As climate change impacts a growing number of aspects of economic activity, it is becoming ever more vital to understand how these effects will manifest. This work advances the study of the impacts of environmental change. First, I provide a panel analysis at the country level that identifies the effects of dust storms on economic activity in West Africa. I also find some evidence in the agricultural sector to support the finding of damaging effects. Second, I examine the extent to which dust storms and climate shocks affect migration in the same region. While temperatures and precipitation are found to play important roles, dust storms do not appear to have a significant influence. Third, I consider the role of adaptation to climate change in the United States. I build a model that predicts the locations most likely to be used in agriculture in the future, allowing for better forecasting of shifts in the areas used for agricultural production.

Thesis (M.Sc. (Agriculture)) --University of Limpopo (Turfloop Campus), 2008 / A large number of emerging farmers in South Africa is involved in subsistence agriculture as a result of poor resource endowment or due to other constraints. Relatively few agricultural products from emerging farmers reach the formal agricultural market. Livestock production is common among emerging farmers and a large proportion of the national livestock is in the hands of the rural poor. Horticultural crops are generally perishable and require immediate disposal, thus implying that the farmers who produce horticultural crops do so with intention to sell their products. Most studies tend to group farmers regardless of their line of production. Only few studies have attempted to investigate the socioeconomic characteristics of farmers, differentiating the commodities that they produce. The objective of this study is to identify and compare the socioeconomic characteristics that determine the farm income of the emerging livestock farmers and horticultural farmers in South Africa. Such an analysis would allow more targeted policy responses for different groups of emerging farmers. The data used in this study consisted of 202 livestock farmers and 126 horticultural farmers selected through quota sample covering all nine provinces in South Africa. The data were collected by the Development Bank of Southern Africa in 2005. Descriptive Analysis and Discriminant Analysis are applied to determine the factors that matter the most in determining incomes of livestock and horticultural farmers. Farm iv income is used as the dependent variable, and fourteen independent variables were identified. The factors that matter the most in determining livestock farmers’ income are, namely access to finance, farm size, age of the household head, membership to farmer organizations and government support. The factors that matter most in determining horticultural farmer’s income are namely farm size, age of the household head, land type (land ownership), and extension services. The results of this study showed that access to land and age of the household head matter the most to both livestock and horticultural farmers. The study found that poor access to land is one of the major constraints facing emerging farmers in South Africa. Land is also one of the factors that may determine the amount of credit the emerging farmers can obtain and, if farmers produce on communal land, it becomes harder to obtain credit. Memberships to farmer’s organisations, government support and access to finance are characteristics that matter the most to livestock and do not seem to matter that much to horticultural farmers. Farmer organisations often lobby for collective provision of appropriate and needed services for their membership. The services that are often lobbied for are services such as extension, marketing and provision of training to empower women and young people so as to enable them to participate fully in farming activities. The results of this study show that there are differences in socio-economic characteristics that matter the most in determining farm income for livestock and horticulture farmers. v Horticulture farmers should be given much support to improve access to get enough land and training while in livestock farming assistance focus should be on access to finance and support services. vi

Thesis (MSc. (Botany)) -- University of Limpopo, 2015 / Soybean is an important source of high quality protein and oil for both humans and animals, especially in protein formulations for pharmaceutical and nutriceutical use. This crop is adversely affected by both biotic and abiotic stresses impacting on its productivity. Soybean productivity can be improved via techniques such Agrobacterium-mediated genetic transformation. Soybean is recalcitrant and depends on suitable explants from which new shoots can be regenerated and be amenable for transformation. The goal of this study was to produce transgenic soybean plants that are tolerant to drought stress through Agrobacterium tumefaciens-mediated transformation. Multiple shoot induction on double and single coty-node explants, obtained from soybean seedlings derived from seeds germinated in vitro on Murashige and Skoog culture medium supplemented with cytokinins was studied. The effect of different concentrations of benzyladenine (1.57, 2.00 and 4.00 mg/l), and benzyladenine (2.00 mg/l) in combination with kinetin (1.00 mg/l) was tested. The results show that the double coty-node explants produce the highest number of shoots per explant, an average of 7.93 shoots on Murashige and Skoog medium supplemented with 2.00 mg/l benzyladenine. The lowest number being 1.87 shoots obtained from single coty-node explants cultured on Murashige and Skoog medium containing 4.00 mg/l benzyladenine. The single coty-node explants showed lower frequency (10–57%) of shoot induction when compared to the double coty-node explants (50–83%). The suitability of aminoglycoside antibiotics (hygromycin, tetracycline and rifampicin) for efficient elimination of Agrobacterium tumefaciens after co-cultivation was tested using a well agar diffusion assay. Co-culturing double coty-node explants with Agrobacterium containing pTF 101 vector carrying the Oryza cystatin 1 gene resulted in 76.6, 63.3 and 60.0% shoot regeneration on Murashige and Skoog shoot induction media (shoot induction medium 1, shoot induction medium 2 and shoot induction medium 3) containing hygromycin, tetracycline and rifampicin at 500 mg/l respectively. These antibiotics showed the highest zones of inhibition against pTF 101 using the well agar diffusion assay. On the other hand, 85% plant regeneration was obtained during in vivo transformation following Agrobacterium injection into seedlings. These results imply that vi both in vitro and in vivo protocols were suitable for transgenic shoot regeneration and plant establishment since all the plants continued surviving in the presence of 6.00 mg/l glufosinate-ammonium. Future work will focus on screening of transgenic plants using beta-glucuronidase and isolating the protein encoded by the Oryza cystatin 1 gene to further confirm the generation of transformed plants carrying the gene of interest.

Trends in Utah's agriculture and some factors influencing farmer's decisions concerning eight crops produced on irrigated lands in Utah were studied. Trend lines were calculated and compared with statistics of acreages and yields. Simple and multiple regression tests were made. An increasing number of Utah farmers have taken off-farm employment and operate their farms on a part-time basis. Forage and grain crops both adapt readily to part0time farm operations and these crops do not entail the degree of risk involved in the production of most cash crops. Variety improvements have caused some shifting to wheat production. Product prices, costs, weather, government programs, and labor problems were also found to be important factors influencing farmers decisions.

Bibliography: leaves 81-100. Entry of inoculum into a crop and disease development in the crop cannot be prevented because spores are airborne and there is a lack of highly resistant varieties. This makes complete control of chocolate spot unlikely. It should however, be possible to improve current levels of disease control through the integration of the factors identified in the study.

[Typewritten] Includes bibliographical references.

"August 2002" Bibliography: leaves 230-254. Field sites and soils from cropping studies in the mid-north of South Australia were used to address questions of soil responses to lime and the influence of acidifying inputs. The study showed that LMWOAs associated with different stubbles can help to ameliorate toxicity through complexation with A1.

This study describes how farmers manage climate variability in dryland crop production, and aims to contribute to the theory and practice of decision support for managing climate variability. The intent was to study farmer decision making to see how DSS could be used to deliver information and procedures on climate risk to farmers more effectively. The study investigated whether there are significant differences between farmers' subjective distributions of seasonal rainfall and its derivatives (such as crop yield and fallow recharge) and a probability distribution derived from long-term records and simulation models, and whether these differences in risk assessment lead to changes in the optimum decision. Subjective probability distributions of rainfall and its derivatives were collected from farmers and advisers and it was found the overall match between these and long term records and simulation models was close. This study found little evidence to support the role of DSS for routine decision making, but this does not lessen the value of distributions derived from simulation models. Rather, it provides an opportunity for both farmers and scientists to learn. / Doctor of Philosophy (PhD)

Cotton crop condition was assessed from an analysis of multispectral aerial video imagery. Visible-near infrared imagery of two cotton fields was collected towards the end of the 1990 crop. The digital analysis was based on image classification, and the accuracies were assessed using the Kappa coefficient of agreement. The earliest of three images proved to be best for distinguishing plant variety. Vegetation index images were better for estimating potential yield than the original multispectral image; so too were multi-channel images that were transformed using vegetation indices or principal component analysis. The seedbed preparation rig used, the nitrogen application rate and three plant varieties, a weed species and two cotton cultivars, could all be discriminated from the imagery. Accuracies were moderate for the discrimination of plant variety, tillage treatment and nitrogen treatment, and low for the estimation of potential yield.

"August 2002" / Bibliography: leaves 230-254. / [11], 254 leaves : ill. (some col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Field sites and soils from cropping studies in the mid-north of South Australia were used to address questions of soil responses to lime and the influence of acidifying inputs. The study showed that LMWOAs associated with different stubbles can help to ameliorate toxicity through complexation with A1. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 2002