Tres años de ensayos de poda mecánica y manual en limonero Fino 95

La poda manual de limoneros en el sureste de España supone aproximadamente el 39% del total de los costes de mano de obra del cultivo. La poda mecánica se puede integrar en una estrategia de gestión del cultivo para reducir los costes de poda; sin embargo no es una técnica que está ampliamente aceptada entre los agricultores, entre otros motivos, por la falta de estudios rigurosos con variedades y formas de cultivo que justifiquen sus posibles ventajas. En este trabajo se exponen los resultados de una experiencia de tres años para evaluar el potencial de la poda mecánica combinada con poda manual en limoneros ‘Fino 95’. Los parámetros analizados han sido producción, calibre, calidad de la fruta, características de la biomasa podada y productividad de la labor. Se han realizado cinco tipos de tratamientos de poda: (1) poda manual (control) y cuatro intensidades de poda mecánica que tienen en común la poda de faldas y copa; y en las que la intensidad de poda mecánica se incrementó a medida que la intensidad de la poda manual se reducía; (2) poda mecánica de faldas y copa con repaso manual, (3) poda mecánica de faldas, copa y un lado del árbol; y poda manual del otro lado del árbol, (4) poda mecánica de faldas, copa y un lado del árbol, y (5) poda mecánica de faldas, copa y los dos lados del árbol. Estos tratamientos se han repetido durante tres años con alternancia de tipo de poda en el mismo bloque creando cinco tratamientos plurianuales. La principal conclusión del trabajo es que el tratamiento plurianual que alternó anualmente poda mecánica y manual, o bien el tratamiento de solo poda mecánica los tres años obtuvieron la mayor producción comercial acumulada. Por otro lado, los tratamientos con poda manual y mecánica el mismo año han obtenido la menor producción comercial acumulada

Sostenibilidad ambiental del riego con agua marina desalinizada y reutilización de drenajes en tomate bajo invernadero

La incorporación de agua marina desalinizada (AMD) al sureste español es la principal estrategia recogida en la planificación hídrica española con el fin de hacer frente a su déficit estructural de agua, que afecta principalmente al regadío. Este trabajo analiza la sostenibilidad medioambiental del riego con AMD en sistemas hidropónicos con reutilización de drenajes para el cultivo de tomate bajo invernadero. La metodología aplicada se basa en el Análisis de Ciclo de Vida (ACV) de acuerdo con la normativa ISO 14040. Esta metodología atribuye al producto final todos los efectos ambientales derivados del consumo de materias primas y de energías necesarias para su manufactura, las emisiones y residuos generados en el proceso de producción, así como los efectos ambientales procedentes del fin de vida del producto cuando éste se consume o ya no se puede utilizar. La metodología ha sido aplicada con los datos experimentales obtenidos mediante ensayos en el marco del proyecto LIFE-DESEACROP en la Fundación Finca Experimental UAL-ANECOOP, Retamar (Almería) y analiza específicamente y de forma comparativa los efectos de (1) las fuentes de agua convencionales frente al riego con AMD, y (2) los sistemas con reutilización de drenajes frente a los sistemas que vierten los drenajes al subsuelo. Los impactos ambientales analizados han sido el potencial de calentamiento global, el potencial de acidificación del suelo y el agua, el potencial de eutrofización, y el potencial de agotamiento de recursos abióticos. También se han incluido en el análisis dos indicadores de especial relevancia en la producción agrícola como la eficiencia del uso del agua y la demanda de energía acumulada. Como conclusiones del trabajo cabe destacar que, (1) el empleo de agua AMD supone un aumento leve del impacto ambiental en la mayoría de categorías de impacto analizadas (< 5%); (2) el cultivo hidropónico tiene una mayor eficiencia del uso del agua que el cultivo en suelo (14%) y (3) la reutilización de drenajes reduce la acidificación, eutrofización y agotamiento de recursos, pero aumenta el calentamiento global y la demanda de energía acumulada

Evaluación agronómica del riego con agua marina desalinizada en cítricos. Resultados del primer año de ensayo

La escasez de agua y la creciente presión sobre los recursos hídricos en regiones semiáridas ha fomentado la utilización de recursos hídricos no convencionales, como es el agua marina desalinizada (AMD). El AMD es un recurso hídrico inagotable y no sujeto a variaciones climáticas, por lo que estratégicamente resulta idóneo para aumentar la disponibilidad de agua para riego en zonas costeras deficitarias. Sin embargo, el AMD presenta una elevada concentración de Na, Cl- y B y una baja concentración de Mg, Ca y SO42-. Los escasos estudios realizados hasta la fecha en Israel y España sobre pimiento, banana y tomate, ponen de manifiesto que el riego con AMD, si no se realiza de forma adecuada, puede producir problemas agronómicos y afectar a la productividad de los cultivos. Por el contrario, manejada de forma adecuada puede incrementar el rendimiento y la eficiencia del uso del agua. Actualmente no existe información referente al efecto del riego de cítricos con AMD. Por esta razón, este estudio presenta los resultados agronómicos del primer año de investigación sobre los efectos del riego de un huerto de mandarinos con AMD. Los resultados indican que, a pesar de que las concentraciones de Na y B en el agua de riego y en las hojas han alcanzado los umbrales citados como tóxicos en la bibliografía, no se han observado fitotoxicidad por Na, Cl- o B en hoja. Además, tampoco se han observado diferencias significativas en rendimiento productivo, número de frutos y productividad del agua

Effect of mechanical pruning on the yield and quality of ‘Fortune’ mandarins

<p>This work compares mechanical pruning followed up by hand pruning versus manual pruning in the case of ‘Fortune’ mandarins. Yield and fruit quality were measured over a three-year period. Two mechanical pruning intensities were tested, these intensities being measured as the width of the row middles left free after mechanical pruning. Although there were differences in biomass and diameter of the branches that were cut, no differences were observed between the two mechanical pruning intensities in terms of yield or fruit quality. In all pruning treatments, fruit size reached the highest category. The pruning treatments consisted in: (i) hand pruning every year, (ii) mechanical pruning followed up by hand pruning every year, and (iii) alternating the two previous methods over the years studied. On analysing the accumulated fruit production of the three years, it can be observed that there were no significant differences in yield when mechanical pruning was alternated with hand pruning over the years. When only mechanical pruning was used for the three years, however, a 22% reduction in yield was observed with respect to the treatment involving hand pruning alone. From the economic point of view, mechanical pruning shortened the time needed to complete the follow-up hand pruning by 13% with respect to just hand pruning, but this reduction in labour does not offset the cost of the mechanical equipment.</p

Satellite-Based Method for Estimating the Spatial Distribution of Crop Evapotranspiration: Sensitivity to the Priestley-Taylor Coefficient

This work discusses an operational method for actual evapotranspiration (ET) retrieval from remote sensing, considering a minimum quantity of ancillary data. The method consists in a graphical approach based on the Priestley-Taylor (PT) equation, where the dry soil and non-limiting water conditions are defined by land surface temperature (LST) and vegetation index (VI) space, both retrieved from remote sensing. Using ET tower flux measurements and Landsat 5 TM images of an irrigation scheme in southeast Spain, a sensitivity analysis of ET spatial distribution was performed for the period 2009–2011 with respect to: (i) the shape (trapezoidal or rectangular) of the LST-VI space; and (ii) the value of the PT coefficient, α. The results from ground truth validation were satisfactory, both shapes providing similar performances in estimating ET, with root mean square error ~30 W/m2 and relative difference ~10% with respect to tower-based measurements. Importantly, the best fit with ground data was found for α close to 1, a somewhat different value from the commonly used value of 1.27, indicating that substantial error might arise when using the latter value. Overall, our study underlines the importance of a more precise knowledge of the actual value of α coefficient when using ET retrieval methods based on the LST-VI space

Influence of the Water Source on the Carbon Footprint of Irrigated Agriculture: A Regional Study in South-Eastern Spain

Curbing greenhouse gas (GHG) emissions to combat climate change is a major global challenge. Although irrigated agriculture consumes considerable energy that generates GHG emissions, the biomass produced also represents an important CO2 sink, which can counterbalance the emissions. The source of the water supply considerably influences the irrigation energy consumption and, consequently, the resulting carbon footprint. This study evaluates the potential impact on the carbon footprint of partially and fully replacing the conventional supply from Tagus–Segura water transfer (TSWT) with desalinated seawater (DSW) in the irrigation districts of the Segura River basin (south-eastern Spain). The results provide evidence that the crop GHG emissions depend largely on the water source and, consequently, its carbon footprint. In this sense, in the hypothetical scenario of the TSWT being completely replaced with DSW, GHG emissions may increase by up to 50% and the carbon balance could be reduced by 41%. However, even in this unfavourable situation, irrigated agriculture in the study area could still act as a CO2 sink with a negative total and specific carbon balance of −707,276 t CO2/year and −8.10 t CO2/ha-year, respectively. This study provides significant policy implications for understanding the water–energy–food nexus in water-scarce regions

Intercropping Practices in Mediterranean Mandarin Orchards from an Environmental and Economic Perspective

Crop diversification is becoming increasingly important for preserving soil and ecosystems&rsquo; health and, subsequently, crop productivity and sustainability. Intercropping practices adopted in monocultural woody crops, with herbaceous crops covering the otherwise bare alleyways, foster ecological interactions and can provide both environmental and economic advantages. In this study, intercropping practices were implemented in a traditional mandarin orchard in south-eastern Spain, which was monitored for three years to assess their impact on the environmental footprint and profitability. The footprint was quantified with a cradle-to-gate life cycle assessment (LCA), while the costs and revenues assessment was based on materials, labor, and machinery used in the trial. The calculated LCA indicators evidenced that, although the cultivated surface area increases with the integration of the intercrops (fava bean, purslane, cowpea, and barley/vetch mix), this does not imply any additional detrimental effects (resource depletion, acidification, eutrophication, global warming). The economic analysis showed that while intercrops may involve additional production costs, the correct choice of intercrops, purslane, and fava bean, in this case, can reduce the market risks for farmers. Overall, this study shows that positive environmental and economic impacts are to be expected of co-integrated herbaceous crops within the same field as mandarin trees

Intercropping Practices in Mediterranean Mandarin Orchards from an Environmental and Economic Perspective

Crop diversification is becoming increasingly important for preserving soil and ecosystems’ health and, subsequently, crop productivity and sustainability. Intercropping practices adopted in monocultural woody crops, with herbaceous crops covering the otherwise bare alleyways, foster ecological interactions and can provide both environmental and economic advantages. In this study, intercropping practices were implemented in a traditional mandarin orchard in south-eastern Spain, which was monitored for three years to assess their impact on the environmental footprint and profitability. The footprint was quantified with a cradle-to-gate life cycle assessment (LCA), while the costs and revenues assessment was based on materials, labor, and machinery used in the trial. The calculated LCA indicators evidenced that, although the cultivated surface area increases with the integration of the intercrops (fava bean, purslane, cowpea, and barley/vetch mix), this does not imply any additional detrimental effects (resource depletion, acidification, eutrophication, global warming). The economic analysis showed that while intercrops may involve additional production costs, the correct choice of intercrops, purslane, and fava bean, in this case, can reduce the market risks for farmers. Overall, this study shows that positive environmental and economic impacts are to be expected of co-integrated herbaceous crops within the same field as mandarin trees

Ion Exchange Resins to Reduce Boron in Desalinated Seawater for Irrigation in Southeastern Spain

Desalinated seawater (DSW) can provide water resources for irrigation in coastal regions where freshwater is scarce. Reverse osmosis (RO) is the most common technique to obtain DSW worldwide. Nevertheless, using DSW for irrigation could pose an agronomic risk as RO permeates may have a boron concentration above the phytotoxicity thresholds of certain crops, such as woody crops (0.5 to 1.0 mg/L). In this study, an on-farm ion exchange resin system with an average flow of 1 m3/h, designed to reduce the boron concentration of DSW, was evaluated from a technical and economic perspective. The impact of variations in the feed water and operating temperatures on the boron reduction process was assessed. The results show that the system can provide an outflow with a boron concentration below the threshold of 0.5 mg/L over 92 h of operation, with boron rejections of up to 99% during the first 41 h. The estimated cost of boron removal with the on-farm system of the trial was EUR 0.992/m3. However, this cost is expected to decrease to EUR 0.226/m3 for a commercial ion exchange resin (IX) plant (20 m3/h), highlighting the importance of the scale factor. Our results provide novel guidance on the viability of using boron removal IX systems for farms irrigated with DSW, when it is provided by coastal plants with boron concentrations above the crop tolerance