for decision makers and stakeholders to devise an economic plan to achieve sustainable development goals. The second essay studies the effect of international trade and changes in labor supply, land supply, and the price of imported energy on energy crop production for bio fuel and food, as well as impacts on social welfare. We develop a dynamic general equilibrium model to describe two baseline scenarios, a closed economy and an open economy. We find that international trade increases welfare and decreases the energy price. Furthermore, resources are allocated to produce more food under the open economy scenario than the quantities produced under a closed economy assumption. An increase in labor supply and land supply result in an increase in social welfare. An increase in imported energy price leads to a welfare loss, higher energy production, and lower food production. The third essay develops a partial equilibrium econometric model to project the impacts of an increase in ethanol production on the Thai agriculture sector over the next ten years. The model is applied to three scenarios for analyzing the effect of government ethanol production targets. The results from the baseline model and scenario analysis indicate that an expansion in ethanol production will result in a significant increase in cassava production, price, and land use. The increase in cassava production will shift land use from maize and sugar cane, thus increasing in price of maize.

A series of experiments were conducted to determine the potential of a new method of steam treatment for the control of soil-borne diseases, insects and weeds in sustainable crop production.  The new method involved rapidly heating a bed of prepared soil on a porous base by passing an upward flow of steam through it.  The aim was to determine whether the new method would be suitable for use in a field machine, making large-scale field steaming practically and economically viable. In the first experiments, the feasibility of the new method was tested.  It was shown that it was an effective and rapid way in which a soil bed could be steamed.  However, for some soils at, or near, permanent wilting point, the entrainment of aggregates in the steam flow was shown to be a problem.  The second series of experiments showed that the key factor determining the flow rate at which aggregate entrainment occurred was the mean aggregate diameter of the soil being treated.  The third series of experiments examined the rate at which heated soil would cool when placed in the field.  It was shown that where there was contact with unheated field soil, cooling was very rapid.  The final series of experiments investigated the effects of the new steaming method on the soil.  A three minute steaming time was used to account for the short time it had been shown some of the heated soil would remain at steam temperature when replaced in the field.  The effects of the new method, including the effectiveness of disinfection, were shown to be similar to those of a conventional steam treatment. It was concluded that the new steaming method was an effective way to steam treat soil and should be suitable for use in a field machine.

In the context of global energy shortage and climate change, developing local biogas plants coupled with agricultural systems can become an important strategy for cleaner rural energy and sustainable agriculture. In this research, a Life Cycle Assessment (LCA) method was applied to compare the climate impact of two essentially different systems: 1) Scenario I: an agricultural system based on the cultivation of 11 hectares of energy tobacco primarily for seed production; 2) Scenario II: a hypothetical Scenario Investigating the climate impact concerned with a crop variety – a higher yielding variety cultivated for both seed and biomass - and introducing biogas production. Both scenarios focus on the energy tobacco biomass residues. The overall aim of the study was to evaluate the climate impact of these two scenarios in the agricultural and energy system in Marble Hall, Limpopo Province, South Africa. The biogas was used for electricity production, replacing coal-based electricity on the grid. Biomass residues were chosen as feedstock for biogas production since this crop presently receives much attention in the region as the oily seeds can be used to produce sustainable jet fuel. Results from the modelling show that Scenario II would provide a positive climate impact: a 43% reduction of greenhouse gases compared to Scenario I. The higher yielding crop variety in Scenario II means that there is also potential to produce more sustainable jet fuel to replace conventional aviation fossil fuel. Taking this into account, the biogas scenario can reduce emissions by 79% compared to the base case. An analysis of the results indicates that there are several variables in the system model that are uncertain and sensitive to change, proving that more research is necessary to make robust conclusions about the validity of the presented results.

There is a remarkable growth in the field of Information Communication Technology (ICT) in Developing Countries (DCs). Telecommunication is one of the areas where ICT is recording an ongoing rapid change. Mobile phones are becoming pervasive in daily scenario; and among the beneficiaries of this are farmers. Farmers are using mobile phones in executing their farming business and daily life. At the same time, Wireless Sensor Networks (WSNs) are also showing a result in developed part of our world. WSNs potential in sensing various environmental condition, their affordability and applicability motivated conducting of this master thesis. Therefore, the objective of conducting this master thesis is to investigate and identify how the use of mobile phones in conjunction with WSN enable farmers in Ethiopia monitor and control their farm field. We use firsthand qualitative data we gathered during our field work in Ethiopia to design our proposed prototype. Functional requirements and system design guideless are obtained from observation we make and interviews we carry out on irrigation based farmers around town of Meki in region of Oromia. We use our prototype to demonstrate and evaluate how irrigation based farmers benefit from existence of such system.

The location of cones in crowns of grafts and mature planted tress was studied in detail and relationships between cone type and shoot characteristics were investigated. The results enabled a regression model to be developed to relate cone counts in certain crown zones to overall cone bearing. It was demonstrated that there are patterns of cone production in the crowns of Picea sitchensis. Preferred zones for female bearing are high in the tree. Male cones tend to occur lower in the tree and more proximal to the stem than female cones. As total female cone production increases, cones are borne progressively further down the tree and towards the main stem. In all cases there were shoots that remained vegetative, regardless of total cone bearing. There were also interactions between the type of cone and the nature of the bearing shoot. On lower order shoots both male and female cones tended to be borne in the proximal lateral position. On progressively weaker shoots there is a tendency for cones to be borne in progressively more distal positions. The same progress of cone bearing - from proximal to distal positions - occurred on shoots of decreasing size. On forest trees the vast majority of cones are borne on trees of above average dimensions. Of the three measured variables (height, dbh and crown depth) height appeared to be the most important in influencing cone production. Prognostic tree and stand models were developed which were quite successful in predicting cone production in forest stands, particularly at low or zero levels of bearing. The presence of female cones on the bearing shoots affected both the development of more proximal buds on that shoot and the characteristics of offspring shoots. Offspring shoots on bearing parents were smaller and tended to bear fewer needles. The effect on the number of buds formed was not conclusive.

South Africa and other developing countries are grappling with high levels of poverty as a result of slow to negligible rural development. Irrigation development is one essential component that can be used to address the challenges faced by smallholder farmers in rural areas. In the President‟s “State of the Nation Address” in 2011, the President of South Africa outlined measures to reduce hunger and poverty in communal areas through enhanced government‟s expenditures in rural infrastructure developments, especially for such amenities as irrigation and roads, with a view to promoting food security. The broad objective of this study is to assess livelihood strategies and opportunities with regard to farming in Qamata area of Intsika Yethu Local Municipality. The stratified random sampling method was applied in order to choose a sample of 70 household that were interviewed by means of semi-structured questionnaires. Out of these, 53 belonged to the irrigation project and 17 farmers were non-irrigation farmers. The results show that women play an active role in agriculture. The Multiple Regression model was used to assess the relative importance of different livelihood strategies adopted by both irrigation and non-irrigation farmers in improving household food security and welfare in Qamata. More specifically, the study assessed the impact of different livelihood strategies on production of butternut, goats, maize and poultry (Chicken) in Qamata. The results show increased agricultural production, crop diversification and higher incomes from irrigation farming as compared to dry land farming. Irrigation farming has enabled many households to diversify their sources of income and therefore include activities and enterprises that contribute to enhanced household welfare. The study showed that household size is crucial in crop production, followed by gender of the household head. The government and research institutes need to come up with programmes to train people on ways to produce crop and livestock products more efficiently.

This study was undertaken to research the principles and practices behind increased pasture productivity on Longslip Station, Omarama. A range of landscape - soil - climate - plant systems were identified, then analysed and the legume responses measured. By isolating cause and effect and appreciating the driving variables of each system, lessons learnt could be reliably and objectively transferred to the rest of the farm. Extrapolation to the balance of the property (15,150 ha) permitted immediate large-scale development and engendered confidence to lending institutions, Lands Department, catchment authorities and ourselves. Soil (land) cannot be well managed and conserved unless it is mapped reliably and its characteristics measured and interpreted by skilled observers (Cutler, 1977). Soil resource surveys, and their interpretation, are an essential ingredient of rational resource evaluation and planning. This thesis is a figurative and comparative survey and study of the soil catenary bodies, resident vegetation, legume establishment and pasture production characteristics of a 400 hectare catchment, in relation to, and as influenced by soil landscape unit, slope component, altitude, aspect and time. The inherent diversity in landform, soil properties and vegetation communities in a single catchment in the high country has not previously been fully studied or appreciated. This has lead to blanket recommendations for fertilizer, seed and management regimes both within and between properties and even regions. This study reports on the diversity of, yet predictable change in soil properties with slope position (upper, middle and lower) aspect and altitude in terms of both soil physical properties e.g. soil depth and water holding capacity and soil chemical properties such as pH, BS%, %P, %S, %N and %C. The composition of the resident vegetation and its differential response to oversowing and topdressing and subsequent change through time is reported and discussed. Finally an epilogue gives an insight into the problems and frustrations of farming practices in the high country from a motivation and personal perspective and political point of view that it is essential to come to terms with.

Both globally and locally, agriculture faces ever increasing challenges such as high input costs, strict environmental laws, decrease in land for cultivation and an increase in demand due to the growing global population. Profitability and sustainability requires more effective production systems. Precision agriculture is identified as such a system and is built upon a system approach that aims to restructure the total system of agriculture towards low input, high efficiency and sustainable agriculture. The aim of this study was to analyse the state of precision agriculture in the summer grain producing areas of South Africa, specifically the North West and Free State provinces. In order to achieve this, a literature study was conducted. During the literature study the term ‘precision agriculture’ was defined and discussed. The precision agriculture cycle and its components were explained and benefits of precision agriculture were identified. The literature study was concluded with identifying and discussing the most widely used and most beneficial technologies as well as reasons for slow adoption. Findings from the literature study were used to investigate the state of precision agriculture locally. In order to achieve this, a quantitative approach was used and information was collected by means of an empirical study using a questionnaire. Questionnaires were distributed to farmers using selling agents of an agricultural company that is well represented in the targeted areas. The data was then statistically analysed. The survey showed that only 52% of summer grain producing farmers in the North West and Free State provinces of South Africa practises precision agriculture as defined in the v literature study. The study also revealed that the majority of precision agriculture farmers are over the age of 40, have more than 16 years of farming experience, are well educated, cultivate more than 1,000 hectares and uses none or little irrigation. The most commonly used precision agriculture technologies were grid soil sampling and yield monitors. The perception among most of the farmers was that precision technologies are not very affordable, not easily available and that it lacks proper testing with regards to efficiency. The group of summer grain–producing farmers that have correctly implemented precision agriculture as per definition stated that the benefits they derived from precision technologies include reduction in input costs, increased outputs and improved management skills. Too high implementation costs and technologies not providing enough benefits were among the main reasons farmers do not implement precision agriculture. It was concluded that a significant effort and amount of work is needed to increase the use of precision agriculture among summer grain–producing farmers in the targeted areas. A consolidated effort from government, agricultural institutions and agricultural companies will be needed to achieve this goal. Implementing precision agriculture as a system will require education (from primary to tertiary institutions) and improved marketing strategies. Only then will precision technologies be able to help meet the future demands placed on the agriculture sector.
Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

Thesis (PhD(Agric) (Agronomy))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Continuous cropping without replenishing the nutrient component of soils will eventually lead to the depletion of soil nutrients. Small scale farmers in Zimbabwe often do not have the financial means to buy fertilizer and this problem is exacerbated by scarcity of commodities such as fertilizers. The use of herbaceous legumes such as mucuna (Mucuna pruriens) can assist to recapitalize soil fertility depletion and improve subsequent maize productivity in sandy loam soils in the small holder farming sector of Zimbabwe. In this study the effect of phosphorus (P) application to a mucuna crop, the effect of mucuna management options and the application of nitrogen (N) to the subsequent maize crop was investigated. The experiment was carried out during the 2007 to 2009 seasons at the Grasslands Research Station in Marondera in Zimbabwe. The soils are classified as humic ferrolsols and are predominantly of the kaolinitic order with sandy loams of low fertility and are slightly acid (pH CaCl = 5.2). A randomized complete block design was used for the effect of P on mucuna productivity and the effect of P and mucuna management options on the soil properties. The treatments were two P rates (P0 and P40 = 0 kg P ha-1 and 40 kg P ha-1 respectively) applied to a preceding mucuna crop, four mucuna management options [1) fallow (F) (no mucuna planted = control), 2) mucuna ploughed-in at flowering (MF), 3) all mucuna above ground biomass removed at maturity and only roots were ploughed-in (MAR) and 4) mucuna pods removed and the residues ploughed-in (MPR)]. A split-plot design was used to study the effect of P application to mucuna, mucuna management options and N rates on the growth and yield of the subsequent maize crop. The four N treatments [N0 = 0 kg N ha-1, N40 = 40 kg N ha-1, N80 = 80 kg N ha-1 and iv N120 = 120 kg N ha-1] were applied to a subsequent maize crop. Growth and development parameters such as biomass production, leaf area index, nutrient content of the foliage and grain yield were determined in the mucuna and maize crops. Soil parameters investigated included nutrient content, pH, bulk density and porosity. Phosphorus application in these particular soil conditions positively influenced mucuna biomass production and therefore enhanced the role of mucuna as a rotational crop by increased positive effects on the subsequent maize crop. The incorporation of above-ground biomass of mucuna had positive effects on all soil properties investigated. The MF and MPR management options increased the soil organic matter (OM) and reduced bulk density which leads to an improvement in porosity (f) of the soil. Mucuna incorporated at flowering (MF) and P40 treatment combination resulted in the highest mineral N, P, potassium (K), calcium (Ca) and magnesium (Mg) levels. A significant three-way interaction (P<0.05) between mucuna management options, nitrogen rates and time was observed in terms of biomass production and all nutrients in the leaves of the subsequent maize crop. The main findings were that the MF management option had the highest biomass and foliar nutrient accumulation through-out all the treatment combinations. In general the MF management option gave the highest maize yield across all the treatment combinations. Incorporation of mucuna biomass into the soil prior to planting a maize crop therefore improve soil physical and chemical qualities resulting in improved soil conditions for a subsequent maize crop which in turn lead to higher maize yields. Including a mucuna rotational crop have a similar effect on maize yield than application of 80 kg ha-1 of fertilizer N.
AFRIKAANSE OPSOMMING: Aanhoudende verbouing van gewasse op dieselfde grond sonder om voedingstowwe aan te vul lei uiteindelik tot die agteruitgang van die grond se vrugbaarheid. Kleinboere in Zimbabwe het meestal nie die finansiële vermoëns om bemestingstowwe te koop nie en die probleem word vererger deur die onbekombaarheid van kommoditeite soos bemestingstowwe. Die gebruik van kruidagtige peulplant gewasse soos mucuna (Mucuna pruriens) kan bydra om grondverarming teen te werk en om die produksie van ‗n daaropvolgende mielie aanplanting in sandleemgronde in ‗n kleinboerstelsel in Zimbabwe te verhoog. In hierdie studie is die invloed van fosfor (P) toediening aan ‗n mucuna aanplanting, die invloed van bestuursopsies van die mucuna en die toediening van stikstof (N) aan die daaropvolgende mielie aanplanting ondersoek. Die eksperiment is tydens die 2007 tot 2009 reënseisoen by die Grasslands Research Station in Marondera in Zimbabwe uitgevoer. Die grond word geklassifiseer as humiese ferrolsols en is hoofsaaklik sanderige leemgrond van die kaolinitiese orde met lae vrugbaarheid en is effens suur (pH CaCl = 5.2). ‘n Volledig ewekansige blokontwerp is gebruik om die invloed van P op die produktiwiteit van mucuna te bepaal asook die invloed van P toediening en mucuna bestuursopsies op grondeienskappe. Die behandelings was twee P vlakke (P0 = 0 kg P ha-1 en P40 = 40 kg P ha-1) wat aan ‗n voorafgaande mucuna aanplanting toegedien is, vier mucuna bestuursopsies [1) braak (F) (geen mucuna geplant = kontrole), 2) mucuna ingeploeg met blomtyd (MF), 3) alle bogrondse mucuna biomassa verwyder by rypwording en slegs wortels ingewerk (MAR) en 4) mucuna peule verwyde en die res van die bogrondse material ingeploeg (MPR)] en vier N behandelings [N0 = 0 kg N ha-1, N40 = 40 kg N ha-1, N80 = 80 kg N ha-1 en N120 = 120 kg N ha-1] toegedien aan ‗n daaropvolgende mielie aanplanting. Groei en ontwikkeling parameters soos biomassa produksie, blaaroppervlakindeks, nutriëntinhoud van die blare en graanopbrengs is in die mucuna en mielie aanplantings ondersoek. Grondeienskappe soos nutriëntinhoud, pH, bulkdigtheid en porositeit is gemeet. Fosfaat toediening aan hierdie spesifieke grondtipe het mucuna produksie positief beïnvloed en dus die rol van mucuna as rotasiegewas verbeter deur positiewe reaksies in die daaropvolgende mielie aanplanting. Die inwerk van bogrondse mucuna biomassa het al die fisiese grondeienskappe wat ondersoek is positief beïnvloed. Die MF en MPR bestuursopsies het organiese materiaal inhoud van die grond verhoog en bulkdigtheid verlaag wat lei tot verbeterde grondporeusheid (f). Mucuna wat tydens blomvorming ingewerk is (MF) lei tot die hoogste minerale N, P, kalium (K), kalsium (Ca) en magnesium (Mg) vlakke. ‗n Betekenisvolle drie-rigting interaksie (P < 0.05) tussen mucuna bestuursopsies, N vlakke en tyd is waargeneem in terme van biomassa produksie en in terme van al die nutriëntvlakke in die mielieblare wat ondersoek is. Die hoofbevindinge was dat die MF bestuursopsie die hoogste biomassa produksie en blaarnutriënt akkumulasie oor alle behandelingskombinasies tot gevolg gehad het. In die algemeen het die MF bestuursopsie die hoogste mielie-opbrengs oor alle behandelingskombinasies tot gevolg gehad. Die inwerk van mucuna materiaal in die grond voordat mielies geplant word verbeter dus fisiese en chemiese toestande in die grond wat grondtoestande verbeter vir die daaropvolgende miegewas en uiteindelik lei tot hoër mielie-oeste. Die insluiting van mucuna as ‘n rotasiegewas het diesefde effek op mielie-opbrengs as die toediening van 80 kg ha-1 N bemesting.

The world is about to shift from fossil fuel dependency to independency. The national agenda of Sweden has put forth future goals of becoming a zero net greenhouse gas emitter by the year 2045 and before that, having an 80 % fossil fuel independent transportation fleet by 2030. In order to achieve these goals, the form of energy used in the transport sector needs to be changed into a more renewable solution. Biogas could be part of the solution. The aim of this report has been to review earlier research regarding the future biogas potential in Sweden and to examine how realistic and practically feasible these are. Three of the substrates that has shown the highest future potential according to earlier research; energy crops, manure and black liquor has been chosen for investigating their future potential. Interviews was made with biogas researcher in Sweden as well as government employees working with biogas and other biofuels. Scenario building was another method used were the report have created four future scenarios with varying optimistically future economic and technical outcomes using more practical limitations and restrictions. The result was a combined future potential of between 0,42 – 77,54 TWh/annually from all three substrates using the values and information gathered from the interviewers regarding how to calculate the potential. The result shows that depending on how lucrative the future financial support systems and subsidies as well as how efficient the technical breakthroughs will be, biogas can become a large contributor to the transport sectors transition in becoming less fossil fuel dependent.

Fall-planted forage radish (Raphanus sativus L. longipinnatus) cover crops have shown successful weed suppression and recycling of fall-captured nutrients. This research evaluated the nutrient cycling and weed suppressive benefits of forage radish cover crop mixtures to develop an integrated system for no-till sweet corn (Zea mays L. var rugosa) production that improves crop yield and soil health. Treatments included forage radish (FR), oats (Avena sativa L.) and forage radish (OFR), a mixture of peas (Pisum sativum subsp arvense L.), oats and forage radish (POFR), and no cover crop control (NCC). Subplots were assigned to nitrogen fertilizer treatments to evaluate N sufficiency and timing: 0 kg N ha-1 as the control, 28 kg N ha-1 at side-dress, and 56 kg N ha-1 with application split between planting and side-dress. Results indicated that POFR and OFR provided improved N cycling and sweet corn yield compared with FR and NCC. Early season N from decomposing cover crop residue was sufficient to eliminate the need for N fertilizer at sweet corn planting, thereby reducing input costs and risks of environmental pollution.

In Lombok (Indonesia), annual cropping patterns in irrigated areas are divided into three cropping cycles of four months each. In better irrigation schemes, there are normally two irrigated flooded-rice crops, i.e. wet season and dry season lowland rice crops in sequence, followed by one non-rice crop cycle during the driest months (this is referred to as the twice-rice system). In less developed irrigation schemes, one lowland rice crop is normally grown during the rainy season, followed during the driest months by two cycles of non-rice crops, or a non-rice crop and a fallow (this is referred to as the once-rice system). In rainfed areas, especially in the vertisol soil areas, there are upland rice systems in the highland or hillsides, and “Gora” (dry seeded-flooded) rice systems in the lowland. In this area, rice is grown only once a year during the rainy season of the monsoon. Farmers in Lombok do not normally fertilise the non-rice crops such as soybean and mungbean grown following rice, and application rates of fertiliser to rice have fallen since the economic crisis in 1998. Therefore phosphorus (P) deficiency may be expected, which may explain the very low yields of soybean and mungbean achieved by farmers in Lombok. With low P, arbuscular mycorrhizas (AM) might be expected to play an important role in plant nutrition, but inoculation with arbuscular mycorrhizal fungi (AMF) increased root colonisation and yield of these crops in a recent field experiment in Lombok. There had been no survey of AMF populations in rice-based systems in Lombok prior to the work reported here, and little such work anywhere internationally. Therefore, an extensive survey was conducted in Lombok on the two main soil types with rice-based systems. Another field survey was conducted in the Riverina rice-growing area (Australia), as a comparative study to the Lombok survey. In Lombok, rice systems with longer total annual flooding duration had lower populations compared with upland or Gora rice systems. It was therefore suggested that the lower colonisation level in flooded rice was due to the flooded conditions, as well as soil chemical properties associated with flooded conditions, rather than the rice plant itself. There are options for improving AMF population for better growth of non-rice rotation crops, or even for rice crop in Lombok as fertilisers become less affordable and their use on flooded rice is declining. The easiest option is to inoculate AM fungi in the nursery or to make nursery beds in a paddock previously cropped with AMF-stimulating species, such as soybean, to start infection on rice seedlings, which should be better with a dry nursery. The second option is to modify the technique of growing rice, such as applying the SRI (System of Rice Intensification) principles, in which rice is grown without flooded conditions but intermittent short flooded and upland conditions. This will keep the soil in an aerobic condition much of the time and should facilitate the development of beneficial microbial populations and activities in the soil, such as AMF and nitrogen fixers. The SRI method has been reported to increase rice yield dramatically, even in soil with low fertility levels.
Doctor of Philosophy (PhD)

In Lombok (Indonesia), annual cropping patterns in irrigated areas are divided into three cropping cycles of four months each. In better irrigation schemes, there are normally two irrigated flooded-rice crops, i.e. wet season and dry season lowland rice crops in sequence, followed by one non-rice crop cycle during the driest months (this is referred to as the twice-rice system). In less developed irrigation schemes, one lowland rice crop is normally grown during the rainy season, followed during the driest months by two cycles of non-rice crops, or a non-rice crop and a fallow (this is referred to as the once-rice system). In rainfed areas, especially in the vertisol soil areas, there are upland rice systems in the highland or hillsides, and “Gora” (dry seeded-flooded) rice systems in the lowland. In this area, rice is grown only once a year during the rainy season of the monsoon. Farmers in Lombok do not normally fertilise the non-rice crops such as soybean and mungbean grown following rice, and application rates of fertiliser to rice have fallen since the economic crisis in 1998. Therefore phosphorus (P) deficiency may be expected, which may explain the very low yields of soybean and mungbean achieved by farmers in Lombok. With low P, arbuscular mycorrhizas (AM) might be expected to play an important role in plant nutrition, but inoculation with arbuscular mycorrhizal fungi (AMF) increased root colonisation and yield of these crops in a recent field experiment in Lombok. There had been no survey of AMF populations in rice-based systems in Lombok prior to the work reported here, and little such work anywhere internationally. Therefore, an extensive survey was conducted in Lombok on the two main soil types with rice-based systems. Another field survey was conducted in the Riverina rice-growing area (Australia), as a comparative study to the Lombok survey. In Lombok, rice systems with longer total annual flooding duration had lower populations compared with upland or Gora rice systems. It was therefore suggested that the lower colonisation level in flooded rice was due to the flooded conditions, as well as soil chemical properties associated with flooded conditions, rather than the rice plant itself. There are options for improving AMF population for better growth of non-rice rotation crops, or even for rice crop in Lombok as fertilisers become less affordable and their use on flooded rice is declining. The easiest option is to inoculate AM fungi in the nursery or to make nursery beds in a paddock previously cropped with AMF-stimulating species, such as soybean, to start infection on rice seedlings, which should be better with a dry nursery. The second option is to modify the technique of growing rice, such as applying the SRI (System of Rice Intensification) principles, in which rice is grown without flooded conditions but intermittent short flooded and upland conditions. This will keep the soil in an aerobic condition much of the time and should facilitate the development of beneficial microbial populations and activities in the soil, such as AMF and nitrogen fixers. The SRI method has been reported to increase rice yield dramatically, even in soil with low fertility levels.

Yield decline following continuous cropping cycles in Central Queensland has been attributed to the declining soil nitrogen status. In this study an assessment of the level of nitrogen fixation was made to assist in the selection of potential ley pasture legumes for use in rotational systems to achieve sustainable cropping yields.

Twenty one winter and summer growing legumes were evaluated for nitrogen fixation in glasshouse trials in two seasons. Nitrogen fixation was determined using the hydrogen evolution technique (an instantaneous measure of fixation rate) in an artificial media trial and the 15N natural abundance technique (an integral measure of fixation) in a soil based trial.

The prospects of sustainable crop production technologies in East Timor were discerned with relevant case studies and experimental data. An overview of the agricultural development in East Timor with particular emphasis on the traditional farming and cropping systems was presented complemented by the discussion on the aspects of agricultural mechanization and technological change and their socioeconomic ramifications on food security. Empirical data from tillage trials, established both in East Timor and New Zealand, were gathered and discussed in the quest for a better understanding of tillage effects on soil structure and crop production environment. The agro-climatic zones of East Timor provide a well-defined set of ecological boundaries upon which further collaborative research work can be developed. Given land resources as one of the major capital investments in agriculture development, the drive towards improvement and technical change in agriculture should be directed in a balanced combination, whenever appropriate, between technologies of land-saving (hybrid seeds, irrigation, and drainage) or labour-saving (mechanization, herbicides, varieties and cropping techniques) characteristics. Moreover, the justification for acquiring an improved technology for traditional farmers, to some extent, needs to conform to the features of their subsistence mode of farming. The emphasis in technology dissemination, therefore, will have to shift from communication to education. Experimental results of this study on the effects of tillage, and no-tillage in Particular as a form of conservation tillage, on the edaphic changes affecting cropping environment generally concur with the findings known in the literature. Organic carbon levels are generally restored with cropping in East Timor. In addition, soil bulk density and crop grain and biomass yield were not affected by tillage treatments. Soil compaction was significantly affected by tillage as shown by data from the Palmerston North experiment. Soil aggregate stability in the 0-10 cm topsoil was similar under all the tillage treatments. Manual tillage (MT) had the greatest number of soil aggregates on sieve after a 30-minute wet-sieving (68.3%) followed by no-tillage (NT) (65.1), permanent pasture (PP) (62.6) and conventional tillage (CT) (56.5). Similarly, the top 0-10 cm soil under MT had significantly larger macroporosity (16.4%) than CT (9.23), NT (11.5), and PP (10.6). MT and CT significantly reduced the total C whereas N levels were significantly decreased by tillage (CT, MT and NT) compared to permanent pasture at the top 0-10 cm soil layer. Barley grain and biomass were unaffected by tillage whereas potato tuber yield and biomass were significantly less under no-tillage. Conventional tillage significantly increased water runoff but produced less leachate compared to no-till and permanent pasture. Total soil sediment loss was significantly lower under PP (95.8 kg/ha) and NT (132.9) compared to CT (3556.7) and MT (4652.2). pH of water runoff was significantly reduced under tillage treatments compared to that from permanent pasture whereas nitrogen losses were unaffected. There are at least four major public policy components that will play vital roles in the development of sustainable crop production technologies in East Timor: (i) Agricultural research and development (ii) Agricultural extension (iii) International and regional networking (iv) Shift of policy focus. The policy approach needs to be decentralized and broad-based and conservation agriculture should be promoted as opposed to conventional production agriculture. Three major areas for the future research agenda include: (i) Integrated Farming Systems (ii) Soil tillage and erosion (iii) Applied science and technology. The last component may cover disciplines such as: food policy analysis, farm machinery selection and testing, soil testing and mapping, land evaluation and GIs, bio-energy technologies, improved local seed varieties, adaptive fodder crops for improved grazing and pasture management, appropriate agro-forestry and soil and water conservation technologies and cash crop initiatives.

The primary aim of my research was to identify the impacts and adaptation options of climate variability and change on agricultural production in Limpopo province. The following objectives were identified: To understand the impacts of climate variability and change on agricultural production in Limpopo province , To assess the impacts of climate variability and change on agricultural production in Limpopo province and To identify adaptation measures that reduces the impacts of climate variability and change on agricultural production in Limpopo province. A representative sample of 300 farmers aged 16- 65+ years (46 percent males and 54 percent females) participated in the study. The study involved Sekhukhune and Capricorn districts, with 56 percent farmers in Capricorn and 44 percent in Sekhukhune district. The following 11 local municipalities were visited: Elias Motsoaledi, Makhuduthamaga, Fetakgomo, Ephraim Mogale, Tubatse, Lepelle Nkumpi, Blouberg, Aganang, Polokwane, and Molemole. The Limpopo province is one of the poorest provinces in the country, characterized by high unemployment rate, poverty and lack of access to a range of resources that frustrate majority of people ability to secure their livelihoods. In this study the province's economic, biological and physical environment were highlighted. The study further covers the province, s farming enterprises, systems, categories, infrastructure as well as other constraints that maybe facing the emerging farmer in the province. It is assumed that the majority of farmers in both the Capricorn and Sekhukhune districts are using different coping and adaptation strategies in order to increase their crop yields. Literature studies show that climate variability and change adaptation strategies vary from area to area due to agro ecological zones and the harshness of the effects of climate variability and change. It has also been noted that climate change is fast pushing the poorest and most marginalized communities beyond their capacity to respond. This study draws on lessons learned, experiences, and other existing research on climate change impacts and adaptation across the globe. It sets out what is needed to enable people living in poverty to adapt to climate change, and a range of interventions that are available across climate - sensitive sectors. The study has provided a literature review of the impact of climate change on the agricultural sector. In fact, it has documented some of the likely impacts of climate change based on International, continental, regional, national and provincial agricultural sector. The study highlighted the impact of climate change also on various climate - sensitive sectors including understanding water resources, forestry, natural ecosystem human health, infrastructure and coastal zones. This research also confirmed that being a full time farmer, gender, information on climate change, information received through extension services and adaptation to climate change are some of the important determinants of agricultural production, food scarcity and unemployment. A worrying situation is reviewed globally in this study and it can be concluded that climate variability and change is affecting every sector in society and it needs urgent attention. Statistics was used to determine climate variability and change impact on agricultural production. Results indicate that farmers are aware that Limpopo province is getting warmer and drier with increased frequency of droughts, changes in the timing of rains, observed trends oftemperature and precipitation. The study also presented perceived adaptation strategies used by farmers in Limpopo province. Some of their perceived adaptation strategies included: (a) Soil management strategies, (b) Water management strategies and (c) Others like use of subsidies and use of insurance. Other important adaptation options being used by farmers were also discussed in this study including different adaptation measures against colds, heat, frost, abnormal wind, hail, lack of extension support, nematodes, insecticides, worms, temperature and rainfall. The results of this study are potentially valuable to the agricultural sector considering the threats that climate change poses across climate sensitive sectors.
Environmental Sciences
D. Phil. (Environmental Management)

The impacts of climate change on water resources and agriculture, accompanied by a growing population, have contributed to increasing food and water scarcity. Due to the continuing growth in population and changes in food requirement habits, the demand for agricultural products is increasing continuously. It has been projected that the rise in food demand will increase by 50-100% between 2009 to 2050. The irrigation sector plays a crucial role in the agricultural food production system, utilizing about 70% of the world‘s total annual water consumption. About 16% of the world‘s cropland is irrigated, accounting for about 44% of the world‘s food production. Climate variability influences water availability for agriculture, crop water demand, and crop grain yield, rendering global food security vulnerable to climate change. Research has shown that South Asia will face negative impacts on agriculture due to climate change, and food scarcity will increase if adaptation measures are not considered. In this regard, there is a need to investigate existing irrigation schemes by assessing the impacts of climate change on both the supply and demand sides of irrigation water simultaneously to cope with changes in future water availability and food scarcity. This research aims to holistically investigate the climate change impacts on both the supply and demand sides of irrigation water. The methodology developed in this research investigated climate change impacts on the supply and demand sides of irrigation water in the Sunsari Morang Irrigation Scheme in the Koshi River basin of Nepal. The irrigation command area is 68,000 hectares. With this background, the objective of this research is to assess the climate change impacts on the supply and demand sides of irrigation water. This research is divided into four major components. 1. Selection of global climate models and downscaling of global climate model outputs to assess climate change impacts on daily rainfall and temperature (minimum and maximum) in the river basin and irrigation command area. 2. Future impacts of climate change on river water availability at the main irrigation canal intake. 3. Crop water requirements due to climate change. 4. The irrigation canal system‘s hydraulic capacity requirements for irrigation water supply in the climate change context. Climate change is the main driver in assessing river water availability for irrigation, crop irrigation requirements, and canal system capacity needs for the future. In this study, climate change scenarios Representative Concentration Pathways (RCPs) 4.5 and 8.5 for the short-term (2016–2045), mid-century (2036–2065), and end-of-century (2071–2100) periods were considered. Representative General Circulation Models (GCMs) were selected for the study area under each climate change scenario and study period. Daily precipitation and temperature data based on selected GCMs were downscaled to a higher resolution (10 × 10 km2). The downscaled daily precipitation and temperature data were applied to assess the climate change impacts on water availability in the river, and irrigation water demand in the irrigation command area. The irrigation canal system capacity assessment was based on water availability in the river, and irrigation water demand. The selection of global climate models for a specific geographical location, with high capacities to represent the past and to project the likely future climate, is a crucial step when assessing climate change impacts. An advanced envelope-based selection approach for the selection of a representative global climate model has been used in this research to select a representative climate model for the Koshi River basin. A total of 105 GCM simulations and 78 GCM simulations were taken for RCP4.5 and RCP8.5 scenarios respectively for the initial selection of GCMs. The GCMs selection process involved three steps: (a) initial model selection considering changes in climatic means (mean air temperature and annual precipitation), (b) refined model selection based on projected changes in climatic extremes, and (c) final model selection based on past performance. One GCM/ensemble was selected at each corner of four climate extremes (cold/dry, warm/dry, cold/wet, and warm/wet) for RCP4.5 and RCP8.5 in the short-term (2016-2045), mid-century (2036-2065), and end-of-century (2071-2100) periods. After the selection of representative GCMs/ensembles, quantile mapping was applied for bias correction at a finer resolution of 10 km × 10 km. The Soil and Water Assessment Tool (SWAT) hydrological model was used for hydrological modelling, and was calibrated and validated using observed river flow data measured near the headworks (intake) of the Sunsari Morang Irrigation Scheme in the Koshi River. Impacts of climate change on the flow of the Koshi River were projected for the short-term, mid-century, and end-of-century periods considering climate change scenarios RCP4.5 and RCP8.5 using downscaled daily precipitation and temperature data. The Agricultural Production Systems Simulator (APSIM) crop model was selected for crop modelling, and was calibrated and validated using measured field data which included phenological development, biomass yield, and grain yield for the winter wheat crop in the Sunsari Morang Irrigation Scheme command area over two years. Impacts of climate change on the irrigation water demand, biomass yield, and grain yield were predicted for the short-term, mid-century, and end-of-century periods considering climate change scenarios RCP4.5 and RCP8.5, using downscaled daily precipitation and temperature data. In addition, the irrigation demand (mm/cropping period) required to reach potential wheat grain yields under current climate conditions was compared with observed irrigation practices and crop grain yield. The hydraulic capacity of the main canal networks in the Sunsari Morang Irrigation Scheme, in terms of water losses and flow carrying capacity, were assessed using the Personal Computer Stormwater Management Model (PCSWMM) hydraulic model, which was calibrated and validated using measured canal characteristics, discharge, flow velocity, and water depth data. Information on daily water availability at the headwork of Sunsari Morang Irrigation Scheme in the Koshi River, drawn from hydrological assessments, was used to estimate water intakes into the canal network system. Based on irrigation water availability at the headwork, and the amount of irrigation water required for winter wheat crops, (both present and future), the winter wheat crop area coverage and the water carrying capacity of the main canal were assessed. The key innovation of this research is the development of a comprehensive methodology to assess the climate change impacts on the supply and demand sides of irrigation water. The research has demonstrated its effectiveness through its successful application in the Sunsari Morang Irrigation Scheme in the Koshi River of Nepal. The methodology and outcome of the research could be adapted to similar physical-climatic conditions around the world to holistically assess the climate change impacts on both the supply and demand sides of irrigation water. The findings of this research are beneficial to water practitioners, the agricultural community, policymakers, planners, and researchers in Nepal and internationally. The findings on representative General Circulation Models (GCMs) selection for the Koshi River basin could also be used by research and scientific communities. Findings on climate change impacts on precipitation and temperature, and projected Koshi River flows could be used by the National Planning Commission, Nepal and Water and Energy Commission Secretariat, Nepal, for sectoral and water resources project planning, and in formulating water resources policies and basin plans for the Koshi River basin respectively. Findings on climatic changes and their potential implications could be used by the relevant sectors for the development of adaptation strategies, including the National Planning Commission, Nepal. It could also be used by the Department of Water Resources and Irrigation, Nepal, for planning and management of irrigation projects and the expansion of the irrigation command areas. The findings on projected climate change impacts on water resources, irrigation water demand and hydraulic assessment of the irrigation canal network could be used by the Department of Water Resources and Irrigation, Nepal, to manage irrigation projects in the region and by local farmers to increase crop yield in study area. It is also hoped that the challenge of agricultural production for the growing population in the developing world could be addressed with some insights provided by this research, despite the negative impacts of climate change on the irrigation and water resources sector.

Increasing food, feed, fiber, biofuel production on decreasing amounts of arable land while simultaneously enhancing ecosystem services is challenging. Strategic inclusion of winter rye (Secale cereale) for biomass, silage, grain and Kura clover (Trifolium ambiguum) living mulch into existing Midwestern cropping systems may offer alternative economic income for farmers without displacing or reducing yields of primary crops. Research was conducted at the Purdue Water Quality Field Station (WQFS) where net balances of water, carbon, nitrogen, and radiation can be measured, and greenhouse gas (GHG) emissions are monitored. The agronomic performance of a corn-soybean rotation and continuous corn (controls) were compared to novel systems that included the use of rye cover cropping and Kura clover co-cropping. Rye was harvested for biomass/silage at heading immediately followed by corn or soybean planting. Continuous corn receiving 69 kg N ha^-1 was planted into an establishment of Kura clover sod. Controls included these same systems without the rye or clover. GHG samples were taken via the static chamber method and tile-drained water sub-samples were collected, analyzed for nitrate, and load losses calculated. Biomass composition was determined and used to calculate herbage theoretical ethanol (EtOH) yields. Cereal rye did not significantly decrease corn or soybean grain yield. Averaged across years, Kura clover significantly depressed corn grain yields by nearly 70%. Kura clover significantly reduced flow-weighted tile drainage nitrate (NO₃^-) concentrations, however cereal rye did not. Reductions in flow-weighted tile drainage nitrate (NO₃^-) concentrations were found to largely occur during Quarter two (April, May, June). Cover crops did not significantly reduce annual tile drained NO₃^- load losses in most cases, however, they did significantly reduce annual N₂O emissions. Cumulative annual CH₄ emissions were not significantly altered. Annual CO₂emissions were higher after the introduction of Kura clover and not significantly altered following the introduction of cereal rye. Averaged across years, theoretical ethanol yields in the Kura clover system produced 2,752 L EtOH ha^-1, whereas EtOH production in cereal rye systems ranged from 3,245 to 4,210 L EtOH ha^-1. Theoretical ethanol yields of continuous corn and rotational controls ranged from 2,982 to 3505 L EtOH ha^-1 for these same systems without the cereal rye of Kura clover. These data suggest that a multipurpose approach to cover crop inclusion can provide both environmental and economic advantages worthy of consideration.

Organic farming is increasingly viewed as a plausible production system for sustainable agriculture for smallholder farmers. However, there is not enough scientific evidence and knowledge to advocate certified organic farming for African smallholder farmers who face several constraints related to production, storage and marketing. The potential for organic farming for smallholder farmers, faced by these constraints, is not clearly defined. As a result, this study set out to evaluate the production potential of organic agriculture among three smallholder farmer groups. Production questions were used to investigate and evaluate the potential for organic agriculture among three smallholder farmer groups and constituted the following subproblems: · What crops can be grown in the three study areas, based on climatic data ? · Do farmers concur that these are the most suitable potential organic crops? · How useful do the farmers find the decision making tool? · What constraints threaten commercial production of the identified crops for these farmers? Participatory methodologies that included the use of Force Field Analysis, discussions and workshops were used to identify organic production constraints related to production decisions. Farmers faced constraints related to finance, capacity enhancement, technical knowledge, fencing, irrigation, and a lack of, or inappropriately trained extension officers. As a response to identified production constraints, a decision support tool was developed. Natural resource data, including climatic and agronomic data, was used to create a specially calibrated Microsoft Excel spreadsheet interface that functions as an empirical organic production decision support tool for organic and aspirant organic smallholder farmers, by providing answers for farmer-prioritised production constraints. A list of potential crops for each of the three study areas was subjected to a series of checks against suitability for climate and disease conditions and nutrient requirements. A limited supply of manure, to meet the enormously high requirements for organic production in the poor soils of these areas, is the major constraint to exclusive organic production and renders certified organic production difficult and unsustainable. Farmers disagreed with some of the crops on the list, arguing that familiar crops were rejected by the model, but they were excited by the prospects for production of “new” crops suggested as suitable by the decision support tool, but not yet grown in the study areas. End users welcomed the model and expressed the opinion that it would be useful in decision making related to organic crop production. The study concludes that, although a number of agronomically-suitable crops can grow in the study areas, organic production is restricted by rather high manure requirements, lack of compost making skills, lack of knowledge on natural pest and disease control and poorly nourished soils, leading to poor yields. The rainy season creates a disease-supporting environment, rendering organic farming risky for rain-fed smallholder farming. Risk in certified organic farming for smallholders was further exacerbated by a hardly inconducive policy environment that low literacy levels exist amongst farmers. This study is innovative for three reasons. First, farmers were true participants and drivers of the research. Second, trans-disciplinary expert seminars were attended by experts from different disciplines who critiqued the conceptualisation, design, and implementation of the study. Third, the development of a practical decision-support tool shows innovation towards solving complex smallholder farmers decisions. If organic farming is to be promoted, commitment by government is needed in order to establish policy and legislation on organic farming to direct and govern training, information provision and marketing. Intensive training and knowledge building of organic production for smallholder farmers and extension officers is critical. There are also agroecological risks associated with organic farming for smallholder farmers. Recommendations for future research include comparison between organic agriculture and conventional agriculture, where sustainability of certified organic farming and economic viability can be conducted in the South African context. Improvement of the decision making tool will require involving information technology specialists so that the tool can be installed in community centres, extension offices and other accessible places for farmers and others.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.