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Micro irrigation has been claimed to be the world's most valued irrigation innovation. However, both its potential to save water and its adaptability to smallholders’ needs are being questioned, while its energy requirement implies financial and environmental costs that are not affordable everywhere. This paper contributes to this debate with a field performance assessment of smallholder micro irrigation systems in the Baixo Acaraú Irrigation District, Ceará, Brazil, and a novel analysis model that depicts the energy-water-yield nexus by linking irrigation performance with energy efficiency and yield gap. Irrigation system performance was evaluated in a sample of 40 family lots and compared to design performance in a fairly homogeneous subset of them. Pumping inefficiency and inappropriate filtering have been at the root of system deficiencies. The great variability of irrigation performance indicated a wide margin for improvement and the possibility of using prominent farmers as benchmarks. Although there has been “technology translation” in the irrigation district that included local innovation in the filtering system, the process has not been completed. It is concluded that the adoption of foreign irrigation technology could be accelerated with the collaboration between local innovators and publicly-supported irrigation advisory services using integrated performance assessment approaches like the one presented here. [ABSTRACT FROM AUTHOR]

This paper examines the economic feasibility of a subsurface irrigation system for a representative corn producer in Norfolk County, Ontario, Canada. We use stochastic capital budgeting to generate a distribution of net present values for this investment. Future corn yields and corn prices were treated as distributions. Under our base assumptions, the subsurface drip irrigation system has a negative expected net present value, meaning that it would not be a worthwhile investment for a corn farmer at the present time. The system's ability to increase yields has the largest effect on its expected net present value. Attempts to improve the system's economic value should focus on increasing its effect on yields in years with typical agronomic conditions. With reasonable assumptions for other system parameters, the initial cost of a 40.5 ha system would have to be reduced to $165,000 to have a positive net present value 50% of the time or the system would have to increase corn yields by 33% in years with typical growing conditions to achieve the same net present value outcome. [ABSTRACT FROM AUTHOR]

Abstract: We discuss the role and characteristics of water markets in Australia in facilitating efficient water allocation. Administrative, regulatory and/or political barriers to effective functioning of water markets are reviewed with a focus on the southern Murray-Darling Basin (MDB) region of Australia. A mathematical model is developed to estimate the costs of existing restrictions and the benefits from potential changes in water markets (e.g., removing barriers in temporary water markets). The modelling results reveal that expanding trade leads to an increase in mean annual net returns from AU $2502 million to AU $2590 million (i.e., an increase of AU $88 million). When the current volume restrictions, exchange rates, and trading charges are accounted for, mean annual net returns reduced from AU $2590 million to AU $2573 million (i.e., a reduction of AU $17 million). The exclusion of any of the three southern MDB states from the interstate water trading imposes significant costs. If South Australia, New South Wales or Victoria withdraws from the water market, net returns are reduced by AU $27 million, AU $31 million and $63 million, respectively. The paper outlines the policy implications of strategies to remove market barriers and to facilitate efficient and effective water trading. [Copyright &y& Elsevier]