Matching Items (3)
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- All Subjects: Agriculture
- Genre: Masters Thesis
- Creators: Aggarwal, Rimjhim
Description
Phosphorus (P), an essential element for life, is becoming increasingly scarce, and its global management presents a serious challenge. As urban environments dominate the landscape, we need to elucidate how P cycles in urban ecosystems to better understand how cities contribute to — and provide opportunities to solve — problems of P management. The goal of my research was to increase our understanding of urban P cycling in the context of urban resource management through analysis of existing ecological and socio-economic data supplemented with expert interviews in order to facilitate a transition to sustainable P management. Study objectives were to: I) Quantify and map P stocks and flows in the Phoenix metropolitan area and analyze the drivers of spatial distribution and dynamics of P flows; II) examine changes in P-flow dynamics at the urban agricultural interface (UAI), and the drivers of those changes, between 1978 and 2008; III) compare the UAI's average annual P budget to the global agricultural P budget; and IV) explore opportunities for more sustainable P management in Phoenix. Results showed that Phoenix is a sink for P, and that agriculture played a primary role in the dynamics of P cycling. Internal P dynamics at the UAI shifted over the 30-year study period, with alfalfa replacing cotton as the main locus of agricultural P cycling. Results also suggest that the extent of P recycling in Phoenix is proportionally larger than comparable estimates available at the global scale due to the biophysical characteristics of the region and the proximity of various land uses. Uncertainty remains about the effectiveness of current recycling strategies and about best management strategies for the future because we do not have sufficient data to use as basis for evaluation and decision-making. By working in collaboration with practitioners, researchers can overcome some of these data limitations to develop a deeper understanding of the complexities of P dynamics and the range of options available to sustainably manage P. There is also a need to better connect P management with that of other resources, notably water and other nutrients, in order to sustainably manage cities.
ContributorsMetson, Genevieve (Author) / Childers, Daniel (Thesis advisor) / Aggarwal, Rimjhim (Thesis advisor) / Redman, Charles (Committee member) / Arizona State University (Publisher)
Created2011
Description
Haiti has witnessed high deforestation rates in recent decades, caused largely by the fuel needs of a growing population. The resulting soil loss is estimated to have contributed towards a decline in agricultural productivity of 0.5% -1.2% per year since 1997. Recent studies show the potential of biochar use through pyrolysis technology to increase crop yields and improve soil health. However, the appropriateness of this technology in the context of Haiti remains unexplored. The three objectives of this research were to identify agricultural- and fuel-use-related needs and gaps in rural Haitian communities; determine the appropriateness of biochar pyrolyzer technology, used to convert agricultural biomass into a carbon-rich charcoal; and develop an action-oriented plan for use by development organizations, communities, and governmental institutions to increase the likelihood of adoption. Data were collected using participatory rural appraisal techniques involving 30 individual interviews and three focus-group discussions in the villages of Cinquantin and La Boule in the La Coupe region of central Haiti. Topics discussed include agricultural practices and assets, fuel use and needs, technology use and adoption, and social management practices. The Sustainable Livelihoods framework was used to examine the assets of households and the livelihood strategies being employed. Individual and focus group interviews were analyzed to identify specific needs and gaps. E.M. Rogers' Diffusion of Innovations theory was used to develop potential strategies for the introduction of pyrolysis technology. Preliminary results indicate biochar pyrolysis has potential to address agricultural and fuel needs in rural Haiti. Probable early adopters of biochar technology include households that have adopted new agricultural techniques in the past, and those with livestock. Education about biochar, and a variety of pyrolysis technology options from which villagers may select, are important factors in successful adoption of biochar use. A grain mill as an example in one of the study villages provides a model of ownership and use of pyrolysis technology that may increase its likelihood of successful adoption. Additionally, women represent a group that may be well suited to control a new local biochar enterprise, potentially benefiting the community.
ContributorsDelaney, Michael Ryan (Author) / Aggarwal, Rimjhim (Thesis advisor) / Chhetri, Nalini (Committee member) / Henderson, Mark (Committee member) / Arizona State University (Publisher)
Created2011
Description
Alfalfa is a major feed crop widely cultivated in the United States. It is the fourth largest crop in acreage in the US after corn, soybean, and all types of wheat. As of 2003, about 48% of alfalfa was produced in the western US states where alfalfa ranks first, second, or third in crop acreage. Considering that the western US is historically water-scarce and alfalfa is a water-intensive crop, it creates a concern about exacerbating the current water crisis in the US west. Furthermore, the recent increased export of alfalfa from the western US states to China and the United Arab Emirates has fueled the debate over the virtual water content embedded in the crop. In this study, I analyzed changes of cropland systems under the three basic scenarios, using a stylized model with a combination of dynamical, hydrological, and economic elements. The three scenarios are 1) international demands for alfalfa continue to grow (or at least to stay high), 2) deficit irrigation is widely imposed in the dry region, and 3) long-term droughts persist or intensify reducing precipitation. The results of this study sheds light on how distribution of crop areas responds to climatic, economic, and institutional conditions. First, international markets, albeit small compared to domestic markets, provide economic opportunities to increase alfalfa acreage in the dry region. Second, potential water savings from mid-summer deficit irrigation can be used to expand alfalfa production in the dry region. Third, as water becomes scarce, farmers more quickly switch to crops that make more economic use of the limited water.
ContributorsKim, Booyoung (Author) / Muneepeerakul, Rachata (Thesis advisor) / Ruddell, Benjamin (Committee member) / Aggarwal, Rimjhim (Committee member) / Arizona State University (Publisher)
Created2015