Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

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Assessing Organic Farm Nutrient Management

Description
The United States Department of Agriculture provides requirements for a farm operation to become certified organic, but how do these regulations influence nutrient management on organic farms? There is insufficient evidence to show if the current regulations on nutrient sourcing and application are feasible and effective. An online survey was…

The United States Department of Agriculture provides requirements for a farm operation to become certified organic, but how do these regulations influence nutrient management on organic farms? There is insufficient evidence to show if the current regulations on nutrient sourcing and application are feasible and effective. An online survey was administered to owners and operators of organic farms. Survey respondents were offered a free soil test as an incentive to participate and to compare their practices and soil quality. Assessing the current nutrient management under organic regulations provides information to help assess the sustainability of their nutrient management practices. Early data suggest that organic farmers may most often be overapplying and creating legacy sources with this key resource.
ContributorsBonham, Emma Eileen (Author) / Muenich, Rebecca (Thesis advisor) / Zanin, Alaina (Committee member) / Williams, Clinton (Committee member) / Arizona State University (Publisher)
Created2022
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Review of the Quantitative Tradeoffs of Using Organic Residuals in Arid Agriculture

Description
Water reuse and nutrient recovery are long-standing strategies employed in agricultural systems. This is especially true in dry climates where water is scarce, and soils do not commonly contain the nutrients or organic matter to sustain natural crop growth. Agriculture accounts for approximately 70% of all freshwater withdrawals globally. This…

Water reuse and nutrient recovery are long-standing strategies employed in agricultural systems. This is especially true in dry climates where water is scarce, and soils do not commonly contain the nutrients or organic matter to sustain natural crop growth. Agriculture accounts for approximately 70% of all freshwater withdrawals globally. This essential sector of society therefore plays an important role in ensuring water sources are maintained and that the food system can remain resilient to dwindling water resources. The purpose of this research is to quantify the benefits of organic residuals and reclaimed water use in agriculture in arid environments through the development of a systematic review and case study. Data from the systematic review was extracted to be applied to a case study identifying the viability and benefits of organic residuals on arid agriculture. Results show that the organic residuals investigated do have quantitative benefits to agriculture such as improving soil health, reducing the need for conventional fertilizers, and reducing irrigation needs from freshwater sources. Some studies found reclaimed water sources to be of better quality than local freshwater sources due to environmental factors. Biosolids and manure are the most concentrated of the organic residuals, providing nutrient inputs and enhancing long-term soil health. A conceptual model is presented to demonstrate the quantitative benefits of using a reclaimed water source in Pinal County, Arizona on a hypothetical crop of cotton. A goal of the model is to take implied nutrient inputs from reclaimed water sources and quantify them against standard practice of using irrigated groundwater and conventional fertilizers on agricultural operations. Pinal County is an important case study area where farmers are facing cuts to their water resources amid a prolonged drought in the Colorado River Basin. The model shows that a reclaimed water source would be able to offset all freshwater and conventional fertilizer use, but salinity in reclaimed water sources would force a need for additional irrigation in the form of a large leaching fraction. This review combined with the case study demonstrate the potential for nutrient and water reuse, while highlighting potential barriers to address.
ContributorsKrukowski, William Lee (Author) / Muenich, Rebecca (Thesis advisor) / Williams, Clinton (Committee member) / Hamilton, Kerry (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2020