Thesis (Ph. D.)--University of Hawaii (Honolulu), 2000. / Includes bibliographical references (leaves 137-148).

Contemporary global agriculture has been undergoing transition towards different pathways. In developed countries, a shift from productivist agriculture to multifunctional agriculture has begun since the 1980s (Wilson, 2007). In the developing world, agricultural modernisation is still the primary strategy for agricultural development, and driven by urbanisation and industrialisation, deagrarianisation of rural society has been widely identified (Bryceson, 1996; Rigg, 2006a). As the largest developing country in the world, China embarked on market reform three decades ago and has ever since experienced dramatic socio-economic transition towards modernisation, industrialisation and urbanisation. Significant levels of academic attention have focused on empirically identifying economic and policy drivers of Chinese agricultural production from a structuralist standpoint, largely neglecting the agency of smallholders and sociocultural factors. To address the resulting literature gap, this thesis adopts an approach that combines political economy and cultural analysis through an in-depth case study of a rural community in southwest China. A multi-methods approach is used to collect data, including questionnaires, in-depth interviews, focus groups, participant observation and the analysis of secondary data. The results suggest that Chinese smallholder agriculture has been dramatically transformed by an array of socio-economic forces. The “intensive, sustainable, diverse” Chinese smallholder agriculture which Netting (1993) portrayed, has been progressively shifted towards extensive, unsustainable and less diverse pathways. It suggests that the “perfunctory agriculture” performed by Chinese smallholders is the outcome of interactions and negotiations between various political, socio-economic and institutional constraints and farmers’ agency. Another key finding is that moving out of agriculture is becoming the norm in Chinese rural society. Most smallholders show willingness to rent out agricultural land and to enter into a capitalist relationship with employees, rather than primarily being cultivators of their land. Land transfer markets have become increasingly buoyant at the local level, and large-scale capitalist agriculture seems to be the desired future of Chinese smallholder agriculture for both the Chinese government and smallholders. Besides, based on the case of Hu Village, this thesis discusses the convergences and divergences between the road of Chinese agricultural development and that of developed countries and other emerging BRIC economies. Lastly, based on the findings of this research, four policy implications are proposed including sponsoring agricultural mutual aid groups, strengthening agricultural extension services, enhancing farmers’ negotiation power through laws, and initiating comprehensive socio-economic reforms to facilitate farmers’ pursuit of non-farm employments.

Thesis (M.Sc. (Statistics )) -- University of Limpopo, 2021 / Temperature extremes have a crucial impact on agricultural, economic, health and energy sectors due to the occurrence of climate extreme events such as heat waves and cold waves. Limpopo province is among the hottest provinces of South Africa and experiences little rainfall which affect the water availabil ity, food production and biodiversity. In the Limpopo province, temperature extremes are expected to become more frequent as a result of climate change. The aim of this study was to model temperature extremes in the Limpopo province of South Africa using extreme value theory (EVT). The stationarity of the data was tested using augmented Dickey-Fuller (ADF), Phillips-Peron (PP) and Kwiatkowski-Phillips-Schmit-Shin (KPSS). Four candidate parent distri butions: normal, log-normal, gamma and Weibull distributions, were fitted to the average monthly maximum and minimum daily temperatures. Prior to the selection of the parent distributions, the data set at each station was subjected to normality test using the Shapiro-Wilk (SW) and Jarque-Bera (JB) tests. The stationarity and normality tests revealed that the maximum and minimum temperature data series at all the stations are neither stationary nor normally distributed. Akaike information criterion (AIC) and Bayesian information cri terion (BIC) were used to select the best fitting distribution at a particular site. The findings revealed that both maximum and minimum temperatures series at all the stations belong to the Weibull domain of attraction. The findings from the Mann-Kendall (M-K) test and time series plots trend analyses showed that there is a monotonic downward and upward long-term trend in minimum and maximum temperature data, respectively. Two fundamental approaches of EVT, block maxima and peaks-over-threshold (POT), were used in this dissertation. The generalised extreme value (GEV), generalised Pareto (GP) and Poisson point process distributions were fitted to the data set for each station. In order to account for climate change impact, non-stationary models were considered with Seasonal Oscillation Index (SOI) as covariates of the parameters of the GEV distribution. The findings revealed that both the maximum and minimum temperature data can be modelled by the Weibull family of distribution. The EVT return level analysis findings of above 400C for maximum temperature suggests impending heat waves and droughts in the Limpopo province. The bivariate conditional extremes ap proach with a time-varying threshold was used. The findings revealed both significant positive and negative extremal dependence in some pairs of meteo rological stations. The findings of this study play an important role in revealing information useful to meteorologists, climatologists, agriculturalists and plan ners in the energy sector where temperature extremes play an important role. The scientific contribution of this study was to reduce the risk and impact of temperature extremes on agricultural, energy and health sectors in the Limpopo province. An understanding of temperature extremes will help gov ernment and other stakeholders to formulate mitigation strategies that will minimise the negative impact resulting from temperature extremes in the Limpopo province. Among the major contributions of the study was the use of a pe nalised cubic smoothing spline to perform a nonlinear detrending of the tem perature data, before fitting bivariate time-varying threshold excess models based on Laplace margins, to capture the climate change effects in the data. Future studies may consider exploring the use of extreme value copulas, as well as spatio-temporal dependence between temperature extremes using the conditional extremes model of Heffernan and Tawn (2004). / DST National Research Foundation (NRF)

Dagens samhälle är fullt av utmaningar vad gäller hållbarhet. En av de viktigaste frågeställningarna är hur mänskligheten kan tänka om jordbruket för att anpassa sig till den förväntade ökningen i efterfrågan på mat, och samtidigt göra jordbruket mer miljövänligt. Ett tänkbart steg mot mer hållbarhet inom jordbruket är hydroponi. Ändå står hydroponiska system inför sina egna hållbarhetsproblem; ett av problemen är de konventionella substraten som används. De nuvarande konventionella substraten härrör ofta från torv, stenull, perlit och kokosfibrer. Det finns dock möjligheter att implementera industriella symbiotiska nätverk i vilka en sektors avfall är en annans resurs, detta skulle kunna bidra till en minskning av miljöpåverkan jämfört med de konventionella substraten.  Syftet med projektet är att undersöka drivkrafter och hinder som finns för att förbättra hydroponiska stadsodlingars miljöprestanda gällande odlingssubstrat, genom att använda recirkulerade avfallsströmmar från närliggande kommersiella och kommunala verksamheter i stället för konventionella odlingssubstrat. I detta projekt intervjuades tre företag som odlar hydroponiskt i Stockholm för att ytterligare förstå kritiska egenskaper hos substraten, och vilka faktorer som realistiskt måste beaktas när man undersöker brukandet av urbana avfallsströmmar i motsats till konventionella substrat. Detta följs av en litteraturgenomgång som fokuserar på egenskaperna hos både konventionella substrat och de avfallsbaserade substraten. Genom forskningen blev det uppenbart att recirkulering av avfallsströmmar är ett genomförbart alternativ inom hydroponi, och har potential att minska miljöpåverkan från substraten i branschen. Det krävs dock utan tvekan ytterligare forskning på området. Potential för mellanhänder mellan den avfallsproducerande aktören och de hydroponiska odlingarna är ett nästa avgörande steg i utvecklingen av hållbara odlingssubstrat, men för lite forskning finns i dagsläget vilket begränsar möjligheterna inom området. / Today’s society is riddled with challenges regarding sustainability. One of the main concerns is how humanity can rethink farming in order to adapt to the projected demand for food in the near future, whilst also making farming more environmentally friendly. A possible step towards the sustainability of farming is hydroponics. Even so, current hydroponic systems are facing their own sustainability issues; one of which is the growing media used. The current, conventional growing media is often derived from peat, rock wool, perlite, and coconut coir. There are, however, opportunities to implement industrial symbiotic networks in which one processes waste can be used as another’s resource, this would contribute to a reduction in environmental impact compared to the conventional growing mediums.  The aim of this project is to examine the possibilities and barriers that exist regarding the improvement of environmental performance of growing media in hydroponics through the recirculation of urban waste streams from nearby commercial and municipal operations instead of using conventional growing media. In this project three hydroponic farming companies in Stockholm were interviewed to further understand the competition factor of growing mediums, and what factors realistically need to be accounted for when looking into the usage of urban waste streams as opposed to conventional growing media. This is followed by a literature review focusing on the characteristics of both conventional growing media and waste stream derived growing media. It became apparent through the research that recirculating waste streams is a feasible option within hydroponics, and has potential to reduce the environmental impact of growing media in the industry. However, further research is undoubtedly required in the field. Areas such as potential for middlemen between the waste producing actor and hydroponic farms are the next feasible step in the development of sustainable growing media, yet little to no research has currently been done on the matter.