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131.
ABSTRACT Concern over increasing water scarcity has led to the introduction of the concept of agricultural water productivity and an emphasis on interventions to achieve ‘more crop per drop’. Yet, a strong debate continues on how the concept is to be defined and used. Drawing largely from the irrigation literature, the origins of the concept and its methodological developments are reviewed, and its use in applied work over two decades is discussed. Based on this analysis of conceptual and applied research, key insights into the concept’s contributions and limitations are presented, as well as opportunities for further refinements. 相似文献
132.
Linda Estelí Méndez-Barrientos Jeltsje Sanne Kemerink Philippus Wester François Molle 《国际水资源开发杂志》2018,34(2):245-258
This article shows how large-scale commercial farmers, individually and collectively, are responding to land and water reform processes in the Thukela River basin, KwaZulu-Natal, South Africa. With a high degree of innovative agency, commercial farmers have effectively executed four strategies, enabling them to adapt and use their access to resources to neutralize multiple water reform efforts that once promised to be catalysts for inclusive change in the post-apartheid era. It is likely that policy alone will not facilitate the envisioned transformation, if local practices are not sufficiently understood and anticipated by the governmental officials charged with the implementation of water reform processes. 相似文献
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The catch can method is traditionally used for evaluating performance of drip systems. Two variations of this method are commonly applied in laboratory testing of drippers: the sequential and the simultaneous method. This study compared uniformity and measurement uncertainty of the two methods, with the overall aim of improving irrigation water management. The simultaneous method was found to have a lower coefficient of variation (Cv) and measurement uncertainty, indicating that it is more accurate than the sequential method. In all the tests, however, the Cv was determined to be <5%, which is acceptable as per the current reference standard. 相似文献
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An integrated low-cost adsorption (with powdered activated carbon, PAC) and cross-flow membrane filtration (with microfiltration membranes of 0.1 and 0.2 μm pore sizes) process was employed for the treatment of biotreated palm oil mill effluent (POME) to produce irrigation water that is fully benchmarked with water-quality standards. The permeate quality was within the recommended standard for irrigation water, as the concentrations of all critical constituents were well below their recommended values. Sustainability of the process integration was further confirmed with the domination of cake filtration over other blocking mechanisms with higher R2 values at all trans-membrane pressures. Suitable extended usage of permeate was found for toilet/urinal flushing. 相似文献
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Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study
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Ricardo Machado Alessandra Timponi Goes Cruz Bianca Marques de Mattos de Araujo Adriane Antoniw Klemz Hellen Pontes Klug Ulisses Xavier da Silva Neto 《Microscopy research and technique》2018,81(6):649-654
The aim of this study was to evaluate tubular dentin sealer penetration, comparing different final irrigation protocols using a conventional needle (CONV), EndoActivator system (EAS), EndoVac system (EVS), and ultrasound (PUI). Initially, fifty‐two first maxillary molars with a single canal in the palatal root, without abrupt curvatures, resorptive processes, or previous endodontic treatment were selected for this study. Then, the crowns were sectioned to obtain palatal roots 15 mm in length. The root canals were prepared with the ProTaper Universal System and irrigated with 5% NaOCl. Afterwards, the specimens were divided into four groups (n. 13), according to the final irrigation protocol: CONV, EAS, EVS, and PUI. After filling, slices at 3 mm and 5 mm from the apex were obtained for analysis by confocal laser scanning microscopy. Two‐way comparisons between the groups and the levels were performed with Games Howell's test (p < .05). Tubular dentin sealer penetration was higher at 5 mm compared with 3 mm from the apex (p < .05). The EAS group showed a higher percentage of tubular dentin sealer penetration, compared with the CONV group, at both levels. At 3 mm, there was no statistically significant difference among EAS, EVS, and PUI; however, these groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with the other groups. 相似文献
140.
文章介绍了采用地表水与地下水联合调度,将河水与井水两者有机地结合起来,建立一种农业灌溉水资源开发利用模式,实现农业可持续发展与保护生态环境并举。 相似文献