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All Subjects: Sustainability
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Sustaining irrigation agriculture for the long-term: lessons on maintaining soil quality from ancient agricultural fields in the Phoenix Basin and on the north coast of Peru

Description

Irrigation agriculture has been heralded as the solution to feeding the world's growing population. To this end, irrigation agriculture is both extensifying and intensifying in arid regions across the world in an effort to create highly productive agricultural systems. Over one third of modern irrigated fields, however, show signs of serious soil degradation, including salinization and waterlogging, which threaten the productivity of these fields and the world's food supply. Surprisingly, little ecological data on agricultural soils have been collected to understand and address these problems. How, then, can expanding and intensifying modern irrigation systems remain agriculturally productive for the long-term? Archaeological case studies can provide critical insight into how irrigated agricultural systems may be sustainable for hundreds, if not thousands, of years. Irrigation systems in Mesopotamia, for example, have been cited consistently as a cautionary tale of the relationship between mismanaged irrigation systems and the collapse of civilizations, but little data expressly link how and why irrigation failed in the past. This dissertation presents much needed ecological data from two different regions of the world - the Phoenix Basin in southern Arizona and the Pampa de Chaparrí on the north coast of Peru - to explore how agricultural soils were affected by long-term irrigation in a variety of social and economic contexts, including the longevity and intensification of irrigation agriculture. Data from soils in prehispanic and historic agricultural fields indicate that despite long-lived and intensive irrigation farming, farmers in both regions created strategies to sustain large populations with irrigation agriculture for hundreds of years. In the Phoenix Basin, Hohokam and O'odham farmers relied on sedimentation from irrigation water to add necessary fine sediments and nutrients to otherwise poor desert soils. Similarly, on the Pampa, farmers relied on sedimentation in localized contexts, but also constructed fields with ridges and furrows to draw detrimental salts away from planting surfaces in the furrows on onto the ridges. These case studies are then compared to failing modern and ancient irrigated systems across the world to understand how the centralization of management may affect the long-term sustainability of irrigation agriculture.

ContributorsStrawhacker, Colleen (Author) / Spielmann, Katherine A. (Thesis advisor) / Hall, Sharon J (Committee member) / Nelson, Margaret C. (Committee member) / Sandor, Jonathan A (Committee member) / Arizona State University (Publisher)

Created2013

Understanding governance dynamics in a social-ecological system: Chitwan community forests and the invasive mile-a-minute weed

Description

Employing an interdisciplinary approach with a grounding in new institutional economics, this dissertation investigates how institutions, as shared rules, norms, and strategies, mediate social-ecological outcomes in a system exposed to a novel threat in the form of a rapidly growing and especially destructive invasive plant, Mikania micrantha (Mikania). I explore whether and how communities (largely part of community forest user groups in the buffer zone of Chitwan National Park in Chitwan, Nepal) collectively act in the face of Mikania invasion. Collective action is vital to successful natural resource governance in a variety of contexts and systems globally. Understanding collective action and the role of institutions is especially important in the face of continued and amplifying global environmental changes impacting social-ecological systems, such as climate change and invasive species. Contributing to efforts to bolster knowledge of the role of collective action and institutions in social-ecological systems, this research first establishes that community forest governance and institutional arrangements are heterogeneous. I subsequently utilize content and institutional analyses to identify and address themes and norms related to Mikania management. The content analysis contributes an empirical study of the influence of trust in collective natural resource management efforts. Using two complementary econometric analyses of survey data from 1235 households, I additionally assess equity in access to community forest resources, an understudied area in the institutional literature, and the factors affecting collective action related to Mikania removal. Finally, an agent-based model of institutional change facilitates the comparison of two perspectives, rational choice and cultural diffusion, of how shared norms and strategies for Mikania management change over time, providing insight into institutional change generally. Results highlight the importance of trust and understanding the de facto, or on-the-ground institutions; the influence of perception on collective action; that integrating equity into institutional analyses may strengthen sustainable resource management efforts; and that rational choice is an unlikely mechanism of institutional change. The mixed-methods approach contributes to a more comprehensive understanding of the role of institutions and collective action in invasive species management and broadly to the scientific understanding of the role of institutions in mediating global environmental changes.

ContributorsSullivan, Abigail (Author) / York, Abigail M (Thesis advisor) / An, Li (Committee member) / Yabiku, Scott T (Committee member) / Hall, Sharon J (Committee member) / Arizona State University (Publisher)

Created2016

Dimensions of Phosphorus Sustainability: Phosphorus Flows in a Rapidly Growing City and Field Tests of Potential Agricultural Prototypes

Description

Phosphorus (P) is a limiting nutrient in ecosystems and is mainly used as fertilizer to grow food. The demand for P is increasing due to the need for increased food supply to support a growing population. However, P is obtained from phosphate rock, a finite resource that takes millions of years to form. These phosphate rock deposits are found in only a few countries. This uneven distribution of phosphate rock leads to a potential imbalance in socio-economic systems, generating food security pressure due to unaffordability of P fertilizer. Thus, the first P-sustainability concern is a stable supply of affordable P fertilizer for agriculture. In addition, improper management of P from field to fork leaves an open end in the global P cycle that results in widespread water pollution. This eutrophication leads to toxic algal blooms and hypoxic “dead zones”. Thus, the second P-sustainability concern involves P pollution from agriculture and cities. This thesis focuses on P flows in a city (Macau as a case study) and on potential strategies for improvements of sustainable P management in city and agriculture. Chapter 2 showed a P-substance-flow analysis for Macau from 1998-2016. Macau is a city with a unique economy build on tourism. The major P flows into Macau were from food, detergent, and sand (for land reclamation). P recovery from wastewater treatment could enhance Macau’s overall P sustainability if the recovered P could be directed towards replacing mined P used to produce food. Chapters 3 and 4 tested a combination of P sustainability management tactics including recycling P from cities and enhancing P-use efficiency (PUE) in agriculture. Algae and biosolids were used as recycled-P fertilizers, and genetically transformed lettuce was used as the a PUE-enhanced crop. This P sustainable system was compared to the conventional agricultural system using commercial fertilizer and the wild type lettuce. Chapters 3 and 4 showed that trying to combine a PUE-enhancement strategy with P recycling did not work well, although organic fertilizers like algae and biosolids may be more beneficial as part of longer-term agricultural practices. This would be a good area for future research.

ContributorsChan, Neng Iong (Author) / Elser, James J (Thesis advisor) / Rittmann, Bruce E. (Thesis advisor) / Grimm, Nancy (Committee member) / Hall, Sharon J (Committee member) / Arizona State University (Publisher)

Created2020