Browsing by Author "Villacis, Alexis H."

Now showing 1 - 7 of 7
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    Climate Change and Its Positive and Negative Impacts on Irrigated Corn Yields in a Region of Colorado (USA)
    Delgado, Jorge A.; D’Adamo, Robert E.; Villacis, Alexis H.; Halvorson, Ardell D.; Stewart, Catherine E.; Alwang, Jeffrey R.; Del Grosso, Stephen J.; Manter, Daniel K.; Floyd, Bradley A. (MDPI, 2024-08-09)
    The future of humanity depends on successfully adapting key cropping systems for food security, such as corn (Zea mays L.), to global climatic changes, including changing air temperatures. We monitored the effects of climate change on harvested yields using long-term research plots that were established in 2001 near Fort Collins, Colorado, and long-term average yields in the region (county). We found that the average temperature for the growing period of the irrigated corn (May to September) has increased at a rate of 0.023 °C yr−1, going from 16.5 °C in 1900 to 19.2 °C in 2019 (p < 0.001), but precipitation did not change (p = 0.897). Average minimum (p < 0.001) temperatures were positive predictors of yields. This response to temperature depended on N fertilizer rates, with the greatest response at intermediate fertilizer rates. Maximum (p < 0.05) temperatures and growing degree days (GDD; p < 0.01) were also positive predictors of yields. We propose that the yield increases with higher temperatures observed here are likely only applicable to irrigated corn and that irrigation is a good climate change mitigation and adaptation practice. However, since pan evaporation significantly increased from 1949 to 2019 (p < 0.001), the region’s dryland corn yields are expected to decrease in the future from heat and water stress associated with increasing temperatures and no increases in precipitation. This study shows that increases in GDD and the minimum temperatures that are contributing to a changing climate in the area are important parameters that are contributing to higher yields in irrigated systems in this region.
  • Credence attributes and opportunities: a cautionary tale of yerba mate in Paraguay
    Alwang, Jeffrey R.; Villacis, Alexis H.; Barrera, Victor (Emerald, 2022-08-02)
    Purpose: This study explores the determinants of growth of credence-based exports of yerba mate from Paraguay, potential for increased export growth, and the fragility of the credence-based export model. Much of the growth in value of yerba mate exports from Paraguay is due to positioning of the good within the universe of products where consumption is driven by perceptions of sustainable production and health benefits to consumers. Credence claims for yerba mate—benefits to indigenous producing communities, environmental sustainability under certain production processes, healthful alternatives to energy drinks—are now widely known, but the growth of this awareness came via a new entrepreneurial strategy of a single firm. Design/methodology/approach: Primary information was collected through interviews of actors in the Paraguayan yerba mate value chain during spring/summer 2020. These included representatives from three exporting companies, processors, public institutions and indigenous producers. Findings: The Paraguayan yerba mate export boom was stimulated through the careful cultivation of an image of healthful consumption and sustainable production processes. The cost of this cultivation was borne mainly by a single firm. Findings suggest that future marketing efforts will need to reinforce credence claims, highlighting the benefits to indigenous producers. Research limitations/implications: This case study explores the determinants of growth of credence-based exports of yerba mate from Paraguay, potential for increased growth, and the fragility of the credence-based model. Originality/value: Findings are supported by field interviews with value chain participants and detailed analysis of extant data. The paper is the first to discuss the fragility of relying on credence attributes for long-term demand growth.
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    Empirical Studies in Production Economics and International Agricultural Development Issues
    Villacis, Alexis H. (Virginia Tech, 2020-07-16)
    This dissertation is composed of two manuscripts in Production Economics and two manuscripts in International Agricultural Development. The first two manuscripts focus on production economics, and both are an exploration of nitrogen use and its impact on continuous corn production and profitability in Colorado. The first manuscript titled "Switching Regression Stochastic Plateau Production Functions––A Comparison of Alternative Specifications" proposes an alternative approach for estimating crop yield response functions using a frequentist approach. The second manuscript titled "Profitability Effects of Different Tillage Systems in Continuous Corn Rotations" explores the interaction between different tillage systems and nitrogen fertilization in irrigated continuous corn production in northeastern Colorado. We find that strip tillage is better suited for continuous corn production under the agro-climatic conditions in northeastern Colorado. The third and fourth manuscripts focus on international agricultural development and analyze the role of factors that influence the agricultural development of small-holder farmers in Ecuador, namely, markets, food value chains, risk preferences, and risk perceptions. The third manuscript titled "Does the Use of Specialty Varieties and Post-Harvest Practices Benefit Farmers? Cocoa Value Chains in Ecuador" analyzes the impact of the use of specialty cocoa varieties on small-scale farmers' income. It finds that the use of specialty cocoa varieties has a low impact on small-scale cocoa producers' income, and that post-harvest practices may lead to substantial price responses irrespective of the type of cocoa grown. Finally, the fourth manuscript titled "Linking Risk Preferences and Risk Perceptions of Climate Change Using Prospect Theory" explores how farmers' risk preferences correlate with their perceptions of climate risk. It finds that farmers that behave in accordance to the assumptions of prospect theory are more likely to perceive greater risks from climate change, that is, they are more likely to perceive the risks associated with climate change as being more threatening at a personal level. Since risk perception is a necessary prerequisite for adaptation, the results presented in this manuscript, have important policy implications for process of adoption of new technologies aimed at mitigating effects of climate change.
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    Estimating Economically Optimal Levels of Nitrogen Fertilizer in No-Tillage Continuous Corn
    Villacis, Alexis H.; Ramsey, A. Ford; Delgado, Jorge A.; Alwang, Jeffrey R. (2020-11)
    Stochastic plateau production functions provide improved fertilizer recommendations based on multi-year agronomic experiments where weather and other stochastic variables change over time. This research assesses the profitability of no-tillage corn production in northeastern Colorado and determines economically optimal nitrogen fertilizer rates. It also proposes an alternative parameterization of the linear response stochastic plateau model which provides a robustness check against traditional parameterizations. Results show the current use of nitrogen fertilizer in the area exceeds estimated economically optimal levels. This suggests that a reduction in nitrogen use could increase expected profits and simultaneously reduce environmental costs.
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    An Investigation of Institutional, Technological and Economic Conditions in the Markets for Blackberry, Cocoa, and Dragon Fruit in Ecuador, and Yerba Mate in Paraguay
    Alwang, Jeffrey R.; Villacis, Alexis H.; Barrera, Victor H. (2020-07-08)
    Presentation of research progress to multinational research team led by the Interamerican Development Bank.
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    Long-Term Effects of Nitrogen and Tillage on Yields and Nitrogen Use Efficiency in Irrigated Corn
    Delgado, Jorge A.; D’Adamo, Robert E.; Villacis, Alexis H.; Halvorson, Ardell D.; Stewart, Catherine E.; Floyd, Bradley A.; Del Grosso, Stephen J.; Manter, Daniel K.; Alwang, Jeffrey R. (MDPI, 2024-10-07)
    By tonnage, corn (Zea mays L.) is the #1 crop produced globally, and recent research has suggested that no-till (NT) systems can lead to reduced yields of this important crop. Additionally, there is a lack of long-term data about the effects of tillage and N management on cropping systems. Corn is the most nitrogen (N)-fertilized crop in the USA, and N losses to the environment contribute to significant impacts on air and water quality. We conducted long-term studies on conventional tillage (CT) and conservation tillage systems, such as strip tillage (ST) and NT, under different N rates. We found that immediately after conversion to NT, yields from NT were significantly lower than yields from CT (p < 0.1), but after five years of NT, the NT yields were 1.5% higher than the CT yields (p < 0.1). Initially, the NT yields were lower than the ST (p < 0.01), but after seven years of NT, the NT yields were comparable to ST grain yields. Although the total aboveground N uptake with NT immediately after conversion to NT was lower than with CT and ST, these differences were not significant in the long run. The nitrogen use efficiency (NUE) with NT increased over time. The present work highlights the importance of long-term research for determining the cumulative impacts of best management practices such as NT. We found that NT becomes a more viable practice after five or seven years of implementation, demonstrating the high importance of long-term research.
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    Potential use of cover crops for soil and water conservation, nutrient management, and climate change adaptation across the tropics
    Delgado, Jorge A.; Barrera Mosquera, Victor H.; Alwang, Jeffrey R.; Villacis, Alexis H.; Cartagena Ayala, Yamil E.; Neer, Donna; Monar, Carlos; Escudero López, Luis O. (Elsevier, 2021-01-01)
    One of the greatest challenges in the 21st century is the question of how humanity will adapt to a changing climate to continue producing food at the production levels that will be necessary to feed an increasing global population while conserving soil and water resources. While there are political, social and economic factors that impact agricultural development, this paper will not be focusing on those factors, instead focusing on the potential use of cover crops as a nutrient management tool, a soil and water conservation practice, and a good approach to adapting to a changing climate. The potential of using cover crops for climate change adaptation and mitigation will be reviewed. Cover crops are a key tool that could contribute to increased yields, conservation of surface and groundwater quality, reduced erosion potential, sequestration of atmospheric carbon (C), and improved soil quality and health across the tropics. However, there are a lot of research gaps, and there is a need for additional research about the potential use of cover crops for soil, human, and animal health, as well as a need for an open-access data information system about research on cover crops in the tropics. While cover crops show a lot of promise, they are not a silver bullet, and in some circumstances, they can also contribute to reduced yields. We evaluated the use of cover crops and we ranked the different ways that cover crops can contribute to climate change adaptation, on a scale ranging from very low potential to contribute to climate change adaptation to very high potential. For example, cover crops have very high potential to reduce erosion generated by a changing climate in humid systems. On average, cover crops appear to be a good practice for climate change adaptation and mitigation across the tropics, and nutrient managers, agronomists, and soil and water conservation practitioners could add them to their management toolbox for different regions of the tropics. The 4 Rs of cover crops should be applied when using this tool (the right cover crop, the right timing of placement, the right timing of killing, and the right management).