A growing international human population and rising living standards are increasing the demand for agricultural products. Under higher pressure over natural resources, environmental concerns are increasing as well, challenging current water use decision-making processes in irrigated agriculture. Higher agricultural productivity means water should be applied more efficiently, which requires instant information on weather, soil, and plant conditions throughout the growing season. An information-based irrigation scheduling application tightened to the spatiotemporal variability of the fields is critical for enhancing the current irrigation system and making better irrigation scheduling decisions. The aim of this study is to review current irrigation scheduling methodologies based on two case studies (woody and field crops) located in semi-arid areas of Southeast Spain. We realize that optimal irrigation programming requires consistent investment in equipment, expenditure on operation and maintenance, and qualified technical and maintenance services. These technological approaches will be worthwhile in farms with low water availability, high profitability, and significant technical-economic capacity.

The companion paper presented a self-programmable profit-oriented irrigation scheduling strategy based on simulation models. This study is an assessment of the strategy and aims to contribute to the analysis of its viability. The assessment is based on the simulation of corn irrigated with a typical solid-set system under 81 scenarios that combine different conditions of weather, soil, and prices over a period of nine years. Two simpler self-programmable yield-oriented strategies serve as benchmarks for the assessment. The profit-oriented strategy achieves up to 168 euros/ha higher profit, depending on the conditions of the scenario. Lower percolation and better harnessing of initial soil water are the main drivers of the profit gap, in which the influence of prices is low because of the high efficiency achieved. This water conservation (up to 128 mm) could also deliver additional benefits that future researches should analyze. The models and a multidisciplinary approach provide a better understa...

Liberalization of agricultural markets is changing the irrigation focus from maximizing yields to maximizing profits. This study was conducted to develop a self-programmable irrigation scheduling strategy for solid sets aimed at improving profits. It is based on simulation models and water and crop prices. The economic optimization of solid-set irrigation is constrained by the fact that the efficiency is not previously known because of the unpredictability of seasonal weather and the accumulated effect of nonuniform irrigations in the soil water depletion (SWD) uniformity. Consequently, seasonal revenue and cost functions cannot be determined. The strategy addresses this constraint by (1) refilling SWD under weather conditions that minimize water losses when crop is not water stressed and SWD is high and uniform enough to prevent percolation; and (2) estimating revenue and cost functions for each irrigation event in order to determine the economically optimal water depth when SWD uniformity is so ...

A surface irrigation evaluation process in an irrigation project requires expensive field work. Models that reproduce irrigation events help to analyse the data obtained, and evaluate different scenarios of improvement. The use of combined models that reproduce the interaction between irrigation water and the conveyance and drainage network, agricultural production, and the environment can increase the productivity of the field work. Their results surpass the analyses based only on application efficiency, and provide a wide range of irrigation, hydrological and economic indicators. The application of one of these models (Ador-Simulation) in a study area of the Bear River irrigation project (UT) showed that an increase in irrigation efficiency from 56 to 77 % can be achieved optimizing current irrigation time. This results in a 27 % of water saving over the 2008 demand, and in a little increase in current low economic productivities.