1,720,955 research outputs found
Towards sustainable agricultural land use in Nepal under climate change: The role of efficient irrigation and fertilizer application
No full textThe increase in global food demand is expected to rise by 35% to 56% from 2010 to 2050, which poses a significant challenge for humanity, particularly in the face of a growing population and climate change. Achieving a balance between meeting, this increased demand for food and feed while ensuring sustainable agricultural systems without encroaching on natural ecosystems and safeguarding scarce natural resources such as water is imperative, particularly in light of projected climate change impacts. A considerable part of the world’s agricultural land is currently not realizing its maximum productivity potential. Nepal is among these regions, where inadequate mineral nutrient use, insufficient management options, and inadequate irrigation water supply significantly contribute to the existing yield gaps.
Enhancing food production to achieve food self-sufficiency is the foremost objective in Nepal. Nepal’s Ministry of Agriculture Development had proposed an Agriculture Development Strategy to transform the agricultural sector, which focuses on raising agricultural productivity through efficient fertilizer use, expanding irrigated areas, improving irrigation efficiency, and promoting efficient and sustainable farming practices.
In this dissertation, I endeavored to model some of the objectives outlined in the Agriculture development strategy and investigate current and future agriculture potential on a national scale in Nepal. Specifically, the primary goal of this thesis is to analyze the current yield gap of major cereal crops in Nepal, proposing ways to narrow it down, and then evaluate different scenarios of the sustainable utilization of water and mineral nutrients in the future, considering the impacts of climate change on agricultural croplands. To achieve this objective, the study is structured into three main chapters: (1) Model-based yield gap assessment in Nepal’s diverse agricultural landscape, (2) Effect of irrigation canal conveyance efficiency enhancement on crop productivity under climate change in Nepal and, (3) Assessment of the effect of Alternate Wetting and Drying (AWD) and Continuous flooding (CF) in rice production in Terai Nepal.
First, I quantified the gap between current and potentially attainable yields in Nepal and determined the additional amount of fertilizer and irrigation required to bridge this gap. I then assessed the country’s potential to achieve self-sufficiency in cereal food production. The findings suggest that Nepal could attain food self-sufficiency if there is consistent and effective management of mineral nutrients and water supply. Results showed considerable average yield gaps in Nepal which are 3.0 t/ha (wheat), 2.7 t/ha (rice), 2.9 t/ha (maize), 0.4 t/ha (barley), and 0.5 t/ha (millet). The pathways to narrow down this yield gap are by efficiently using additional irrigation water and fertilizer application. Cereal yields can be improved by 0.4 to 1.3 t/ha (rice), 0.1 to 2.3 t/ha (wheat), 1.6 to 1.9 t/ha (maize), 0.1 to 0.4 t/ha (millet), and 0.1 to 0.3 t/ha (barley) with irrigation water and fertilizer application, respectively.
I then assessed the potential impact of expanding irrigated areas in the near future (2023-2050) and far future (2075-2100) periods with three canal conveyance efficiency (30%, 50% and 70%) on the productivity of rice, maize, and wheat under three climate change scenarios (SSP1-2.6, SSP3-7.0, SSP5-8.5), utilizing three bias-adjusted Coupled Model Intercomparison Project based general circulation models (GFDL-ESM4, MPI-ESM1-2-HR, and IPSL-CM6A-LR). Results indicated that increasing canal conveyance efficiency to 30%, coupled with expanded irrigated areas and adjusted fertilization rates, could boost yields up to 3t/ha per hectare across all three crops at the national level in the future. The results also indicated that in future, improving canal conveyance efficiency from 30% to 50% increases yields up to 0.6 t/ha for maize and up to 1.2 t/ha for rice, while further improvement to 70% results in increases of up to 1.2 t/ha for maize and 2.1 t/ha for rice in the Terai region. The benefits of improved canal conveyance efficiency vary by location, with the subtropical Terai region experiencing the most and the mountain regions showing the least. I found that achieving canal conveyance efficiencies of 70% in the Terai region, 50% in the hill region, and 30% in the mountains is sufficient to enhance crop yields.
Finally, I found that adopting the climate-friendly water-conserving measure of Alternate Wetting and Drying over the conventional Continuous Flooding method for rice in the Terai region in the near future (2023 – 2050) has resulted in significant improvements across multiple aspects. First, rice yields increased by 0.2 to 1.4 t/ha after implementing alternate wetting and drying practices. Additionally, irrigation amounts were reduced by 350 to 450mm under the Alternate Wetting and Drying method, which suggests improved water use. In addition, there was a considerable decrease in methane emissions by 23 to 27 Gg CH4 yr-1 in the Terai region with the Alternate Wetting and Drying practice, demonstrating this approach's environmental benefits.
In summary, this doctoral thesis aims to contribute to the ongoing discourse of feeding a growing national population through domestic production, taking into account food self-sufficiency and food security in Nepal, a low-input use developing country with rugged terrain and multiple agro-climatic zones. The pathways to achieve this food self-sufficiency and food security in a sustainable manner were analyzed. These pathways encompass, first, the closing yield gaps of major cereal crops of Nepal through the efficient utilization of fertilizers and water; second, expansion of irrigated areas and enhancement of canal conveyance efficiency; and third, adoption of climate-smart adaptation measure alternate wetting and drying methods in rice cultivation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effect of irrigation canal conveyance efficiency enhancement on crop productivity under climate change in Nepal
Get PDF<jats:title>Abstract</jats:title><jats:p>Nepal is expanding its irrigation facilities as an adaptive measure to climate change; however, the current canal conveyance efficiency (CCE) is low with significant water losses. In this study, we assess the potential impact of increasing CCE on the productivity of rice, maize, and wheat under different climate change scenarios (SSP1-2.6, SSP3-7.0, and SSP5-8.5), utilizing three bias-adjusted general circulation models. The study simulates potential yields at ecoregion levels for two periods: near future (2023 to 2050) and end-century (2075 to 2100). Management scenarios include the following: (1) business as usual, (2) CCE at 30%, (3) CCE at 50%, and (4) CCE at 70%. The results indicate that increasing CCE to 30%, coupled with expanded irrigated areas and adjusted fertilization rates, could boost yields by three tons per hectare across all three crops at the national level. Further increasing CCE to 50% could yield additional increases of up to 0.6 t/ha of maize and 1.2 t/ha of rice in the terai region. A CCE of 70% results in further increases of up to 2.1 t/ha of rice and 1.2 t/ha of maize. The benefits of improved CCE vary by location, with the subtropical terai region experiencing the most and the mountain regions showing the least. We conclude that there is potential to increase yields by increasing CCE to 70% in the terai region, 50% in the hill region, and 30% in the mountains. Wheat appears to benefit the least from improved CCE. This work highlights efficient irrigation as a reliable adaptive measure for future climate change in Nepal.</jats:p>
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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