Laboratory evaluation of dripper performance

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 (C_v) and measurement uncertainty, indicating that it is more accurate than the sequential method. In all the tests, however, the C_v was determined to be <5%, which is acceptable as per the current reference standard.     

一种适用于屋面绿化的种植层结构

针对屋面绿化的种植层容易流失的情况，介绍了一种适用于屋面绿化的种植层结构，通过增设围护结构，提供了一种有效阻止种植基质流失的方法，同时又不影响整体景观效果。     

Studies on pore blocking mechanism and technical feasibility of a hybrid PAC-MF process for reclamation of irrigation water from biotreated POME

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.     

雾化布液堆浸某铀矿石的柱浸试验

采用雾化布液新工艺,进行了某铀矿石的小型室内柱浸试验,并对雾化、喷淋、滴淋3种布液方式作了对比。结果表明,雾化布液的均匀性好,矿堆无板结现象,矿石浸出性能较好,浸出周期缩短,液固比小,适宜于某铀矿石的处理。     

堆浸雾化布液条件实验研究

布液是堆浸浸出工艺中一个重要环节之一。本文介绍了一种新的布液方法——雾化布液。用铀矿石模拟矿堆，通过堆浸雾化布液条件实验，得出使用该布液法能得到较高的浸出液铀平均浓度及较高的浸出率，能缩短浸出时间，提高经济效益，从而验证了雾化布液的优越性。为堆浸矿山采用雾化布液提供参考依据。     

Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study

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.     

Grasses for biofuels: A low water-use alternative for cold desert agriculture?

In arid regions, reductions in the amount of available agricultural water are fueling interest in alternative, low water-use crops. Perennial grasses have potential as low water-use biofuel crops. However, little is known about which perennial grasses can produce high quantity, high quality yields with low irrigation on formerly high-input agricultural fields in arid regions. We monitored biomass production, weed resistance, rooting depth, and root architecture of nine perennial grasses under multiple irrigation treatments in western Nevada. Under a low irrigation treatment (71 ± 9 cm irrigation water annually), cool-season grasses produced more biomass and were more weed-resistant than warm-season grasses. With additional irrigation (120 ± 12 cm water annually), warm- and cool-season grasses had similar biomass production, but cool-season species remained more weed-resistant. Among species within each grass type, we observed high variability in performance. Two cool-season species (Elytrigia elongata and Leymus cinereus) and one warm-season species (Bothriochloa ischaemum) performed better than the other tested species. Root depth was not correlated with biomass production, but species with deeper roots had fewer weeds. Abundance of fine roots (but not large roots) was correlated with increased biomass and fewer weeds. Both L. cinereus and E. elongata had deep root systems dominated by fine roots, while B. ischaemum had many fine roots in shallow soil but few roots in deeper soil. Cool-season grasses (particularly E. elongata, L. cinereus, and other species with abundant fine roots) may be worthy of further attention as potential biofuel crops for cold desert agriculture.     

Irrigation Development and Rural Poverty in Gujarat,India: A Disaggregated Analysis

Abstract

There has been renewed interest during recent times in the impact of irrigation development on rural poverty. For long, researchers asked whether irrigation development reduces the poverty of irrigators. However, the question being asked now is: does investing in irrigation—rather than in other public works—help reduce rural poverty in a region? Using Government of Gujarat's 1997 census of Below Poverty Line (BPL) households as well as the Village Amenity Survey of the same year, this paper explores the interplay between irrigation development and rural poverty in 177 predominantly rural talukas, which is an administrative unit with a population of around 100,000-150,000 people, of Gujarat state in western India. Our analysis shows that for the design of poverty-targeting programs, two variables have the highest appeal: primary education infrastructure and improved land productivity through irrigation. It also suggests that, over the long run, irrigation benefits far transcend the command areas of irrigation systems. As a result, irrigation impact studies focused at farm or command area level seriously underestimate overall livelihood impacts of irrigation development. This is because intensively irrigated areas act as magnets that attract rural poverty from their surround, especially from other dry areas. Population pressure on farm lands thus tends to get redistributed according to the carrying capacity of farm lands. Across 177 predominantly rural talukas of Gujarat, we find: a) an inverse relationship between land use intensity and land-man ratio; and b) as land productivity (output/hectare of net sown area) declines, output per rural person declines too, but far more slowly than would have been the case without the “magnet effect.”     

Fertigation in Furrows and Level Furrow Systems. II: Field Experiments, Model Calibration, and Practical Applications

Furrow fertigation can be an interesting practice when compared to traditional overland fertilizer application. In the first paper of this series, a model for furrow fertigation was presented. The simulation model combined overland water flow (Saint-Venant equations), solute transport (advection-dispersion), and infiltration. Particular attention was paid to the treatment of junctions present in level furrow systems. In this paper, the proposed model is validated using five furrow fertigation evaluations differing in irrigation discharge, fertilizer application timing, and furrow geometry. Model parameters for infiltration and roughness were estimated using error minimization techniques. The error norm was based on observed and simulated values of advance time, flow depth, and fertilizer concentration. Model parameters could be adequately predicted from just one discharge experiment, although the use of more experiments resulted in decreased error. The validated model was applied to the simulation of a level furrow system from the literature. The model adequately reproduced irrigation advance and flow depth. Fertigation events differing in application timing were simulated to identify conditions leading to adequate fertilizer uniformity.     

Allocation of Flow to Plots in Pressurized Irrigation Distribution Networks: Analysis of the Clément and Galand Method and a New Proposal

This article reviews the method for allocating flow to irrigation plots proposed by Clément and Galand in (1979). Mention is made of its shortcomings, such as the lack of consideration given to the specific technical and economic factors governing current pressurized (drip or sprinkler) irrigation systems and how they provide water to plots. We propose a method for fixed irrigation systems, which takes into account the irrigation method on the plot and the existence of an optimum block area. The result is to allocate a constant flow of water to plots up to an established value of maximum surface area. From there on, we propose applying linear increases related to the total plot area. We also present a formula for calculating the maximum number of blocks based on variables that are easily obtainable during the project phase.