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			Ordenar por:  Relevância Autor Título Ano Registros recuperados: 4.955 Primeira ... 3 4 5 6 7 8 9 10 11 ... Última A DYNAMIC ANALYSIS OF WATER SAVINGS FROM ADVANCED IRRIGATION TECHNOLOGY AgEcon Hornbaker, Robert H.; Mapp, Harry P., Jr.. A computerized grain sorghum plant growth model is combined with recursive programming to analyze the potential irrigation water savings from adopting irrigation scheduling and low pressure center pivot irrigation technology. Results indicate that irrigation pumping can be reduced with increased yields and net returns by adopting low energy precision application (LEPA) irrigation systems. Variations in input and output prices affect optimal irrigation quantities for low pressure irrigation systems less than for high pressure systems. Tipo: Journal Article Palavras-chave: Crop Production/Industries. Ano: 1988 URL: http://purl.umn.edu/32113 A Dynamic Decision Model of Technology Adoption under Uncertainty: Case of Herbicide-Resistant Rice AgEcon Annou, Mamane Malam; Wailes, Eric J.; Thomsen, Michael R.. Herbicide-resistant (HR) rice technology is a potential tool for control of red rice in commercial rice production. Using an ex ante mathematical programming framework, this research presents an empirical analysis of HR rice technology adoption under uncertainty. The analysis accounts for stochastic germination of red rice and sheath blight to model a profit maximization problem of crop rotation among HR rice, regular rice, and soybeans. The results demonstrate that risk attitudes and technology efficiency determine adoption rates and optimal rotation patterns. Tipo: Journal Article Palavras-chave: Biotechnology; Herbicide resistance; Mathematical programming; Profit maximization; Rice; Risk; Rotation; Technology; Adoption; Crop Production/Industries; Production Economics; Research and Development/Tech Change/Emerging Technologies; Q16; Q18; O33; C61. Ano: 2005 URL: http://purl.umn.edu/43724 A DYNAMIC INVESTMENT MODEL FOR TREE CROP AGRICULTURE AgEcon Ajobo, Owolabi. The objective of this paper is to develop a dynamic model that may be useful in the analysis of investment in long term tree crop agriculture. The model is based on linear programming as modified by fixed assets theory. The starting point is the Heady-Loftsgard dynamic linear programming model restated in a stochastic form and imbedded in a decision theoretic construct to give a stochastic mixed integer programming model. The paper goes into a discussion of problems associated with agricultural data collection in Nigeria-on the conviction that specific use of any model can only come after the data problem has been reasonably solved. Tipo: Thesis or Dissertation Palavras-chave: Crop Production/Industries. Ano: 1972 URL: http://purl.umn.edu/11266 A dynamic model of oligopoly in the coffee export market AgEcon Karp, Larry S.; Perloff, Jeffrey M.. A linear-quadratic, dynamic feedback oligopoly model that nests various market structures is used to estimate the degree of competitiveness and the adjustment paths of the two largest coffee exporters, Brazil and Colombia. Their estimated behavior is relatively competitive. This subgame perfect dynamic model is-compared to a standard static oligopoly model and the open-loop model (the dynamic generalization of the standard static model). Both classical and Bayesian tests of open-loop and feedback dynamic models are reported. Tipo: Working or Discussion Paper Palavras-chave: Export marketing; Mathematical models; International Relations/Trade; Crop Production/Industries. Ano: 1990 URL: http://purl.umn.edu/47250 A Dynamic Nutrient Carryover Model for Pastoral Soils and its Application to Optimising Fertiliser Allocation to Several Blocks with a Cost Constraint AgEcon Woodward, Simon J.R.. A dynamical model of soil phosphorus carryover in grazed pasture provides the basis for bioeconomic optimization of fertiliser rates. A linear constraint is introduced to optimise the allocation of limited funds to fertiliser on several farm blocks, each of which represents a different land and/or stock class. The optimal constrained maintenance application of fertiliser to each block is calculated, and an heuristic approach to this equilibrium is suggested. In some cases this involves withholding of fertiliser from unresponsive blocks. The dynamical model and economic optimisation method have been implemented in a commercial fertiliser planning decision support tool Outlook. Tipo: Journal Article Palavras-chave: Crop Production/Industries. Ano: 1996 URL: http://purl.umn.edu/12297 A Dynamic Optimal Crop Rotation Model in Acreage Response AgEcon Cai, Ruohong; Bergstrom, John C.; Mullen, Jeffrey D.; Wetzstein, Michael E.. This paper presents a dynamic crop rotation model that shows how crop yield and price volatility could impact crop mix and acreage response under crop rotation considerations. Specifically, a discrete Markov decision model is utilized to optimize producers’ crop rotation decision within a finite horizon. By maximizing net present value of expected current and future profits, a modified Bellman equation helps develop optimum planting decisions. This model is capable of simulating crop rotations with different lengths and structures. Specifically, the corn-soybeans rotations were simulated using the crop rotation model. Tipo: Working or Discussion Paper Palavras-chave: Crop rotation; Acreage response; Bellman equation; Crop Production/Industries; Research Methods/ Statistical Methods. Ano: 2011 URL: http://purl.umn.edu/103949 A Dynamic Optimisation Model of Weed Control AgEcon Jones, Randall E.; Cacho, Oscar J.. It is argued in this paper that static approaches to weed management, where the benefits and costs are only considered within a single season, are inappropriate for assessing the economic benefits of weed control technologies. There are carryover effects from weed management as weeds that escape control in one season may reproduce and replenish weed populations in following seasons. Consequently, it is appropriate to view weed control in the context of a resource management problem where the goal is to determine the optimal inter-temporal level of weed control that maximises economic benefits over some pre-determined period of time. A dynamic optimisation model for weed control is presented. Using the tools of comparative static analysis and Pontryagin's... Tipo: Presentation Palavras-chave: Crop Production/Industries. Ano: 2000 URL: http://purl.umn.edu/123685 A Dynamic Programming Approach to the Economic Control of Weed and Disease Infestations in Wheat AgEcon Fisher, Brian S.; Lee, R.R.. Weeds and fungal diseases cause significant losses to grain crops in Australia. In many cases cultural methods of control are effective. However, it is often difficult for farm decision-makers to select the optimum crop rotation, from an economic point of view, given the technical constraints they face. A decision to plant a particular crop will have implications for both current and future profitability because the current decision will alter the constraints faced by the decision-maker in subsequent periods. Dynamic programming is used to solve the rotation problem faced by grain growers in north-western New South Wales in areas where the weed, wild oats (A vena falua or A vena ludoviciana), and the disease, crown rot (Fusarium graminearum Group I), have... Tipo: Journal Article Palavras-chave: Crop Production/Industries. Ano: 1981 URL: http://purl.umn.edu/12237 A EVOLUÇÃO DA INDÚSTRIA DE AGROTÓXICOS NO BRASIL DE 2001 A 2007: A EXPANSÃO DA AGRICULTURA E AS MODIFICAÇÕES NA LEI DE AGROTÓXICOS AgEcon Terra, Fabio Henrique Bittes; Pelaez, Victor Manoel. Entre os anos 2001/2007, a agricultura nacional cresceu a taxas extraordinárias, superiores às dos outros setores da economia. Este excelente desempenho da agricultura nacional ocorreu sem que existisse um aparato de políticas públicas para fomentá-lo. Desta forma, o desempenho da agricultura favoreceu a atuação de grupos de pressão sobre o marco regulatório dos agrotóxicos, no qual segmentos do setor agrícola e entidades representativas de empresas produtoras de agrotóxicos têm procurado reduzir as exigências para o registro de novos produtos, sob a alegação de que isto reduziria os preços dos agrotóxicos ao produtor rural, melhorando a competitividade da agricultura nacional, e ainda promoveria a redução do grau de concentração do mercado brasileiro de... Tipo: Conference Paper or Presentation Palavras-chave: Agrotóxicos; Organização Industrial; Nexo econômico-jurídico; Agricultura; Pesticides; Industrial Organization; Economic-legal nexus; Agriculture; Agribusiness; Crop Production/Industries. Ano: 2008 URL: http://purl.umn.edu/109607 A EXPANSÃO DA CANA-DE-AÇÚCAR E O IMPACTO SOBRE A ARRECADAÇÃO FISCAL DOS MUNICÍPIOS PAULISTAS AgEcon Palomino, Josiane Mayara Gil; Toneto Junior, Rudinei; Campos, Celso Vilela Chaves; Stocco, Leandro. Observa-se no período recente um forte crescimento da produção de etanol e açúcar, fato que vem se refletindo no uso crescente da terra pela cana-de-açúcar. Este processo vem ocorrendo com maior intensidade no estado de São Paulo, fazendo com que vários municípios se tornem cada vez mais dependentes dessa cultura. Com base nisso, a questão que se coloca é como os municípios podem se beneficiar dessa expansão, sendo necessária, então, a análise de pontos como o impacto na arrecadação fiscal, objetivo deste trabalho. Para tanto, foram estimados vários modelos em painel de efeitos fixos, corrigidos para heteroscedasticidade e autocorrelação, que tem como variáveis dependentes a arrecadação per capita do ISSQN, ICMS, IPVA e IPTU. Os dados, extraídos da... Tipo: Conference Paper or Presentation Palavras-chave: Setor sucroalcooleiro. Arrecadação fiscal. Cana-de-açúcar. Dados em painel. Sugarcane sector. Fiscal collection. Sugarcane. Panel data.; Crop Production/Industries; Resource /Energy Economics and Policy. Ano: 2008 URL: http://purl.umn.edu/108069 A farm level assessment of a novel drought tolerant forage:Tedera (Bituminaria bituminosa C.H.Stirt var. albomarginata). AgEcon Finlayson, John D.; Real, Daniel; Nordblom, Thomas L.; Revell, Clinton; Ewing, Michael A.; Kingwell, Ross S.. Tedera (Bituminaria bituminosa C.H.Stirt var. albomarginata) is a drought tolerant perennial legume originating in the Canary Islands. This study evaluates the potential role and value of tedera in dryland mixed crop and sheep production systems in southern Australia. Regional variants of the bio-economic model MIDAS are used to assess tedera in farming systems at two locations. The analysis considers the quantity and quality of feed produced by tedera, the ability of other forages to complement or substitute for tedera and its impact on meat versus wool-producing sheep flocks. The results indicate that tedera offers the potential to increase farm profits by up to 26% and be grown on ~28% of a low rainfall mixed enterprise farm. On a high rainfall mixed... Tipo: Presentation Palavras-chave: Tedera; Drought tolerant; Forage; Legume; Mediterranean-type climate; Autumn feed gap; Bio-economic modelling; Whole farm modelling; Technology evaluation; MIDAS; Model of dryland agricultural system.; Crop Production/Industries. Ano: 2012 URL: http://purl.umn.edu/124297 A Farm-level Approach to the Methyl Bromide Phase-out: Identifying Alternatives and Maximizing Net Worth Using Stochastic Dominance and Optimization Procedures. AgEcon Byrd, Mark M.; Escalante, Cesar L.; Wetzstein, Michael E.; Fonsah, Esendugue Greg. Alternative fumigant and herbicide systems for Georgia's pepper farms are analyzed relative to soon-to-be phased-out methyl bromide system. Stochastic dominance analyses identify two alternatives exceeding MeBr's yield and financial efficiency. A programming model using simulation-optimization techniques provides important implications on the pepper farms' economic viability under these alternative systems. Tipo: Conference Paper or Presentation Palavras-chave: Crop Production/Industries. Ano: 2006 URL: http://purl.umn.edu/35265 A fenntarthatóság mérése az erdőgazdaságban AgEcon Somogyi, Zoltan. A fenntarthatóság mérése, de definiálása is nehézkes a jövőre vonatkozó feltételezések bizonytalansága miatt. Korlátozott következtetések vonhatók le pl. a „kereslet és kínálat” összehasonlításának elvén alapuló, egyre közismertebb ökológiai lábnyomból, vagy más, a fenntarthatóság bizonyos aspektusait részletesebben jellemző indikátorok tényleges értékeinek és az előre elvárt értékek összevetéséből. Ilyen, fejlődő, korlátozott lehetőségeket nyújtó indikátorrendszer jött létre az erdőgazdálkodásban. A rendszer használatát nagymértékben korlátozza, hogy megalapozatlan az, hogy hány, illetve mennyire specifikus vagy mennyire aggregált indikátorokat alkalmaznak, és hogy az indikátorok mért értékeit hogyan értelmezik. Emiatt az indikátorértékek értelmezésében... Tipo: Journal Article Palavras-chave: Fenntartható fejlődés; Erdőgazdálkodás; Fenntarthatósági indikátor; Bioindikátor; Sustainable development; Forest management; Sustainability indicator; Bioindicator; Crop Production/Industries; Environmental Economics and Policy. Ano: 2009 URL: http://purl.umn.edu/92482 A Flexible Parametric Family for the Modeling and Simulation of Yield Distributions AgEcon Ramirez, Octavio A.; McDonald, Tanya U.; Carpio, Carlos E.. The distributions currently used to model and simulate crop yields are unable to accommodate a substantial subset of the theoretically feasible mean-variance-skewness-kurtosis (MVSK) hyperspace. Because these first four central moments are key determinants of shape, the available distributions might not be capable of adequately modeling all yield distributions that could be encountered in practice. This study introduces a system of distributions that can span the entire MVSK space and assesses its potential to serve as a more comprehensive parametric crop yield model, improving the breadth of distributional choices available to researchers and the likelihood of formulating proper parametric models. Tipo: Journal Article Palavras-chave: Risk analysis; Parametric methods; Yield distributions; Yield modeling and simulation; Yield nonnormality; Agribusiness; Agricultural Finance; Crop Production/Industries; Land Economics/Use; Production Economics; Productivity Analysis; Research Methods/ Statistical Methods; C15; C16; C46; C63. Ano: 2010 URL: http://purl.umn.edu/90675 A framework for efficient wastewater treatment and recycling systems AgEcon Mekala, Gayathri Devi; Davidson, Brian; Samad, Madar; Boland, Anne-Maree. Use of un-treated/partially treated wastewater for irrigation in the dry countries of Asia and Africa and recycling of treated wastewater in the water scarce developed countries has become a common practice due to various reasons. While the lack of wastewater treatment to appropriate levels before use is a major problem in developing countries, the high cost of wastewater recycling is the major problem in developed countries. The current paper is part of a doctoral research and presents the conceptual framework for the research and the methodology that can be used to tackle the problems associated with wastewater recycling. Tipo: Working or Discussion Paper Palavras-chave: Water reuse; Wastewater; Recycling; Pricing; Water allocation; Cost benefit analysis; Wastewater irrigation; Developing countries; Developed countries; Case studies; India; Australia; Hyderabad; Melbourne; Agribusiness; Agricultural Finance; Crop Production/Industries; Demand and Price Analysis; Farm Management; Production Economics. Ano: 2008 URL: http://purl.umn.edu/46387 A FRUTICULTURA IRRIGADA EM ÁREAS DE ASSENTAMENTO NO MUNICÍPIO DE BARAÚNA – RN: ANÁLISE DO PROCESSO DE PRODUÇÃO E COMERCIALIZAÇÃO AgEcon Maia, Ana Cristina Nogueira; Costa, Genivalda Cordeiro Da. A fruticultura irrigada foi introduzida no Rio Grande do Norte, no final dos anos 70, pela empresa Maisa Agroindustrial S/A – MAISA, através do cultivo de melão. A partir da década de 80 outras empresas, como por exemplo, a FRUNORTE passaram a produzir melão e outras frutas na região. Porém, a partir de meados da década de 90, o melão passou a ser produzido também por médios e pequenos produtores da região, inclusive por produtores de áreas de assentamentos de Reforma Agrária, os quais se tornaram fornecedores do produto para a agroindústria – que se encarregava da venda do melão junto aos mercados externo e interno (COSTA, 2002). Este estudo teve como objetivo geral: analisar o processo de produção e comercialização da fruticultura irrigada desenvolvida... Tipo: Conference Paper or Presentation Palavras-chave: Produção; Comercialização; Fruticultura irrigada; Production; Trade; Irrigated fruit; Crop Production/Industries. Ano: 2008 URL: http://purl.umn.edu/113197 A Fully Calibrated Generalized CES Programming Model of Agricultural Supply AgEcon Merel, Pierre R.; Simon, Leo K.; Yi, Fujin. The use of prior information on supply elasticities to calibrate programming models of agricultural supply has been advocated repeatedly in the recent literature (Heckelei and Britz 2005). Yet, Mérel and Bucaram (2009) have shown that the dual goal of calibrating such models to a reference allocation while replicating an exogenous set of supply elasticities is not always feasible. This article lays out the methodological foundation to exactly calibrate programming models of agricultural supply using generalized CES production functions. We formally derive the necessary and sufficient conditions under which such models can be calibrated to replicate the reference allocation while displaying crop-specific supply responses that are consistent with prior... Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Generalized CES; Supply elasticities; Crop Production/Industries; Production Economics. Ano: 2010 URL: http://purl.umn.edu/60906 A FŐBB SZÁNTÓFÖLDI NÖVÉNYEK TERMELÉSE ÉS AZ ÁLLATÁLLOMÁNY ALAKULÁSÁNAK KILÁTÁSAI AgEcon Hegedus-Baranyai, Nora. A mindenkori gazdaságpolitikának nagy szüksége van a mezőgazdasági folyamatok összetevőinek megismerésére, a hatások-ellenhatások múltbeli feltérképezésére ahhoz, hogy a jövő agrárstratégiáját már ezek figyelembevételével alakítsa ki. A vizsgálatok a múltbeli tendencia folytatásaként a búza, a kukorica vetésterületének csökkenését, illetve a napraforgó növekedését vetítik előre. A termésmennyiségek prognózisa azt mutatta, hogy a búza, a kukorica és a napraforgó esetében emelkedés várható, amit a hosszú távú ciklusok jövőben várható konjunktúrája még jobban fel fog erősíteni. Az állatállomány trendjének öt éves előrejelzése alapján kirajzolódott az a korántsem pozitív kép, hogy ha a múltbeli tendenciák tovább folytatódnak a sertés- és a... Tipo: Journal Article Palavras-chave: Állatállomány; Szántóföldi növénytermelés; Hosszú távú trend; Jövőprognózis; Ciklus; Livestock; Production of arable land plants; Long-term trend; Future prognosis; Cycle; Agribusiness; Crop Production/Industries; Farm Management; Livestock Production/Industries. Ano: 2007 URL: http://purl.umn.edu/57685 A GABONAPIACI KERESLET SZEREPLŐINEK ÁTALAKULÁSA AgEcon Kemenyne Horvath, Zsuzsanna. A tanulmány bemutatja a hazai gabona keresletében bekövetkezett vertikális és horizontális átrendeződést és annak hatásait. A kérdőíves megkeresés és a mélyinterjúkból született válaszokat felhasználva, klaszteranalízis segítségével lehetővé vált a felvásárlói oldalon álló szereplők tipizálása, továbbá az áralku döntéseik modellezése. Megállapítható, hogy a gabonapiacon elsősorban a nagy kereskedelmi cégek és holdingok az árvezetők, ami méretükkel, tároló kapacitá-saikkal, logisztikai adottságaikkal és stratégiájukkal magyarázható. A feldolgo-zók (malom, takarmánykeverő, vetőmagos cégek), az integrátorok, kiskereskedők és egyéb cégek árelfogadók a gabonapiacon. Az intervenciós árszint a keresleti oldalon álló szereplők áralkuit, gabonapiaci stratégiáját... Tipo: Journal Article Palavras-chave: Gabonapiac; Intervenció; Klaszteranalízis; Keresleti oldal; Áralku; Grain market; Intervention; Cluster analysis; Demand side; Price deal; Agribusiness; Crop Production/Industries; International Relations/Trade; Production Economics. Ano: 2007 URL: http://purl.umn.edu/57664 A gap analysis of confined field trial application forms for genetically modified crops in East Africa: evaluating the potential for harmonization AgEcon Linacre, Nicholas A.; Cohen, Joel I.. The regulatory approval of genetically modified crops in the field initially requires small, restricted experimental trials known as confined field trials. These small scale experiments provide researchers with important information on environmental interactions and agronomic performance of the crop in a safe and contained manner. To authorize confined field trials regulatory review is required, with formats for obtaining relevant information differing from country to country. In this paper, a Gap Analysis is used to identify informational gaps and potential for harmonization of confined field trial application processes in three East African countries - Tanzania, Kenya, and Uganda. The basic principle behind gap analysis is a comparison of the status quo... Tipo: Report Palavras-chave: Genetically modified crops; Gap analysis; Confined field trials; Biotechnology; Biosafety; Crop Production/Industries. Ano: 2006 URL: http://purl.umn.edu/55421 Registros recuperados: 4.955 Primeira ... 3 4 5 6 7 8 9 10 11 ... Última

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