Design Versus Scheduling in Micro-irrigation Systems for Water-saving and Environmental Protection
Micro-irrigation can provide an irrigation water application with high uniformity. However, the uniformity alone will not be sufficient to achieve the goal of irrigation. The irrigation schedule is equally important in micro-irrigation practice. The efficient water use by micro-irrigation can be evaluated by the total return. An optimal irrigation schedule was determined through an economic analysis using the cost of water, price of yield, uniformity of the micro-irrigation system, crop response to water application and environmental concerns of pollution and contamination. Several irrigation schedules were compared with the optimal one. The optimal irrigation schedule can achieve optimal return and also provide water saving compared with the conventional irrigation schedule in which the whole field is fully irrigated. Deep seepage can be eliminated or minimized by scheduling deficit irrigation. The environmental protection irrigation schedule can save more water but will cause some total return reduction compared with optimal irrigation schedule. When there is an environmental concern in polluting nearby stream or underlying ground water, the environmental protection schedule will prevent the possibility of pollution. The simple irrigation schedule can even save more water compared with optimal solution, but will cause some total return reduction depending on the cost of water and cost remediation of environmental pollution. The simple irrigation schedule can achieve high application efficiency, more than 95％ , and cause only a small deficit , less than 5％ , when the system is designed for coefficient of variation less than 10％. This shows the significance of designing a high uniformity micro-irrigation system and the determination of correct adjustment for evapotranspiration. When a high uniform irrigation system is designed and used the difference among the specified irrigation schedules will be reduced. It is very simple to design a micro-irrigation system for coefficient of variation equal to or less than 10％. It can be done by selecting the emitters with a manufacturer s coefficient of variation less than 5％ and a coefficient of hydraulic variation of 8. 5％. In this case the coefficient of variation will be about 10％.
Deficit irrigation Croundwater contamination Optimal irrigation scheduling
J. Barragan L. L. Cots J. Monserrat I. P. Wu
Department of Agro-forestry Engineering, University of Lleida, Catalunya, Spain Department of Biosystems Engineering, University of Hawaii, Honolulu, Hawaii, 96822, USA
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
888-893
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）