جستجوی مقالات مرتبط با کلیدواژه « maintenance » در نشریات گروه « آب و خاک »

Use of nitrate fertilizer to increase crop yield is a method used by many farmers. Once this ion enters the soil, it is converted to nitrate and easily leached. Using zeolite is one of the methods to prevent nitrate leaching has received much attention today; however, determining the exact amount of nitrate fertilizer when using zeolite is very important. Performing experiments in a classic way and taking into account the effect of all factors (factorial design) needs time and cost in performing experiments. For this reason, old research methods should be replaced by simple and standard methods such as Taguchi and central composite design. For this purpose, this study was conducted in a completely randomized as factorial design. Treatments consisted of zeolite (at three amount; zero, 2 and 6%) and nitrate application (at three levels; zero, 200 and 400 mg nitrate per kg of soil) with three replications. Taguchi and central composite designs were considered with 9 and 13 experiments, respectively. The results of complete factorial method showed that the amount of zeolite had a significant effect on nitrate leaching; however, nitrate fertilizer had no effect on nitrate leaching. According to Taguchi results, both zeolite and nitrate fertilizer were very important on nitrate leaching reduction from soil. Based on prioritizing the effect in the central composite design, it was observed that zeolite was the most important factor in reducing nitrate leaching. Based on the results, the application of 2% zeolite was the beginning of the effect of zeolite on nitrate leaching. Therefore, it can be expected that in amounts between 2 to 6% zeolite, a significant reduction in nitrate leaching occurs.

Paddy fields development and renovation as the most important project to improve infrastructures of the rice sustainable production in North of Iran have had very slow Implementation pace due to various reasons and so that the project has been executed in less than 60000 hectares out of total paddy fields in Mazandaran province. Therefore, identification and prioritization of design, execution and operational problems is the basic requirements to change the existing situation. this research consider comparative comparison method between the design and as-built drawings, field monitoring of operating difficulties as well discussion and interview with experts. Then finalized list of problems, which used to develop a questionnaire with seven inquiries based on the Analytic Hierarchy Process (AHP). It contains four main indicators employers’ arrangements, design, execution and finally, operation and maintenance. So, 35 experts of paddy fields Development and Renovation were selected (from Jihad-e-Agriculture Organization, consulting engineers and the contractors) to fill out the questionnaire. The results indicate the fundamental limitations in order of priority are: failure to provide the timely required credits, the lack of integrated viewpoint on irrigation and drainage studies, the lack of f operational organizations same as agricultural NGOs, deficiencies in farmers training which needs for proper operation and maintenance of the projects and legal problems especially when private property is incompatible with the public profits. Therefore, serious offers of this research are change in the financing method of the projects, for example e use of combination of native and foreign countries finance, build of all layout components of project and use of other constructing project procedures such as EPC (Engineering Procurement Construction).

Micro irrigation system is widely used to improve water use efficiency and water supply in most crop¡ especially vegetable and fruit crops. The micro irrigation system offers the highest irrigation uniformity compared with other irrigation systems. This irrigation systems can deliver water and nutri ents in precise amounts and at controlled frequencies directly to the plant’s root zone. The major cause of failure in micro-irrigation systems is emitter plugging. Emitter plugging can severely degrade irrigation system performance and application uniformity. Because the emitters are small and can easily plug¡ it is important to understand the filtration and maintenance requirements of these systems and be proactive to prevent plugging. Plugging hazards for micro-irrigation systems fall into three general categories: physical (sediment)¡ biological or organic (bacteria and algae)¡ and chemical (scale). Frequently¡ plugging is caused by a combination of these factors. The type of emitter plugging problems will vary with the source of the irrigation water. It is important to prevent plugging problems before they occur. The best prevention plan includes an effective filtration¡ water treatment¡ and maintenance strategy. A water analysis is vital to the proper design and opera tion of the micro-irrigation system. To assess irrigation system performance and to ensure that components like filters are working correctly¡ flow meters and pressure gauges must be properly installed to provide feedback to the system operator. Monitoring flow meters and pressure gauges over time can reveal system performance anomalies that may require attention. To prevent the accumulation of those contaminants and the resulting emitter plugging¡ flush the system periodically. Regular flushing is critical to system health and longevity. If the micro-irrigation system is equipped with a method for chemically treating the water source (most will be)¡ backflow protection¡ and other safety provisions¡ are necessary.

The main purpose of this research was to study development strategies of implementation of agricultural water management technologies from the perspective of farmers This research was a sort of survey studies and a questionnaire was used for collection of data and information. Questionnaire''s reliability was confirmed through computing cornbanch''s Alpha coefficient which was more than 0.70. Face validity of questionnaire was confirmed by a panel of expert judgment. Statistical population of this study was consisted of 20156 farmers; out of which 205 people were selected as sample using multi-stage sampling technique. Accordingly¡ lining along the irrigation channels¡ promoting the pumps to electrical type¡ prevention of leakage from the gates¡ education of the farmers for operation and maintenance of the pumps¡ and observation of distance between the wells are priorities for development of the technology for agricultural water managements. Also factor analysis results of reception of farmers to alternative of development of agricultural water management technologies application revealed six factors totally they explained 65.28 percent of total variance.

Water user's participation in agricultural water projects is necessary for proper operation and maintenance of irrigation and drainage systems and it is one of the most important issues in development of growing communities. In Alborz Integrated Land and Water Management Project (AILWMP), due to the strategic policies and the support of the World Bank, a key goal of the project is the formation of Water Users’ Associations (WUAs). The sample population of this study was 103 board members of 19 WUAs within the AILWMP area in Mazandaran province. Field data collection instrument was a questionnaire which was validated using Cronbach– alpha, calculated at 0.73. To design the questionnaire, the Delphi method was used and, to evaluate the effective components, ten categories were determined and weighted. The first priority was sustainability, which was the main goal of the organization based on the project document. Necessity of organizing the WUA as well as education and information dissemination indexes were the second priority. Task definition and satisfaction indexes were considered as the third priority. To ensure the accuracy of answers, the questionnaire used active researchers approach. The research results showed that, up to this stage, WUA's progress have been fairly successful. The effective indexes of WUAs’ success were identified as information and training, the need to create association, roles definition, and sustainability, with respective weights of 0.326, 0.292, 0.266, and 0.239. Therefore, these components must be implemented carefully in future projects to achieve successful WUAs.