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Mecanismos elevadores de agua para riegos
1956
Molenaar, A.
Las estrellas microscópicas del agua (Pediastrum) Full text
1946
Margalef, Ramón
4 pages | En el estudio de los organismos más elementales hallamos materia de maravilla e instrucción, pues con frecuencia nos enseñan, en una forma simplificada, esquemática y descarnada, la esencia de fenómenos y procesos que adquieren una extremada complejidad en los seres superiores. De aquí el alto valor educativo de las observaciones microscópicas bien orientadas, que no deberían ser descuidadas en ningún plan de instrucción de nuestra época. [...] P. Boryanum (Turp.), P. simplex var. duodenarium (Bail.) Rabh., P. simplex var. radians Lemm., Arkenasy var. Boryanum (Turp.), P. tetrax [...] | Peer reviewed
Show more [+] Less [-]Uso económico del agua de riego
1944
Powers, W. L. (Wilbur Louis)
Biblioteca electronica de calidad del agua
Facilita el uso de materiales de consulta relacionados con la calidad del agua.
Show more [+] Less [-]Agua para la producción. La experiencia de construcción de tres tipos de obras de captación de agua para su uso en la producción: cosecha de agua, pozos excavados a mano y pilas de captación de agua desde manantiales.
2015
Maradiaga Corea, Marco Antonio | López Fonseca, Ernesto Antonio | Palma Zepeda, Osman | Arévalo Castillo, Alfonso Alejandro
Esta publicación es el resultado de un proceso de sistematización participativo facilitado por el Centro Internacional de Agricultura Tropical (CIAT) para el Programa de Gestión Rural Empresarial, Sanidad y Ambiente (PROGRESA). Este documento tiene como propósito compartir la experiencia de construcción de tres tipos de obras de captación de agua para su uso en la producción: obras para la cosecha de agua (lagunetas y reservorios), pozos excavados a mano y pilas de captación de agua desde manantiales.
Show more [+] Less [-]THE VALUE OF WATER IN THE FERTIRRIGATED MELON PRODUCTION SYSTEM | O VALOR DA ÁGUA NO SISTEMA DE PRODUÇÃO DO MELÃO FERTIRRIGADO Full text
2023
Valnir Júnior, Manoel | Almeida, Aldênia Mendes Mascena de | Nascimento, Valdelânia Ripardo | Brito, Maria Josiely Rodrigues | Carvalho, Clayton Moura de | Sousa, Carlos Henrique Carvalho de
The objective of this work is to evaluate the value of water in the melon production system in different irrigation managements. The experiment was carried out in a plot located in DIBAU, in which all cultural treatments were the same, differing only in terms of water use. The evaluated irrigation managements were two, M1 and M2 controlled by the Ômega system that uses the evaporation of the Class A tank, which adopt kt equal to 1.0 and 0.75, respectively, and M3 by a spreadsheet with an irrigation scheme used by the local producers. The total cost (TC) of production averaged R$ 27,897.41 ha-1, with a variation of R$ 276.06 between managements, although M1 used less than half the water of M3. Fixed costs, with inputs and labor, represent more than 90% of the total cost. The costs involving irrigation (water + energy) represented 1 to 2% of the TC between treatments. It is concluded that the production system requires a considerable investment to cover production costs and that although water is an essential resource for irrigated systems, it has little impact on TC, regardless of the amount of water applied. | O VALOR DA ÁGUA NO SISTEMA DE PRODUÇÃO DO MELÃO FERTIRRIGADO MANOEL VALNIR JÚNIOR1; ALDÊNIA MENDES MASCENA DE ALMEIDA2; VALDELÂNIA RIPARDO NASCIMENTO3; MARIA JOSIELY RODRIGUES BRITO4; CLAYTON MOURA DE CARVALHO5 E CARLOS HENRIQUE CARVALHO DE SOUSA6 1 Doutor, Professor, Instituto Federal de Educação, Ciência e Tecnologia do Ceará – IFCE, Campus Sobral, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: [email protected] 2 Doutora, Pesquisadora Bolsista, Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: [email protected] 3 Discente em Tecnologia de Irrigação e Drenagem, Instituto Federal de Educação, Ciência e Tecnologia do Ceará – IFCE, Campus Sobral, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: [email protected] 4 Mestranda em Engenharia Agrícola, Universidade Federal do Ceará – UFC, Centro de Ciências Agrárias - CCA/UFC, Bloco 804, s/n - Pici, Fortaleza - CE, 60455-760, e-mail: [email protected] 5 Doutor, Pesquisador Bolsista, Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: [email protected] 6 Doutor, Professor, Faculdade Ieducare - FIED, R. Cons. João Lourenço, n 406 - Centro, Tianguá - CE, 62320-000 e-mail: [email protected] 1 RESUMO O trabalho tem por objetivo avaliar o valor da água no sistema de produção do melão em diferentes manejos de irrigação. O experimento foi realizado em um lote localizado no DIBAU, no qual todos os tratos culturais foram iguais diferindo apenas quanto ao uso da água. Os manejos de irrigação avaliados foram dois, M1 e M2 comandados pelo sistema Ômega que utiliza a evaporação do tanque Classe A, que adotam kt igual a 1,0 e 0,75, respectivamente e o M3 por uma planilha com esquema de irrigação usada pelos produtores locais. O custo total (CT) de produção foi em média de R$ 27.897,41 ha-1, com variação de R$ 276,06 entre os manejos, embora o M1 tenha utilizado menos da metade da água do M3. Os custos fixos, com insumos e mão de obra, representam mais de 90% do custo total. Já os custos que envolvem a irrigação (água + energia) representaram de 1 a 2% do CT entre os tratamentos. Conclui-se que o sistema de produção requer um considerável investimento para cobrir os custos de produção e que embora a água seja um recurso essencial aos sistemas irrigados, esta tem pouca expressividade sobre o CT, independente dá quantidade de água aplicada. Palavras-chave: Manejo de irrigação, Cucumis melo L., Custo de produção. VALNIR JÚNIOR, M; ALMEIDA, A. M. M.; NASCIMENTO, V. R.; BRITO, M. J. R.; CARVALHO, C. M.; SOUSA, C. H. C. THE VALUE OF WATER IN THE FERTIRRIGATED MELON PRODUCTION SYSTEM 2 ABSTRACT The aim of this work was to evaluate the value of water in melon production systems under different irrigation management practices. The experiment was carried out on a plot located in DIBAU, in which all the culture treatments were the same and differed only in terms of water use. Two irrigation systems, M1 and M2, controlled by the Omega system, which uses evaporation from the Class A tank and adopts kt values equal to 1.0 and 0.75, respectively, were evaluated, and M3 was controlled by a spreadsheet with an irrigation scheme used by local producers. The total cost (CT) of production averaged R$ 27,897.41 ha -1, with a variation of R$ 276.06 between management practices, although M1 used less than half the water of M3. Fixed costs, with inputs and labor, represent more than 90% of the total cost. The costs of irrigation (water + energy) represented 1 to 2% of the total costs of the CT treatment. It is concluded that the production system requires a considerable investment to cover production costs and that although water is an essential resource for irrigated systems, it has little influence on CT, regardless of the amount of water applied. Keywords: Irrigation management, Cucumis melo L., Production cost.
Show more [+] Less [-]Agua y capacidad de carga económica del turismo en Paracas, Perú | Water and economic carrying capacity of tourism in Paracas, Peru Full text
2022
Pérez-Liu, Rosario | Pérez-Liu, Rosario
The diversification of productive activities reduces the economic vulnerability of a locality; but, at the same time, competition for local resources such as water increases, particularly if it is an arid area. This study analyzes whether the growth of tourism in Paracas, a town located on the desert coast of Peru, can be limited by the scarcity of that resource and if it could interfere with the growth of other local activities. To do this, qualitative and quantitative research techniques and the concept of economic carrying capacity of tourism are used. The study concludes that, in the short term, both tourism and other activities can continue to grow without entering into conflicts. But in the long term problems are likely to arise unless they reduce the excessive pressure they are putting on water consumption. | La diversificación de las actividades productivas reduce la vulnerabilidad económica de una localidad, pero, al mismo tiempo, aumenta la competencia por los recursos locales, como el agua, particularmente si se trata de una zona árida. Este estudio analiza si el crecimiento del turismo en Paracas, ubicada en la desértica costa de Perú, puede verse limitado por la escasez de ese recurso y si podría interferir con el crecimiento de otras actividades locales. Se utilizó el concepto de capacidad de carga económica del turismo y se aplicaron técnicas cuantitativas y cualitativas. El estudio concluye que, a corto plazo, tanto el turismo como las demás actividades pueden continuar creciendo sin entrar en conflictos, pero a largo plazo es probable que surjan problemas a menos que reduzcan la presión excesiva que están ejerciendo sobre el agua.
Show more [+] Less [-]Productividad del agua y rendimiento de maíz bajo diferente disponibilidad de humedad | Water productivity and corn yield under different humidity availability Full text
2021
Alonso-Sánchez, Homero | Tadeo-Robledo, Margarita | Espinosa-Calderón, Alejandro | Zaragoza-Esparza, Job | López-López, Consuelo
Resumen La experimentación con híbridos para condiciones con escasez de agua es fundamental para la seguridad hídrica y alimentaria, integrando el manejo de cultivos con el de los recursos hídricos. El objetivo en este trabajo fue definir la productividad del agua, el rendimiento de grano y el peso hectolítrico en tres ambientes con diferente disponibilidad de humedad: riego y temporal en la FESC-UNAM y riego en Texcoco, Estado de México; utilizando cinco híbridos de maíz de la UNAM y cinco del INIFAP, con dos densidades de siembra. Se estableció el experimento en bloques completos al azar y se registraron variables durante el ciclo y a la cosecha; la productividad total del agua se calculó como el volumen total de agua entre el rendimiento de grano a 14% de humedad. Utilizando SAS se realizó el ANOVA para el análisis de los factores y sus interacciones, se separaron las medias con la prueba de Tukey al 5%. Se encontró efecto de la interacción ambiente x híbrido e híbrido x densidad de siembra en la productividad total del agua. En el rendimiento de grano se encontró efecto de la interacción ambiente x híbrido, ambiente x densidad e híbrido x densidad. Se encontró efecto altamente significativo en el peso hectolítrico del ambiente y del tipo de híbrido. La interacción del híbrido Atziri Puma con los ambientes y con la densidad de siembra mostraron los valores máximos de productividad total del agua y del rendimiento de grano. | Abstract Experimenting with hybrids for conditions with scarce water is essential for water and food security, integrating crop management with that of water resources. The objective of this work was to define water productivity, grain yield, and hectolitre weight in three environments with different humidity availability: irrigation and rainfed in the FESC-UNAM and irrigation in Texcoco, State of Mexico; using five corn hybrids from UNAM and five from INIFAP, with two planting densities. The experiment was established in complete random blocks and variables were registered during the cycle and at harvest; total water productivity was calculated as the total volume of water between grain yield at 14% humidity. Using SAS, ANOVA was performed to analyze the factors and their interactions, the means were separated with the Tukey test at 5%. The effect of the interaction environment x hybrid and hybrid x planting density was found on the total productivity of the water. In the grain yield, an effect of the interaction environment x hybrid, environment x density and hybrid x density was found. A highly significant effect was found on the hectoliter weight of the environment and the type of hybrid. The interaction of the Atziri Puma hybrid with the environments and with the planting density showed the maximum values of total water productivity and grain yield.
Show more [+] Less [-]Measurement of free water in foods by secondary derivative thermogravimetry | Medición del agua libre en alimentos mediante termogravimetría de segunda derivada Full text
2018
Wang, Yubin | Zheng, Qingyun | Li, Wu | Ma, Yue | Zhao, Xiaoyan | Zhang, Chao
Measurement of free water in foods by secondary derivative thermogravimetry | Medición del agua libre en alimentos mediante termogravimetría de segunda derivada Full text
2018
Wang, Yubin | Zheng, Qingyun | Li, Wu | Ma, Yue | Zhao, Xiaoyan | Zhang, Chao
The thermogravimetry (TGA) and derivative thermogravimetry (DTG) methods have been used to measure the free water in low-moisture foods. In this study, the 2nd derivative thermogravimetry (2nd DTG) method distinguished the free and bound water based on the speed of moisture evaporation, which could be used for both low-moisture and high-moisture foods. First, the key factors related to moisture evaporation were optimized. Isothermal temperature of 30 ~ 50°C, dynamic temperature of 0.033 ~ 0.133°C/min, and flow rate of nitrogen of 20 ~ 40 mL/min were the optimal parameters for the 2nd DTG method. Under these conditions, the repeatability and reproducibility of the 2nd DTG method were enhanced, its applicability was expanded to high-moisture foods, and the accuracy was ± 4.0% of the nuclear magnetic resonance results. Hence, the 2nd DTG method is better suited for the measurement of free water in foods.
Show more [+] Less [-]Measurement of free water in foods by secondary derivative thermogravimetry Full text
2018
Yubin Wang | Qingyun Zheng | Wu Li | Yue Ma | Xiaoyan Zhao | Chao Zhang
The thermogravimetry (TGA) and derivative thermogravimetry (DTG) methods have been used to measure the free water in low-moisture foods. In this study, the 2nd derivative thermogravimetry (2nd DTG) method distinguished the free and bound water based on the speed of moisture evaporation, which could be used for both low-moisture and high-moisture foods. First, the key factors related to moisture evaporation were optimized. Isothermal temperature of 30 ~ 50°C, dynamic temperature of 0.033 ~ 0.133°C/min, and flow rate of nitrogen of 20 ~ 40 mL/min were the optimal parameters for the 2nd DTG method. Under these conditions, the repeatability and reproducibility of the 2nd DTG method were enhanced, its applicability was expanded to high-moisture foods, and the accuracy was ± 4.0% of the nuclear magnetic resonance results. Hence, the 2nd DTG method is better suited for the measurement of free water in foods.
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