Academic literature on the topic 'Land Equivalent Ratio'
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Journal articles on the topic "Land Equivalent Ratio"
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Ekaka-A, E. N., N. E. S. Lale, and C. C. Wokocha. "The Land Equivalent Ratio and Its Mutualistic Implications: Computational Approach." IOSR Journal of Mathematics 10, no. 4 (2014): 82–85. http://dx.doi.org/10.9790/5728-10448285.
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Riley, Janet. "Examination of the Staple and Effective Land Equivalent Ratios." Experimental Agriculture 21, no. 4 (October 1985): 369–76. http://dx.doi.org/10.1017/s0014479700013193.
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SUMMARYTwo extensions to the Land Equivalent Ratio (LER) concept, the Effective LER and the Staple LER, are evaluated for an intercrop of two species. The use of different standardizing sole-crop yields in the Effective LER equation is emphasized for the formation of different comparisons between intercrop and sole-crop yields. The Staple LER for different standardizing sole-crop yields is introduced. The equivalence of the Staple and Effective LERs under certain conditions is shown and illustrated.
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Hussain, Iqtidar, Shakeel Ahmad Jatoi ., Obaidullah Sayal ., and Muhammad Safdar Balo . "Green Fodder Yield and Land Equivalent Ratio of Sorghum-Legume Association." Pakistan Journal of Biological Sciences 3, no. 1 (December 15, 1999): 175–76. http://dx.doi.org/10.3923/pjbs.2000.175.176.
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Tawfiq, Sherwan Ismael, and Kazhala Rashed Ahmad. "The Role of Intercropping Wheat with Legumes (Chickpea or Pea) in Improving the yield and Land Equivalent Ratio in Rain fed Regions." Journal of Zankoy Sulaimani - Part A 16, special (October 10, 2013): 33–45. http://dx.doi.org/10.17656/jzs.10308.
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Ceunfin, Syprianus, Djoko Prajitno, Priyono Suryanto, and Eka Tarwaca Susila Putra. "Penilaian Kompetisi dan Keuntungan Hasil Tumpangsari Jagung Kedelai di Bawah Tegakan Kayu Putih." Savana Cendana 2, no. 01 (January 27, 2017): 1–3. http://dx.doi.org/10.32938/sc.v2i01.76.
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Penelitian ini bertujuan untuk mengetahui nilai kompetisi dan keuntungan hasil dalam tumpangsari jagung varietas pioner 21 dan kedelai varietas grobogan dibawah tegakan hutan kayu putih. Penelitian ini menggunakan metode percobaan lapangan yang terdiri atas dua faktor dan dirancang dengan menggunakan Rancangan Petak ber-alur. Faktor pertama sebagai petak utama berupa Posisi bidang olah dari kedudukan tegakan kayu putih (Zona) dan faktor kedua sebagai anak petak adalah jarak tanam jagung. Petak utama berupa zona bidang olah terdiri dari 2 aras yaitu zona 1 terletak pada posisi bidang olah yang berjarak 0-1 m dari kedudukan tegakan (Z1); zona 2 terletak pada posisi bidang olah yang berjarak 1-2 m dari kedudukan tegakan (Z2), Anak petak adalah jarak tanam jagung yang terdiri atas 3 aras yaitu: 50 cm x 20 cm (J1), 70 cm x 20 cm (J2) dan 90 cm x 20 cm (J3). Hasil penelitian menunjukkan bahwa Tumpangsari tanaman jagung dan kedelai dibawah tegakan kayu putih sangat menguntungkan.Tanaman jagung lebih agresif dan competitif daripada tanaman kedelai sehingga menyumbangkan keuntungan pada land equivalent ratio total dan area time equivalent ratio dan Actual Yeild loss total pada perlakuan zona pengolahan lahan maupun jarak tanaman. Zona pengolahan lahan 0-1 m dari kedudukan pohon kayu putih memberikan hasil land equivalent ratio total, area time equivalent ratio, dan actual yield loss total paling tinggi yaitu sebesar 1,71, 1,66 dan 0,82 sedangkan Jarak tanam 50 cm x 20 cm memberikan hasil land equivalent ratio total, area time equivalent ratio, dan actual yield loss total paling tinggi yaitu sebesar 2,27, 2,25 dan 1,58. ©2017 dipublikasikan oleh Savana Cendana.
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Runkulatile, Herry, Koki Horama, Takeshi Horie, Takashi Kurusu, and Tatsuya Inamura. "Land Equivalent Ratio of Groundnut-Fingermillet Intercrops as Affected by Plant Combination Ratio, and Nitrogen and Water Availability." Plant Production Science 1, no. 1 (January 1998): 39–46. http://dx.doi.org/10.1626/pps.1.39.
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Salehi, Aliyeh, Sina Fallah, Reinhard W. Neugschwandtner, Bano Mehdi, and Hans-Peter Kaul. "Growth analysis and land equivalent ratio of fenugreek-buckwheat intercrops at different fertilizer types." Die Bodenkultur: Journal of Land Management, Food and Environment 69, no. 2 (October 5, 2018): 105–19. http://dx.doi.org/10.2478/boku-2018-0010.
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Summary Intercropping can increase crop growth and yield due to improved resource use efficiency. A two-year field experiment was performed in Shahrekord (Iran) to determine the effect of crop stand composition and fertilizer type on the productions of aboveground dry matter and growth parameters of fenugreek-buckwheat intercrops. Sole crops of fenugreek (F) and buckwheat (B) were compared to the three substitutive intercropping ratios (F:B = 2:1, 1:1 and 1:2). Crop stands were fertilized with chemical fertilizer or broiler litter. Fenugreek could produce in intercrops a similar amount of above-ground dry matter compared to its corresponding share on the sowing ratio. Contrary to that, buckwheat could produce in intercrops more above-ground dry matter than its share on the sowing ratio, especially with a low to medium share of buckwheat. Consequently, the intercrops with F:B (2:1) and F:B (1:1) had an above-ground dry matter yield advantage compared to the pure crop stands of both crops. Broiler litter was more effective in increasing the growth rates and thus the above-ground dry matter production compared to the chemical fertilizer. Thus, growing fenugreek and buckwheat in intercrops fertilized with broiler litter can be beneficial for increasing the biomass production in semiarid environments.
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Yu, Yang, David Makowski, Tjeerd-Jan Stomph, and Wopke van der Werf. "Robust Increases of Land Equivalent Ratio with Temporal Niche Differentiation: A Meta-Quantile Regression." Agronomy Journal 108, no. 6 (November 2016): 2269–79. http://dx.doi.org/10.2134/agronj2016.03.0170.
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Newman, S. M. "A Pear and Vegetable Interculture System: Land Equivalent Ratio, Light Use Efficiency and Productivity." Experimental Agriculture 22, no. 4 (October 1986): 383–92. http://dx.doi.org/10.1017/s0014479700014630.
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SUMMARYThe productivity, land equivalent ratios (LERs) and light use efficiency of a pear and radish interculture system were assessed. Pear yield was unaffected by intercropping. Relative yields for the radish component varied between 0.5–1.01 depending upon the yield index and spatial arrangement employed. This gave LER values for the system of 1.5–2.01. The overall trans-missivity of the pear canopy was 73%. A 47% reduction in photosynthetically active radiation (PAR) gave a yield reduction of 65% in terms of number of saleable radish, but did not affect total dry matter productivity. Reductions in radish yield directly beneath pear trees was thought to be due to other factors besides PAR. The total dry matter productivity of a system containing five successive radish crops was estimated at 26.25 tonnes ha−1 yr−1.
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Metwally, A., A. Abuldahab, M. Shereif, and M. Awad. "Productivity and Land Equivalent Ratio of Intercropping Cotton with Some Winter Crops in Egypt." American Journal of Experimental Agriculture 14, no. 1 (January 10, 2016): 1–15. http://dx.doi.org/10.9734/ajea/2016/27523.
Full textDissertations / Theses on the topic "Land Equivalent Ratio"
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Bedoussac, Laurent. "Analyse du fonctionnement des performances des associations blé dur-pois d'hiver et blé dur-féverole d'hiver pour la conception d'itinéraires techniques adaptés à différents objectifs de production en systèmes bas-intrants." Phd thesis, Toulouse, INPT, 2009. http://oatao.univ-toulouse.fr/7855/1/bedoussac.pdf.
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Les associations d'espèces sont définies comme la culture simultanée d'au moins deux espèces sur la même parcelle pendant une période significative de leur croissance. Ce système permettrait d'améliorer l'utilisation des ressources du milieu (eau, azote, lumière…) et ainsi d'augmenter le rendement et la qualité des grains par rapport aux cultures monospécifiques. L'objectif de notre travail était d'analyser le fonctionnement et d'évaluer la performance des associations blé dur - pois d'hiver et blé dur - féverole d'hiver pour aider à la conception d'itinéraires techniques adaptés à différents objectifs de production. Pour cela nous avons testé, au cours de trois années d'expérimentations, différentes combinaisons de variétés de blé dur, disponibilités en azote, structures de couverts et densités de plantes. Nos résultats ont confirmé l'intérêt de ces systèmes pour améliorer le rendement et la teneur en protéines du blé dur comparativement aux cultures monospécifiques mais également pour la réduction des ravageurs, maladies et de l'enherbement dans certaines conditions. Ces systèmes sont ainsi particulièrement bien adaptés aux situations à faible disponibilité en azote en raison de la complémentarité entre céréale et légumineuse pour l'utilisation de l'azote (minéral du sol et fixation symbiotique) mais aussi pour la captation de l'énergie lumineuse. In fine, ce travail a permis de proposer des prototypes d'itinéraires techniques d'associations adaptés à différents objectifs de production, grâce notamment à l'analyse dynamique des compétitions et complémentarités entre espèces au sein du couvert et en particulier de l'élaboration du rendement du blé dur en association.
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Barros, Júnior Aurélio Paes [UNESP]. "Adubação nitrogenada no consórcio alface e rúcula." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/105218.
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barrosjunior_ap_dr_jabo.pdf: 517386 bytes, checksum: 645a826a9d61527bb271720029dfffe4 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Com o objetivo avaliar a influência de doses de nitrogênio realizadas para a alface e/ou para a rúcula, em consórcio, sobre as plantas (estado nutricional e crescimento) e sobre o consórcio (produtividade, classificação e qualidade, uso eficiente da área e rentabilidade), foi realizado um experimento no período de setembro à dezembro de 2006, na Unesp, Campus de Jaboticabal-SP. O delineamento experimental foi o de blocos casualizados completos, com quatro repetições, sendo os tratamentos arranjados em esquema fatorial 4 x 4 + 2. Os tratamentos resultaram da combinação de quatro doses de N para a alface (0, 65, 130 e 195 kg/ha de N) e quatro doses de N para a rúcula (0, 65, 130 e 195 kg/ha de N), mais dois tratamentos adicionais, correspondentes às monoculturas de alface e rúcula. As cultivares utilizadas foram Verônica (alface) e Folha Larga (rúcula). Para todas as características avaliadas de plantas de alface a monocultura (testemunha) tiveram melhor desempenho que em consórcios, não ocorrendo diferenças para as características de rúcula. O aumento da dose de N para ambas as culturas, em consórcio, proporcionou incrementos nas características de plantas de alface e rúcula. A máxima produtividade de alface, 23.744,48 kg/ha, foi obtida com 100 kg/ha de N para alface e 195 kg/ha de N para rúcula. A máxima produtividade de rúcula, 14.435,78 kg/ha, foi obtida com a adubação de 195 kg/ha de alface e 180 kg/ha de N para rúcula. A maximização do índice de eficiência de uso da área (1,86) foi obtido na dose 127 kg/ha N para a alface e 195 xv kg/ha N para rúcula. O maior lucro operacional, R$ 29.026,11/ha, foi obtido na combinação de doses de 122 kg/ha N para alface e 195 kg/ha N para rúcula.
In order to evaluate the influence how nitrogen rates used for lettuce and/or rocket, under intercropping, affect the plants (nutrition and growth conditions), and the intercropping (yielding, grading, land equivalent ratio and profitability), an experiment was carried out at the campus of Unesp in Jaboticabal-SP, from September to December 2006. The experiment was conducted in a randomized complete block design, with four replications, treatments being arranged in a 4 x 4 + 2 factorial design. The treatments were the result of a combination of four N rates for lettuce (0, 65, 130 and 195 kg/ha of N), and four N rates for rocket (0, 65, 130 and 195 kg/ha of N), plus two additional treatments, which corresponded to lettuce and rocket under single cropping. Veronica (lettuce) and Folha Larga (rocket) were the cultivars used. For all the plant characteristics of lettuce that were studied, the single cropping (witness) had better performance than in intercropping, whereas no differences were observed for the rocket characteristics. An increase in the N rate for both cultures under intercropping showed gains in the plant characteristics of lettuce and rocket. Maximum lettuce yield, 23,744.48 kg/ha, was achieved with the application of 100 kg N ha for lettuce, and 195 kg N ha for rocket. Maximum rocket yield, 14,435.78 kg/ha, was achieved with the application of 195 kg N ha for lettuce, and 180 kg N ha for rocket. The land equivalent ratio was maximized (1.86) by using 127 kg N ha for lettuce and 195 kg N ha for rocket. The highest xvii operating profit, R$ 29,026.11/ha, resulted from the combination of 122 kg N ha for lettuce and 195 kg N ha for rocket.
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Barros, Júnior Aurélio Paes. "Adubação nitrogenada no consórcio alface e rúcula /." Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/105218.
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Resumo: Com o objetivo avaliar a influência de doses de nitrogênio realizadas para a alface e/ou para a rúcula, em consórcio, sobre as plantas (estado nutricional e crescimento) e sobre o consórcio (produtividade, classificação e qualidade, uso eficiente da área e rentabilidade), foi realizado um experimento no período de setembro à dezembro de 2006, na Unesp, Campus de Jaboticabal-SP. O delineamento experimental foi o de blocos casualizados completos, com quatro repetições, sendo os tratamentos arranjados em esquema fatorial 4 x 4 + 2. Os tratamentos resultaram da combinação de quatro doses de N para a alface (0, 65, 130 e 195 kg/ha de N) e quatro doses de N para a rúcula (0, 65, 130 e 195 kg/ha de N), mais dois tratamentos adicionais, correspondentes às monoculturas de alface e rúcula. As cultivares utilizadas foram Verônica (alface) e Folha Larga (rúcula). Para todas as características avaliadas de plantas de alface a monocultura (testemunha) tiveram melhor desempenho que em consórcios, não ocorrendo diferenças para as características de rúcula. O aumento da dose de N para ambas as culturas, em consórcio, proporcionou incrementos nas características de plantas de alface e rúcula. A máxima produtividade de alface, 23.744,48 kg/ha, foi obtida com 100 kg/ha de N para alface e 195 kg/ha de N para rúcula. A máxima produtividade de rúcula, 14.435,78 kg/ha, foi obtida com a adubação de 195 kg/ha de alface e 180 kg/ha de N para rúcula. A maximização do índice de eficiência de uso da área (1,86) foi obtido na dose 127 kg/ha N para a alface e 195 xv kg/ha N para rúcula. O maior lucro operacional, R$ 29.026,11/ha, foi obtido na combinação de doses de 122 kg/ha N para alface e 195 kg/ha N para rúcula.Abstract: In order to evaluate the influence how nitrogen rates used for lettuce and/or rocket, under intercropping, affect the plants (nutrition and growth conditions), and the intercropping (yielding, grading, land equivalent ratio and profitability), an experiment was carried out at the campus of Unesp in Jaboticabal-SP, from September to December 2006. The experiment was conducted in a randomized complete block design, with four replications, treatments being arranged in a 4 x 4 + 2 factorial design. The treatments were the result of a combination of four N rates for lettuce (0, 65, 130 and 195 kg/ha of N), and four N rates for rocket (0, 65, 130 and 195 kg/ha of N), plus two additional treatments, which corresponded to lettuce and rocket under single cropping. Veronica (lettuce) and Folha Larga (rocket) were the cultivars used. For all the plant characteristics of lettuce that were studied, the single cropping (witness) had better performance than in intercropping, whereas no differences were observed for the rocket characteristics. An increase in the N rate for both cultures under intercropping showed gains in the plant characteristics of lettuce and rocket. Maximum lettuce yield, 23,744.48 kg/ha, was achieved with the application of 100 kg N ha for lettuce, and 195 kg N ha for rocket. Maximum rocket yield, 14,435.78 kg/ha, was achieved with the application of 195 kg N ha for lettuce, and 180 kg N ha for rocket. The land equivalent ratio was maximized (1.86) by using 127 kg N ha for lettuce and 195 kg N ha for rocket. The highest xvii operating profit, R$ 29,026.11/ha, resulted from the combination of 122 kg N ha for lettuce and 195 kg N ha for rocket.
Orientador: Arthur Bernardes Cecílio Filho
Coorientador: Renato de Mello Prado
Coorientador: José Carlos Barbosa
Banca: Francisco Bezerra Neto
Banca: Leilson Costa Grangeiro
Banca: Domingos Fornasieri Filho
Banca: José Ricardo Mantovani
Doutor
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Paut, Raphael. "Analyse des compromis entre diversité cultivée et complexité de gestion à travers le cas d’étude du Verger-Maraîcher : Une approche combinant modélisation et méthodes qualitatives Reducing risk through crop diversification: an application of portfolio theory to diversified horticultural systems Modelling crop diversification and association effects in agricultural systems." Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0724.
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Les vergers-maraichers sont des systèmes mixtes agroforestiers qui visent à optimiser l'utilisation des ressources spatiales et temporelles en produisant des fruits et des légumes sur la même parcelle. De ce point de vue, ces systèmes semblent en mesure de répondre au double enjeu productif et environnemental auquel l’agriculture est confrontée aujourd’hui. Néanmoins, les vergers-maraichers sont caractérisés par une grande complexité structurale et organisationnelle, car ils combinent deux ateliers très exigeants possédant des dynamiques contrastées. Dans cette optique, les conditions permettant d’obtenir un compromis entre résilience des performances et complexification de la gestion du système nécessitent d’être identifiées.L’objectif de ma thèse est donc de caractériser les compromis entre les bénéfices attendus de ces systèmes et les difficultés engendrées par leur complexité structurelle et organisationnelle. La démarche de recherche s’appuie sur le développement de plusieurs modèles qui mobilisent alternativement (i) la théorie du portefeuille ; (ii) le concept de Surface Equivalente Assolée ; (iii) la modélisation dynamique de type états-contrôles.Ces outils de modélisation sont complétés par une approche compréhensive au travers d’entretiens semi-directifs réalisés auprès de 15 agriculteurs du sud-est de la France. La combinaison de ces différentes approches met en évidence quatre résultats principaux. (i) Les effets de la diversification dans un contexte horticole peuvent permettre de réduire la variabilité de la production globale jusqu’à 77% ; (ii) l’association de cultures, en plus d’augmenter le rendement global, réduit davantage le risque ; (iii) la part relative de l’arboriculture et du maraichage dans l’assolement, couplée à l’allocation du temps de travail entre ces deux ateliers sont des éléments déterminants dans la gestion à long terme de la dynamique du système ; (iv) enfin, gérer la complexité liée à la diversité des cultures et à leur agencement agroforestier implique une reconfiguration des pratiques de gestion.L’ensemble de ces résultats met en évidence que la conduite de ces systèmes permet d’arbitrer entre les différentes dimensions étudiées : réduction des risques, synergies entre cultures, différences de dynamiques entre arboriculture et maraichage, mais également, impact de la configuration agroforestière sur les pratiques agricoles. Ces travaux de thèse permettent ainsi de mieux caractériser les compromis entre les bénéfices attendus des vergers-maraichers et la complexité de leur mise en oeuvreThe need to redesign more sustainable agricultural systems able of producing more, especially through intercropping or agroforestry, cannot be achieved without taking into account the essential aspect of production variability. Yet, although many studies have focused on the effect of intercropping on overall production, the particular issue of production variability in such systems remains relatively unstudied. The approach we propose, for a shift towards a sustainable intensification of agricultural systems, considers the dual dimensions of yield and risk in a combined framework for the assessment and the comparison of two diversification strategies: (i) a simple diversification strategy (SDS) considered as an increasing number of crops grown on separate plots within a farm and (ii) an intercropping strategy (IC) considered as a within-plot increased diversity, where more than one species is grown at the same time and place. The two perspectives examined here were Modern Portfolio Theory and Land Equivalent Ratio. The former quantifies the effect of diversification on risk, the latter measures the effect of association on production. This research merges both approaches in a combined framework in order to assess intercropping system performances. By applying our framework to cases selected from the literature, we explored and compared the potential benefits of these two strategies in terms of yield and risk. Results showed that intercropping, in addition to being interesting with regard to yield, can have an additional risk reduction effect compared to a simple diversification strategy. Conversely, some crop mixtures maintained or even increased yield variability. Our work contributes to a better understanding of the possible impacts of diversification strategies on trade-offs between yield and risk, but also underlines the importance of taking yield variability into account in further studies
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Pinto, Ciro de Miranda. "ConfiguraÃÃo e antecipaÃÃo de plantio da mamona em consÃrcio com a cultura do girassol." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6541.
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CoordenaÃÃo de AperfeiÃoamento de NÃvel SuperiorA mamoneira (Ricinus communis) Ã tolerante a seca e cultivada para produÃÃo de Ãleo para uso industrial. Na regiÃo Nordeste os pequenos produtores cultivam a mamona consorciada algodÃo, feijÃo caupi, gergelim, girassol, milho, sorgo ou amendoim. Dois experimentos de campo foram conduzidos nos anos agrÃcolas 2008, 2009 e 2010, na Fazenda Experimental Lavoura Seca, QuixadÃ, CearÃ, com o objetivo de avaliar o comportamento da mamona e girasssol cultivados em dois padrÃes de consorciaÃÃo. No experimento I avaliou-se o consorcio mamona (Ma) x girassol (Gi) com 1Ma:1Gi; 1Ma:2Gi; 1Ma:3Gi; 2Ma:2Gi; 2Ma:3Gi fileiras, acrescidos da mamona e girassol em monocultivo. No experimento II, avaliou-se o consorcio mamona x girassol com antecipaÃÃo do plantio da mamona em 0, 7, 14 ou 21 dias antes do plantio do girassol. Para cada experimento adotou-se o delineamento de blocos ao acaso com 4 repetiÃÃes. Avaliou-se a produtividade de grÃos, seus componentes e o uso eficiente da terra para a mamona e girassol consorciados e em monocultivo. A produtividade da mamona e girassol no monocultivo foi significativamente superior nos dois sistemas de consÃrcio. A antecipaÃÃo do plantio da mamona 14 e 21 dias em comparaÃÃo ao girassol mostraram vantagens em relaÃÃo as demais datas de plantio. No experimentos I e II verificou-se que a mamona foi dominante sobre ao girassol. PrecipitaÃÃes pluviais inferiores a demanda hÃdrica das culturas da mamona e girassol, proporcionaram reduÃÃo no uso eficiente de terra (UET).
Castor bean (Ricinus communis L.) is an oil seed crop drought tolerant with its oil having several uses in industry. In the Northeast of Brazil it is commonly cultivated by small farmers intercropped with cotton, cowpea, sesamum, sunflower, sorghum or peanuts. Two field experiments were carried during 2008, 2009 and 2010, at â Fazenda Experiental Lavoura Secaâ, Quixada, Ceara, with the objective to evaluate the behavior of castor bean and sunflower under two intercropping arrangements. In experiment I, its was evaluated the intercropping castor bean (CB) x sunflower (SF) with 1CB:1SF; 1CB:2SF; 1CB:3SF; 2SB:2SF; 2CB:3SF rows, added of sole crop of castor bean and sunflower. In the experiment II, was evaluated with the early planting of castor bean in 0, 7, 14 or 21 days in relations to sunflower the intercropping systems. In both experiments it was used a randomized complete block design with 4 replications. In this study it was determined the yield, yield components and land equivalent ratio (LER) for castor bean and sunflower grown in intercropping and sole crop. The grain yield of castor bean and sunflower was significantly higher in sole crop than intercropping in both experiments. Between the intercropping systems the highest yields were observed when early planting of castor bean was of 14 or 21 days before sunflower. In experiments I and II, showed that the castor bean was the dominant crop in relation to sunflower. Rainfall lower the water requirements of castor bean and sunflower crops, showed a reduction in LER.
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Talbot, Grégoire. "L'intégration spatiale et temporelle du partage des ressources dans un système agroforestier noyers-céréales : une clef pour en comprendre la productivité ?" Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2011. http://tel.archives-ouvertes.fr/tel-00664530.
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Des mesures sur parcelles agroforestières (mélanges d'arbres et de cultures) expérimentales mettent en évidence des productivités exceptionnelles, avec des gains de plus de 30% par rapport à l'assolement de cultures pures. Nous avons mis au point et utilisé un modèle numérique dynamique en 3-D (Hi-sAFe) pour (1) tester si l'intégration spatio-temporelle du partage des ressources (lumière, eau, azote) entre espèces suffit à expliquer cette productivité et (2) évaluer l'impact de différents choix de conception ou de gestion sur cette productivité, à partir d'une compréhension des processus impliqués. Nous avons développé une méthode originale d'analyse des données simulées pour identifier et hiérarchiser les processus déterminant le rendement. Le modèle a été paramétré et calibré sur un système noyer hybride / blé dur situé sur le domaine de Restinclières (Hérault, France). Après une analyse détaillée du fonctionnement de ce système, nous avons exploré par expérimentation virtuelle sa réponse à des choix de conception : (1) traits phénologiques des espèces associées, et (2) densité et disposition des arbres sur la parcelle. Par la richesse de son comportement, Hi-sAFe permet un regard nouveau sur le fonctionnement des systèmes agroforestiers. Il éclaire la complexité du système réel. Nos résultats permettent de proposer une interprétation déterministe du rendement de chaque espèce et de la productivité totale de l'association (Land Equivalent Ratio). L'analyse des expérimentations virtuelles permet de proposer des pistes concrètes pour l'optimisation des systèmes agroforestiers.
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Wang, Zhaozhi. "Predicting toxic gas concentrations resulting from enclosure fires using the local equivalence ratio concept linked to fire field models." Thesis, University of Greenwich, 2007. http://gala.gre.ac.uk/6338/.
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The central idea behind the newly developed toxicity model is the use of the Local Equivalence Ratio (LER). The species yields as functions of the Global Equivalence Ratio (GER) and temperature are input parameters of this model. Correlations for most building materials are available from small-scale fire experiments. Similar approaches to this method are also developed using the CO/CO2 and H2/H2O mole ratios. The LER methodology is further refined by an approach which divides the computational domain for the calculation of toxic gases into two parts, a control region in which the toxic gases are dependent on the LER and temperature, and a transport region in which the toxic gas concentrations are dependent on the mixing of hot gases with fresh air. The toxicity model is then extended to two-fuel cases. In the two-fuel model, the LER is a function of the two mixture fractions, which are used to represent the mixture of the two different fuels, oxygen and combustion products. This model is useful in simulating residential fires, in which wood lining of sidewalls or ceilings is the second fuel. Finally, the transportation of HCI within fire compartments is considered. A mathematical model is developed to simulate the exchange of HCI between gas boundary and wall surfaces and the reaction of HCI with walls. All the toxicity models developed in this study can be integrated into the practical volumetric heat source approach and the Eddy Break-up (EBU) combustion model typically used in practical engineering analysis.
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Maimela, Katlego Alocia. "Performance of five cowpea (Vigna uguiculata L.) varieties in cowpea/maize strip intercropping in Limpopo." Thesis, 2019. http://hdl.handle.net/10386/2972.
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Thesis (MSc. Agriculture (Agronomy)) -- University of Limpopo, 2019The traditional practice of farmers in Limpopo Province is to mixed and broadcast crops at planting without definite row arrangement. This practice hinders farm input application and results in low crop yields. Strip intercropping, where crops are planted with definite row arrangement, has the advantage of reducing inter-species competition, optimise plant population and increasing crop yield. This study aimed at improving cowpea-maize cropping systems using strip intercropping. The experiment was conducted at University of Limpopo farm and Ga-Thaba village. Five cowpea varieties (Glenda (check)), IT86K-499-35, IT82E-16, IT86D -1010, TVu-13464 and maize (PAN 6479) were evaluated using randomised complete block design with three replications. Data collected were days to flowering, days to maturity, plant height, canopy width, peduncle length, pod length, number of pods/plant, 100 seed weight, grain yield, fodder weight and land equivalent ratio was also determined. Data were analysed using the Statistix 9.0. The results revealed that in both locations TVu 13464 flowered early (50 days) respectively. At University of Limpopo farm TVu 13464, IT82E-16 and IT86D-1010 matured early (89, 88 and 91 days). At University of Limpopo farm, IT82E-16 had high cowpea grain yield (2230 kg/ha) under monocropping and also produced high grain yield of 1373 kg/ha during 2016/17 season. At Ga-Thaba, IT86D-1010 produced high cowpea grain yield of 1085 kg/ha under monocropping and during 2015/16 (660 kg/ha) while IT86K-499-35 also produced high grain yield of 915 kg/ha during 2016/17. The varieties showed yield stability depending on different locations. At University of Limpopo farm, strip intercropping achieved high maize grain yield of 3961 kg/ha during 2016/17. At Ga-Thaba, strip intercropping produced high maize grain yield 747 and 1024 kg/ha during 2015/16 and 2016/17, respectively. Monocropping produced low maize grain yield during 2015/16 with a mean of 425 kg/ha and mixed intercropping had mean of 499 kg/ha during 2016/17. The calculated LER for two crops over two seasons under strip intercropping ranged from 1.25 and 2.14, whereas under mixed intercropping, it ranged between 0.73 and 1.05 over two seasons at University of Limpopo farm. TVu 13464, IT82E-16 and IT86D-1010 are promising varieties for strip intercropping in low rainfall areas because of their early maturity and high grain yield. The calculated LER for two crops over two seasons xx under strip intercropping ranged from 1.62 and 2.98, whereas under mixed intercropping, it ranged between 0.76 and 1.67 in both seasons at Ga-Thaba.
National Research Foundation (NRF) and Water Research Commission (WRC)
Book chapters on the topic "Land Equivalent Ratio"
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Bezgodov, Andrei Viktorovich. "Advantages of Growing Field Peas in Mixed Crops With Rapeseed and Mustard." In Culture. Science. Education: modern trends, 226–34. Publishing house Sreda, 2020. http://dx.doi.org/10.31483/r-74741.
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In field experiences studies on growing field peas in single-component and mixed seeding with spring rape and white mustard were conducted in the Middle Urals. The crop capacity was increased by 10,8% as well as the total yield was increased by 2.3 times up to 2.14 t / ha by the use of spring rape as a supporting and compacting crop in sowng peas with a seeding rate at 0.6 million / ha. It was found out that crop productivity of peas was decreased by 19.4% when the seeding rate was established at 0.4 million / ha, and the crop productivity of spring rape remained at the level of pure sowing – 1.23 t / ha. The total yield, in comparison with the pure sowing of peas, increased by 2.1 times from 0.93 to 1.98 t / ha. Mustard is less suitable as a supporting crop, although it ripes earlier and does not thrive in contrast to spring rape. The total yield and ratio of land equivalents in a mixture with spring rape is higher than with mustard and ranged from 1.66 to 1.98. Peas accounts for the bulk of the total yield (LERab = 0.81...1.48). The coefficients of competitiveness and aggressiveness of the studied crops in mixed sowing indicate the dominant role of field peas in the pea-rape and pea-mustard agrocenoses. The awned and foliose morphotype of field peas when grown in a mixture with mustard showed themselves equally, their competitiveness and aggressiveness coefficients were in a close range – Crab = 2.37...4.57; CAab = 0.72...1.87. The awned morphotype of field peas had the greatest aggressiveness and competitiveness when cultivated in a mixture with spring rape – CRab=6.78...17.80; CAab = 3.35...5.79. The foliose morphotype of field peas occupied an intermediate position and had a good competitive ability with less aggressiveness towards spring rape – Crab = 2.64...2.66; CAab = 2.06...2.13.
Conference papers on the topic "Land Equivalent Ratio"
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Lampert, Dieter, Robert F. Steele, Markus Rosenfelder, and Salvatore DellaVilla. "Equivalent Availability Measurement for Combined-Cycle Power Plants: A New Approach." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0579.
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The Equivalent Availability Factor (EAF) is the most important RAM characteristic in statistics for benchmarks and guarantees for power plants. It represents an energy ratio of the amount available in a period and the theoretical maximum. Representing the impact of scheduled and forced outages of components along with any deratings, a large number of parameters are involved from design, operation to the environment. In 1993, ABB and SPS commenced a cooperation on the fields of data procurement and recording. ABB brought large experience as a power plant supplier, SPS its competence as the leading firm specialized on RAM data service for the power industry worldwide. In May 2000 ALSTOM affiliated the whole power generation division of ABB. ALSTOM and SPS agreed to complete their periodic reports on time based reliability and availability data with EAF data. As the available energy must be calculated from the attributes of its components — in contrast to the effective produced energy that can be measured — the question of accuracy arises. Starting from the definition formula set as standard by ISO 3977/9 (former ANSI/IEEE 762), different methods have been considered to find the most suitable approach. The accuracy of comparisons of plants of different designs and operation modes and the ability to interpret the results is a measure for the suitability of the model chosen. Finally, some recommendations to handle and apply the EAF in the power plant business are given.
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Zhang, Chao. "Low Cycle Fatigue Crack Initiation of Rotating Structures Under Biaxial Stress States." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59249.
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Rotating structures can experience biaxial stress states with a wide range of biaxiality ratios on structure surfaces. Low cycle fatigue (LCF) crack initiation in such conditions demonstrates different fatigue characteristics in terms of crack orientation, fatigue life, etc. The biaxial stress states can be categorized into two types: in-phase and out-of-phase under which fatigue characteristics can be significantly different according to rig test results. This paper presents an investigation of LCF crack initiation under in-phase and out-of-phase biaxial stress states based on rig test results of a nickel alloy. The crack orientations are reviewed and discussed at different stress states. Relations of biaxial LCF life debit factor vs biaxiality ratio are derived (the debit factor is defined as a ratio of the LCF life at a biaxial stress state to the LCF life at corresponding uniaxial stress state which has same cyclic and mean stresses as the primary cyclic and mean stressees of the biaxial stress state). The rig test results showed that the crack orientation is usually normal to the primary stress vector under in-phase biaxial stress states but is inclined to the primary stress vector under out-of-phase stress states. As per the derived biaxial LCF life debit factors, the LCF life was found to be slightly reduced with increasing biaxiality ratios under in-phase biaxial stress states but significantly reduced under out-of-phase biaxial stress states compared with corresponding uniaxial primary stress states. The equivalent cyclic stress fatigue criterion is also employed to theoretically model the biaxial LCF life debit factor under in-phase biaxial stress states. The hydrostatic cyclic stress is included in the equivalent cyclic stress in order to take into account the hydrostatic cyclic pressure effects. The equivalent cyclic stress in the criterion can physically reflect the materials’ ductility reduction under in-phase multiaxial stress states.
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Drennan, Scott A., Chen-Pang Chou, Anthony F. Shelburn, Devin W. Hodgson, Cheng Wang, Chitralkumar V. Naik, Ellen Meeks, and Hasan Karim. "Flow Field Derived Equivalent Reactor Networks for Accurate Chemistry Simulation in Gas Turbine Combustors." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59861.
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A method has been developed in which the flow field predicted by Computational Fluid Dynamics (CFD) is automatically condensed into an Equivalent Reactor Network (ERN), composed of well stirred reactors, allowing rapid and accurate analysis of emissions. This paper presents the effectiveness of utilizing an ERN that is a direct abstraction of the computational flow field for combustion analysis. The CFD results are divided into reactors using various filters on flow-field variables to construct an ERN that represents the 3-D combustor flow field and flame structure. Detailed kinetics can then be used in ERN simulations to analyze effects of fuel composition and operating condition on emissions. The technique is applied to a commercial industrial gas turbine combustor fuel injector and compared against experimental emissions results. Sensitivity of emissions predictions to different parameters in the network extraction is also presented. Parameter variations in fuel flow rate are applied to the ERN to obtain relative impacts of fuel-air ratio on the emissions of NOx without requiring new CFD solutions. This automatic approach has been found to reduce the time required to construct and analyze flow field derived ERNs with detailed chemistry by 90%. A local calculation of Damko¨hler number, important for stability analysis, is also presented. This calculation also uses abstracted information from the CFD flow field and detailed-kinetics simulations for more accurate, cost-effective analysis.
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Yoon, JeongJung, and HeonSeok Lee. "The Study on Development of Low NOx Combustor With Lean Burn Characteristics for 20 kW Class Microturbine." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53200.
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In order to reduce NOx emissions for the 20kW class microturbine under development, the low NOx characteristics were investigated as an application of the lean burn premixed combustion technology. This study was performed under the conditions of high temperature and high pressure. The compressed air of 2.5bar, 3.0bar, and 5.0bar with temperature of 560K was supplied to the combustor through the preheater. The exhaust air was sampled and measured at the immediate exit of the combustor. It is found that NOx increased while CO decreased as increasing inlet air temperature and pressure. NOx decreased, but CO increased as increasing mass flow of inlet air. Equivalent ratio was maintained between 0.10 and 0.16 in the lean region. NOx increased along equivalent ratio, while CO decreased because of the influence of flame temperature. Through numerical approach work with an appropriate combustion model, a complicated swirling flow pattern was predicted, and numerical values of NOx and CO emission were calculated and compared with experiments. As the results of this study, NOx can be reduced up to less than 42ppm at 15% of oxygen when the 20kW class microturbine is operated at design condition.
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Ghenaiet, Adel. "Analyses and Optimization of a Propulsion Cycle for Unmixed High Bypass Turbofan." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50340.
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This paper deals with a parametric study and an optimization for the design variables of a high bypass unmixed turbofan equipping commercial aircrafts. The objective of the first part of this study is to highlight the effects of the principal design parameters (bypass ratio, compression ratios, turbine inlet temperature etc..) on the uninstalled performance, in terms of specific thrust and specific fuel consumption. The second part concerns the optimization, aiming at finding the optimum design parameters concurrently minimizing the specific fuel consumption at cruise, and meeting the thrust requirement at takeoff. The cycle analyzer (on-design and off-design) as coupled to the optimization algorithm MMFD by adopting a random multi-starts search strategy is shown to be stable and converging. The predefined requirements and constraints have dictated utilizing an engine with a high-bypass ratio, high-pressure ratio and a moderate turbine inlet temperature. In general, the obtained results compare fairly well with typical data available for an equivalent ‘reference’ engine. This elaborated methodology is shown to be consistent with the conceptual design requirements and accuracy, because, it does not use components’ characteristics, and operates on simplifying assumptions. This present methodology can be readily adapted for other configurations of aero-engines as well, and easily integrated in a multi-disciplinary design approach.
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Ogata, Takashi, and Takayuki Sakai. "Life Prediction Method of CC and DS Ni Base Superalloys Under High Temperature Biaxial Fatigue Loading." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59069.
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Polycrystalline conventional casting (CC) and directionally solidified (DS) Ni base superalloys are widely used as gas turbine blade materials. It was reported that surface of a gas turbine blade is subjected to biaxial tensile-compressive fatigue loading during start-stop operation based on finite stress analysis results. It is necessary to establish life prediction method of these superalloys under biaxial fatigue loading for reliable operation. In this study, the in-plane biaxial fatigue tests with different phase of x and y directional strain cycles were conducted on both a CC and a DS Ni base superalloys (IN738LC and GTD111DS) at high temperatures. The strain ratio, φ was defined as a ratio between x and y directional strains at 1/4 cycle and was varied from 1 to −1. In φ = 1 and −1, cracks propagated in both x and y directions in the CC supealloy. On the other hand, the main cracks of the DS superalloy propagated only in the x direction indicating failure resistance in the solidified direction is weaker than that in the direction normal to the solidified direction. Although biaxial fatigue life of the CC superalloy was correlated with conventional Mises equivalent strain range, that of DS superalloy was not. New biaxial fatigue life criterion, equivalent normal strain range for the DS superalloy was derived from iso-fatigue life curve on a principal strain plane defined in this study. Fatigue life of the DS superalloy was correlated with the equivalent normal strain range. Fatigue life of the DS superalloy under equi-biaxial fatigue loading was significantly reduced by introducing compressive strain hold dwell. Life prediction under equi-biaxial fatigue loading with the compressive strain hold was successfully made by the nonlinear damage accumulation model indicating that the proposed method can apply to life prediction of gas turbine blades under biaxial fatigue loading.
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Oh, Sang Hyun, Dong Hyun Lee, Kyung Min Kim, Moon Young Kim, and Hyung Hee Cho. "Enhanced Cooling Effectiveness in Full-Coverage Film Cooling System With Impingement Jets." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50784.
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An experimental investigation is conducted on the cooling effectiveness of full-coverage film cooled wall with impingement jets. Film cooling plate is made of stainless steel, thus the adiabatic film cooling effectiveness and the cooling effect of impingement jet underneath the film cooling plate are comprised in the cooling effectiveness. Infra-red camera is used to measure the temperature of film cooled surfaces. Experiments are conducted with different film cooling hole angles, such as 35° and 90°. Diameters of both film cooling holes and impinging jet holes are 5 mm. The jet Reynolds number base on the hole diameter (Red) ranges from 3,000 to 5,000 and equivalent blowing ratios (M) varies from 0.3 to 0.5, respectively. The distance between the injection plate and the film cooling plate is 1, 3 and 5 times of the hole diameter. The streamwise and spanwise hole spacing to the hole diameter ratio (p/d) are 3 for both the film cooling hole plate and the impingement jet hole plate. The 35° angled film cooling hole arrangement shows higher film cooling effectiveness than the 90° film cooling hole arrangement. As the blowing ratio increases, the cooling effectiveness is enhanced for both the 35° almost constant regardless of H/d, while H/d = 1 shows a minimum value for the angled film cooling hole.
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Becker, Julian, and Christoph Hassa. "Liquid Fuel Placement and Mixing of a Generic Aeroengine Premix Module at Different Operating Conditions." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30102.
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Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.
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Ghenaiet, Adel. "Optimization of Turbofan Propulsion Cycle Using a Genetic Algorithm." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22420.
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This paper presents an evolutionary approach as the optimization framework to design for the optimal performance of a high-bypass unmixed turbofan to match with the power requirements of a commercial aircraft. The parametric analysis had the objective to highlight the effects of the principal design parameters on the propulsive performance in terms of specific fuel consumption and specific thrust. The design optimization procedure based on the genetic algorithm PIKAIA coupled to the developed engine performance analyzer (on-design and off-design) aimed at finding the propulsion cycle parameters minimizing the specific fuel consumption, while meeting the required thrusts in cruise and takeoff and the restrictions of temperatures limits, engine size and weight as well as pollutants emissions. This methodology does not use engine components’ maps and operates on simplifying assumptions which are satisfying the conceptual or early design stages. The predefined requirements and design constraints have resulted in an engine with high mass flow rate, bypass ratio and overall pressure ratio and a moderate turbine inlet temperature. In general, the optimized engine is fairly comparable with available engines of equivalent power range.
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Rajoo, Srithar, and R. F. Martinez-Botas. "Lean and Straight Nozzle Vanes in a Variable Geometry Turbine: A Steady and Pulsating Flow Investigation." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50828.
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Variable Geometry Turbines (VGT) are widely used to improve engine-turbocharger matching and currently common in diesel engines. VGT has proven to provide air boost for wide engine speed range as well as reduce turbo-lag. This paper presents the design and experimental evaluation of a variable geometry mixed flow turbocharger turbine. The tests have been carried out with a permanent magnet eddy current dynamometer within a velocity ratio range of 0.47 to 1.09. The peak efficiency of the variable geometry turbine corresponds to vane angle settings between 60° and 65°, for both the lean and straight vanes in the region of 80%. The variable geometry turbine was tested under pulsating flow with straight and lean nozzle vanes for different vane angle settings, 40Hz and 60Hz flow. In general, the range of mass flow parameter is higher in the straight nozzle vanes with an average of 66.4% and 69.7% for 40Hz and 60Hz flow respectively. The straight nozzle vanes also shows increasing pressure ratio range compared to the lean nozzle vanes, which is more apparent in the maximum pressure ratio experienced by the turbine in an unsteady cycle. In overall, the cycle averaged efficiency in the straight vane configuration is marginally higher than the lean vane. Furthermore, the difference to the equivalent quasi-steady is better in the straight vane configuration compared to the lean vane.
Reports on the topic "Land Equivalent Ratio"
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Fernandes, R., M. Maloley, and F. Canisius. Relationship between leaf area index and Landsat Operational Land Imager equivalent reduced simple ratio vegetation index for the Athabasca oil sands region, northern Alberta. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/308333.
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