MOPECO Model Research Articles

Determining Irrigation Requirements of Extensive Crops Using the Typical Meteorological Year Adjusted to the Growing Cycle Period

In the Castilla-La Mancha (CLM, Spain) region, most of the irrigated area is managed by two different strategies in which the previously defined irrigation requirements of crops affect both the distribution of crops and the sustainable management of groundwater resources. Thus, in the western Mancha system, the amount of irrigation water per farm is limited, while in the eastern Mancha system the irrigable area per farm is limited. Therefore, the use of average irrigation requirements in these areas may cause yield drops in dry years and the overuse of groundwater. Consequently, the main aim was to achieve a better approach to the irrigation requirements of the main extensive crops in CLM (maize (Zea mays L.), onion (Allium cepa L.), garlic (Allium sativum L.), and barley (Hordeum vulgare L.)) to help farmers and water authorities achieve higher yields and a more sustainable use of water resources. The typical meteorological year (TMY) methodology combined with the MOPECO model were used to: (1) determine the distribution of wet, intermediate, and dry years during the growing cycle of the four selected crops; (2) determine the average (AVE) and typical irrigation requirements of these crops for the complete 70 years series (TMYG) or the duration of the crop cycle (TMYC), and under wet (TMYW), intermediate (TMYI), and dry (TMYD) year conditions; and (3) recommend the irrigation depths to be used for the management of farms and water bodies. The results show that the number of wet, intermediate, and dry years depends on the growing cycle of the crop considered, with wet years being unusual, although they notably increase the average rainfall in the area. The irrigation requirements for the average year were between 20.4 and 9.0% lower than the average irrigation requirements calculated for the four studied crops during the 70 years of the series. For western Mancha farmers the recommended irrigation depth for dry years and most profitable crops (garlic and onion) is the one calculated for the driest year of the series, while for the rest of the years and crops is that estimated by the global dry TMY (TMYGD). For eastern Mancha farmers the recommended irrigation depths are also those estimated by the TMYGD.

Improving the Sustainability and Profitability of Oat and Garlic Crops in a Mediterranean Agro-Ecosystem under Water-Scarce Conditions

In areas with scarce water resources, population growth and climate change scenarios will mean that there is increasingly less water available for agricultural activity. Thus, optimizing crop irrigation water management is an absolute necessity. To address this situation, the SUPROMED project (sustainable production in water-limited environments of Mediterranean agro-ecosystems), available in an online platform, brings together a series of models and methodologies designed to promote more efficient management of water, energy and fertilizers. A two-year trial (2020–2021) was implemented in the Castilla-La Mancha region (Spain), with the aim of showing the effectiveness of SUPROMED as a farm management support tool. The trial was conducted on two of the region’s most important crops (oats and garlic). A series of productive, economic, and environmental key performance indicators (KPIs) were analyzed to measure the impact of transferring MOPECO (model for the economic optimization of irrigation water use at farm level), the irrigation scheduling model integrated in the SUPROMED platform, to farmers. In 2020, the management plan proposed by SUPROMED achieved a higher yield for oat than that generated by traditional management, using 40% less water. In the case of garlic, the same yield was obtained, using 30% less water. Gross margin and gross economic irrigation water productivity were improved for both crops. In 2021, one of the selected farmers was trained to use the SUPROMED platform to work with garlic crop. This management improved most of the KPIs analyzed compared to previous management without the SUPROMED platform, obtaining similar results to those obtained by SUPROMED in 2020. The results demonstrate that the tools and models included in SUPROMED have been properly adapted and can be easily used by farmers, improving the economic and environmental sustainability of Mediterranean agroecosystems.

Sustainable Production of Barley in a Water-Scarce Mediterranean Agroecosystem

Scarcity of water resources is one of the main constraints on agricultural activity in arid and semi-arid areas. Despite the great technological development over recent decades, farmers are demanding methodologies and tools adapted to their training, management restrictions, and economic capacity. To tackle these challenges, the sustainable production in water-limited environments of Mediterranean agroecosystems (SUPROMED) project combines, in an online platform, a set of models and methodologies for more efficient management of water, energy, and fertilizers. A two-year trial (2020–2021) was conducted in the Castilla-La Mancha region (Spain) to demonstrate, for a barley crop, the effectiveness of SUPROMED as a farm management support tool. The impact of transferring the model for the economic optimization of irrigation water use at farm level (MOPECO model) irrigation scheduling among other methods and tools, integrated in the SUPROMED platform, to farmers was determined by analyzing a set of productive, economic, and environmental key performance indicators (KPIs). The KPIs were selected to show farmers how the efficient use of productive factors could improve the profitability of their farms, thus reducing the impact of agriculture on the environment. In 2020, the management plan proposed by SUPROMED achieved the same yield as traditional management using 32% less water and resulting in a 13% and 66% improvement in gross margin and gross economic irrigation water productivity, respectively. In 2021, the management implemented by a farmer trained in the use of the tools and methodologies in the SUPROMED platform showed improvements in most of the KPIs analyzed, achieving similar results to those obtained by SUPROMED during 2020. The results are promising, indicating that the tools and models proposed in SUPROMED can be easily used by farmers and can improve the economic and environmental sustainability of Mediterranean agroecosystems. The involvement of public administrations, together with local researchers and technicians, is required for the effective promotion and use of these methodologies by the productive sector.

Análisis del comportamiento de una red colectiva de riego considerando la programación de riego en parcela

<p>El objetivo del trabajo es implementar una herramienta de simulación para la gestión de una red colectiva de riego, que minimice el coste energético en la estación de bombeo. La metodología propuesta ha sido aplicada en el año 2015 a una red de riego de 550 ha en Castilla–La Mancha para dos manejos de la presión en cabecera (fijo o variable), según el conjunto de tomas abiertas y su localización en la red. La herramienta simula el comportamiento de la red utilizando EPANET® partiendo de la programación de riegos de los cultivos del conjunto de parcelas abastecidas por la red utilizando el modelo MOPECO. Los resultados indican que la simplicidad de la gestión de la red con altura de presión fija hace que este sistema sea más interesante que con altura variable, a pesar del ligero incremento de consumo de energía que conlleva, inferior al 2% en los casos analizados.</p>

Regulated deficit irrigation strategies for different potato cultivars under continental Mediterranean-Atlantic conditions

This paper presents the calibration and validation processes of the MOPECO model for the simulation of 4 commercial potato cultivars (Zorba, Mirari, Monalisa and Leire), using the data from a three-year field experiment (years 2010, 2011 and 2012; two per cultivar) under deficit irrigation conditions in the Basque Country region of Spain. The optimized regulated deficit irrigation (ORDI) strategy was used in combination with the typical meteorological year (TMY) methodology to determine irrigation strategies aimed at increasing the irrigation water productivity of potato crop under real farming conditions and limited volumes of irrigation water. The growing degree-days for the whole growth cycle were 1958 °Cd, while the calibrated crop yield response (Ky) values for the growth stages proposed by FAO-56 were 0.45 (vegetative period), 0.70 to 0.90 (yield formation), and 0.25 to 0.40 (ripening) depending on the considered cultivar. The validation results showed that MOPECO is suitable for simulating the yield versus total water (gross irrigation + effective rainfall) use under the climatic and soil conditions in this study (normalized root mean square error from 7.2 to 8.5% between observed and simulated levels). ORDI maximized the yield of the crop for different volumes of available irrigation water. The irrigation water productivity differed according to the cultivar, increasing for lower volumes of irrigation water (from 23.0 kg m−3 to 58.1 kg m−3 for Monalisa and Mirari cultivars, irrigated with 100% and 40% of the requirements, respectively).

Model for management of an on-demand irrigation network based on irrigation scheduling of crops to minimize energy use (Part II): Financial impact of regulated deficit irrigation

The aim of the GREDRIP model (Part I) is to provide centralized management of an irrigation network, with a minimum energy cost at the pumping station, based on irrigation scheduling to guarantee crop water requirements in the irrigation network. In this paper, the combined use of GREDRIP and MOPECO models was used to improve water and energy consumption by applying Regulated Deficit Irrigation (RDI) to crops in the SORETA irrigation network (Albacete, Spain) for crop distribution and weather conditions during irrigation seasons 2015 and 2016. The MOPECO model was used to determine irrigation schedules and to estimate the relationship between irrigated crop yield and net water applied. The aim of this paper was to validate the GREDRIP model under different water demand conditions, and to study the financial impact on the irrigation network under drought conditions. Results show that GREDRIP is suitable for management of an irrigation network such as SORETA, reducing the energy cost by 32%, in comparison with the current situation. The financial analysis carried out shows that a 25% reduction in water consumption would have reduced the gross margin (GM) in SORETA by 30% (from 1199 to 839 € ha−1) in 2015 and 16% (from 914 to 771 € ha−1) in 2016, when RDI is applied to all crops. When RDI is only applied to less profitable crops (extensive herbaceous but not horticultural crops such as onion or garlic), a GM reduction of only 9% is obtained under 2015 and 2016 conditions, respectively. The water saved could be used for other purposes, such as increasing the crop area with higher GM, or simply to recharge the aquifer at risk of overexploitation, which would greatly benefit the environment. The combined use of GREDRIP and MOPECO can help to improve water and energy management in irrigation networks through crop irrigation scheduling. This can increase the profitability of agriculture by analyzing the financial effects of different irrigation management systems.

Effective management of irrigation water for carrot under constant and optimized regulated deficit irrigation in Brazil

The optimized regulated deficit irrigation (ORDI) determines the level of deficit (ratio between actual and maximum evapotranspiration “ETa/ETm”) to be applied at each development stage of a crop in order to reach the maximum yield for a certain global deficit at the end of the cropping period. One of the weaknesses of this methodology is its inability to forecast the effect of deficit irrigation on the quality of the harvest, which may affect the profitability of the crop. A research conducted in Seropédica (Brazil) during 2013 and 2014, aimed to assess the effect of deficit irrigation on the yield, quality, water productivity, and profitability of a carrot crop “Brasilia cv.”. Ten strategies of irrigation management were applied to the crop: full irrigation, 90, 80, 70, and 60% of ETm using constant deficit irrigation (CDI) (the ETa/ETm ratio was the same at all the development stages), 90, 80, 70, and 60% of ETm using ORDI, and rainfed. The experimental design was composed of random blocks equipped with a drip irrigation system. The moment and the amount of water applied to each treatment were determined by the soil water balance module of the MOPECO model, and corroborated by the monitoring of soil moisture samples. “Full irrigation” treatments achieved the highest yield, quality, and profitability per unit of the cropped area, while ORDI increased the water productivity and reached the highest profitability per unit of volume of irrigation water supplied to the crop (average up to 12.26€m−3 for the “0.6 ORDI” treatment vs. 8.38€m−3 for the “full irrigation”). CDI and ORDI treatments reached similar total yields. However, the marketable yields were 26.6% average higher for ORDI, advising against using the CDI strategy. Consequently, in areas where water is not scarce, the use of regulated deficit irrigation strategies is not justified. Nevertheless, in areas where water is the limiting factor, but not the irrigable land, ORDI may increase the total gross margin of a farm by supplying the same volume of irrigation water to a greater area.

Real farm management depending on the available volume of irrigation water (part I): Financial analysis

The MOPECO model tries to maximize the gross margin of farms through a more efficient use of both the irrigable land and the irrigation water. The objective of this work was to compare the profitability of a real irrigation farm managed following two different strategies. The Traditional strategy (T) consisted in applying full irrigation (F treatments) to a distribution of three crops (barley, maize, and onion) considering several volumes of irrigation water (from 1000 up to 8000m3ha−1) and four scenarios of harvest sale price. Depending on the availability of irrigation water, the MOPECO strategy (M) consisted in applying to the same crops full irrigation or the combinations of water deficit per growing stage determined by the optimized regulated deficit irrigation (ORDI) methodology developed for this model (O treatments). The optimal global deficits calculated by MOPECO for these crops were: 70% ETm for barley, 90% ETm for maize, and 90% ETm for onion. The experiment was conducted during years 2014 and 2015 in the semiarid province of Albacete (Spain). For low availabilities of irrigation water (between 2000 and 5000m3ha−1) the M strategy reached a profitability up to 8.2% higher than T in the most favorable scenario. This value is similar to the predicted by MOPECO for the average conditions of the area. In the rest of scenarios, the profitability was lower than expected due to the drought conditions of the two experimental years, the unfavorable climatic conditions during 2015 for onion and maize, and the prices progression during both seasons. MOPECO may also be used for decreasing the amount of pumped water from the aquifer (around 43.9hm3year−1 for average conditions), achieving the same profitability than the T strategies.

Real farm management depending on the available volume of irrigation water (part II): Analysis of crop parameters and harvest quality

The aim of MOPECO model is to maximize the gross margin of irrigated farms by a more efficient use of both the irrigable land and the irrigation water. One limitation of this model is its inability to simulate the effect of deficit irrigation on the quality of the harvests, which may affect the price perceived by the farmers. During the experiment, a farm located in Albacete (Spain) was managed by two different strategies during years 2014 and 2015. In the first strategy, the distribution of crops composed of barley, maize and onion was managed applying full irrigation (F). In the second strategy, crops were irrigated applying full irrigation or the optimized regulated deficit irrigation (O) methodology developed for MOPECO, depending on the available volume of irrigation water. The deficit levels determined by the model for reaching the maximum profitability were 0.7 of maximum evapotranspiration (ETm) for barley, and 0.9 ETm for maize and onion. The aim was to analyze the effect of the O methodology on the water productivity of the crops, on the quality of the harvests, and to determine if the O treatments would be economically penalized with regards to the F treatments due to quality drops. Hence, the O treatments reached a higher water productivity in terms of total dry biomass (average increase: 0.68kgm−3 for barley, 0.15kgm−3 for maize, and 0.01kgm−3 for onion) and dry yield (average increase: 0.26kgm−3 for barley, 0.08kgm−3 for maize, and 0.03kgm−3 for onion). The quality of the harvests and the significant differences found in this study (weight of barley and maize grains, and calibres size of bulbs in onion) did not affect the price perceived by the farmer. Due to this, the O strategy reached a higher profitability than F in the scenarios with lower availability of irrigation water (≤5000m3ha−1) (Part I). Therefore, the use of MOPECO at great scale may increase the profitability of farms located in water scarcity areas through a more efficient use of land and irrigation water.

Development of a direct-solution algorithm for determining the optimal crop planning of farms using deficit irrigation

The irrigation farms placed in areas of scare water demand methodologies that can increase their profitability via more efficient use of their resources. Determining the combination of factors that maximizes the profitability of any productive process requires the use of optimization methodologies. Traditionally, these types of problems were solved using heuristic methods. However, a direct-solution algorithm would produce faster and more accurate solutions. The aim of this work was to develop a direct-solution algorithm capable of determining the crop planning (area and volume of water per crop) that maximizes the profitability of an irrigation farm. The data required by the algorithm include the total cultivable area of the farm and the amount of available irrigation water as well as the “gross margin vs. irrigation depth” functions of the considered crops. Cultivating one or two crops is the way to reach higher profitability, but this strategy is not suitable from an agricultural point of view (i.e., crop rotation, diseases, weather risks, regulations of agricultural policies, etc.). Due to this algorithm must be compatible with the MOPECO model, a methodology has been developed to allow its implementation in this model. The objective of this software is to maximize the profitability of irrigation farms by incorporating a more efficient use of irrigation water using regulated deficit irrigation techniques. The current version of this model uses genetic algorithms for determining optimal crop planning, which are time consuming. For a hypothetical 100ha farm, considering 10 different crops and 11 scenarios of water availability, the developed algorithm adapted to MOPECO achieved gross margins around 0.5% lower than LINGO, and 1.1% higher than genetic algorithms, decreasing the calculation time requirements by between 50 and 100 and approximately 2000 times, respectively. Another relevant result is the fact that the algorithm may be used manually, by drawing the tangent lines between the gross margin curves, for reaching the optimal combinations of irrigation depth and, indirectly, the cultivable area of each crop. Moreover, the algorithm allows to understand the relationships among crops, which may advise users in the determination of the optimal solution under real conditions. This methodology also highlights the importance of using regulated deficit irrigation techniques when managing irrigation farms with a low supply of irrigation water. The developed algorithm may also be useful in the optimization of other production processes.

Modelling sustainable salt water management under deficit irrigation conditions for melon in Spain and Brazil.

In water scarcity areas the use of saline water for irrigation is a common practice. In this study, experimental data from two two-year melon tests were collected for the calibration (2004 'Yellow Melon' (YeMe) type) and validation (2002 YeMe, 2005 and 2006 'Piel de Sapo' (PiSa) type) processes in melon crop simulation under deficit irrigation conditions using salt water. The simulations were carried out for Castilla-La Mancha (Spain) and Ceará (Brazil) using the MOPECO model, which includes optimized regulated deficit irrigation (ORDI) methodology. The objective was to determine the most suitable irrigation strategy for both areas. Under fresh water conditions, ORDI may increase yield by up to 20% (PiSa) and 7% (YeMe) compared with constant deficit irrigation. Higher water deficit should be induced during the vegetative development and ripening stages. The rainfall between irrigation periods is able to leach the salts supplied by the irrigation water. The combination of ORDI with different strategies for managing saline water may increase water use efficiency. In these areas it may be of interest not to apply the leaching fraction (saving up to 67% of irrigation water). However, leaching of the soluble salts accumulated before starting the most sensitive periods may be suitable.

Combination of sowing date with deficit irrigation for improving the profitability of carrot in a tropical environment (Brazil)

This study was conducted to determine the most suitable irrigation strategy for improving the water productivity of carrot in Rio de Janeiro (Brazil) by using two sowing dates (June 16th and August 3rd). Experimental data from a two-year field test were used for calibration (2010) and validation (2011) of the simulation of carrot with the MOPECO model under deficit irrigation conditions. In 2010 and 2011 for no-deficit conditions the net irrigation was around 150 and 180mm in the 1st and 2nd sowing date, respectively. The maximum yield was about 64,000kgha−1. The root mean square error (2790 and 2968kgha−1) and the relative error (5.3 and 4.9%) values show good fit between the simulated and observed treatments for 2010 and 2011, respectively. Depending on the water stress target, the use of the optimized regulated deficit irrigation in the study area would increase carrot yield by up to 7% and 15% compared with the a constant deficit irrigation strategy for the two proposed sowing dates under the climatic conditions of 2012. In economic terms, the gross margin reached 6849 and 5881€ha−1 for the first and second sowing dates, respectively.

Combination of typical meteorological year with regulated deficit irrigation to improve the profitability of garlic growing in central spain

This paper shows an adaptation of the typical meteorological year (TMY) method for irrigation schedule forecasting in combination with the optimized regulated deficit irrigation (ORDI) strategy to increase the water productivity of crops and their profitability. This methodology has been simulated using the MOPECO model on garlic (Mulvico cultivar) under deficit irrigation conditions in Castilla-La Mancha (Spain), although it may be useful for other crops and areas in the world. Experimental data from a three-year field test were collected for the calibration (2001) and validation (2000 and 2002) processes. Key objectives of this research were: (1) to adapt the TMY methodology for irrigation schedule forecasting; (2) to calibrate and validate the parameters required for simulating garlic using the MOPECO model; and (3) to determine the most suitable irrigation strategy for the Protected Geographical Indication “Ajo morado de Las Pedroñeras” considering four deficit targets (100, 90, 80, and 70% of maximum evapotranspiration) using ORDI and TMY methodologies. The growing-degree-days for the whole growth cycle are approximately 2044°C, while the calibrated crop yield response (Ky) values for the growth stages proposed by FAO-56 are 0.45 (vegetative period), 0.75 (yield formation), and 0.3 (ripening). The combination of TMY with ORDI may increase yield by 3–9% and gross margin by up to 59% compared to a constant deficit irrigation strategy. When water deficit conditions are present, it is of interest to guarantee nascence but also favour the bulb formation stages as much as possible, inducing water stress during the vegetative development stage. Under the current harvest sale price scenario (1.15€kg−1), this crop reaches a gross margin of around 3400€ha−1 for maximum yield (11,200kgha). Thus, irrigation advisory services can supply important information to farmers that may be translated to higher profitability and crop yield at the farm and/or basin scale.

Simulation of onion crop behavior under optimized regulated deficit irrigation using MOPECO model in a semi-arid environment

This paper describes the calibration (year 2005) and validation (year 2003) processes for the simulation of an onion crop (Himalaya cultivar) in a two-year field test under deficit irrigation conditions in Castilla-La Mancha (Spain) using the MOPECO model. Results show that MOPECO is suitable for simulating the yield versus total water use under the climatic and soil conditions in this study (RMSE=7462kgha−1, and relative error=10.1%, between observed and simulated yields). Growing-degree-days (GDD) for the whole growth cycle is around 2283.4°C, while the crop coefficient (Kc: 0.65, 1.20, and 0.75) and calibrated crop yield response (Ky: 0.45, 0.8, and 0.2) values for the growth stages proposed by FAO are similar to those presented in the literature. The electrical conductivity of the irrigation water in the area (0.85dSm−1) can be neglected when simulating the yield response of onion to water (over-estimations up to 7% without considering the effect of salinity). Under the current harvest sale price scenarios (0.12€kg−1 if onions are sold after harvest and up to 0.20€kg−1 if onions are stored to sell at a higher price later), this crop is one of the most profitable in the area, reaching a gross margin between 1750 and 2620€ha−1, respectively, for an average yield (70,000kgha−1). Even though optimized regulated deficit irrigation (ORDI) may slightly increase yield by 3–7%, the gross margin may significantly raise up to 30% compared with an irrigation strategy where the stress levels remain constant during the whole growth cycle. Hence, for medium and high water deficit conditions it is of interest to guarantee nascence and to favor the bulb formation stage as much as possible. For low and medium-low water deficit scenarios, nascence and establishment are guaranteed, and the model assigns more water to vegetative development than to ripening.

Determination of optimal regulated deficit irrigation strategies for maize in a semi-arid environment

For a certain overall deficit target, this paper develops a methodology (Optimized Regulated Deficit Irrigation (ORDI)) for determining the stress level (in terms of the rate between actual crop evapotranspiration (ETa) and maximum evapotranspiration (ETm)) that can be applied to each growth period for maximum yield. ORDI is based on the equation proposed by Stewart et al. (1977) and compatible with the MOPECO model. Once the equation is calibrated and validated, ORDI just requires adjusting the determining factors for optimization.Parameters required for the simulation of maize through the equation proposed by Stewart et al. (1977) were calibrated and validated using the experimental data from a three-year maize field trial (2001, 2002 and 2003) under deficit irrigation conditions in Castilla-La Mancha (Spain). The area is classified as semi-arid and the stress levels applied to the crop ranged between 0 and 60% of ETm. The same data were used to validate the use of ORDI in a maize crop through adjusting the determining factors for optimization. Climatic data from the years 2001–2008 were used for calculating the theoretical average distribution of stress, by growth stage, that leads to maximum yield for four overall stress levels (0.6, 0.7, 0.8, and 0.9). These results were inserted in MOPECO to simulate the behavior of a maize crop subjected to different deficit irrigation strategies under the climatic conditions of the years 2009–2011.Depending on the applied stress level and the restrictions imposed to the optimizer, ORDI may increase yield by 10–20% and gross margin up to 167€ha−1 compared with an irrigation strategy where the stress level remains constant during the whole growth cycle. Hence, for low water stress conditions, deficit irrigation should be applied during the initial and vegetative development stages. For medium and high water stress conditions, higher deficit should occur during the ripening and grain filling stages. Lastly, this methodology can be applied to schedule the levels of water stress to be applied in future experiments on deficit irrigation with herbaceous crops such as maize.

Simulation of maize crop behavior under deficit irrigation using MOPECO model in a semi-arid environment

Through the experimental data of a three year maize field test, this paper shows the calibration (year 2003) and validation (years 2001 and 2002) processes for the simulation of FAO-700 maize crop (Dracma and Brasco hybrids) under deficit irrigation conditions in Castilla-La Mancha (Spain) using the MOPECO model. Key objectives of this research were: (1) determining the length of growth stages using the growing-degree-days (GDD) method; (2) an analysis of the effect of saline irrigation water on crop yield; and (3) a sensitivity analysis of the main factors affecting gross margin (i.e. irrigation water cost, harvest sale price, and uniformity of irrigation). Results show that MOPECO is suitable for simulating the yield versus total water (gross irrigation+effective rainfall) relationships under the climatic and soil conditions in this study (RMSE=1199kgha−1, relative error=7.7%, and similarity rate=0.94, between observed and simulated yields). GDD for the whole growth cycle is around 1802.8°C, while calibrated crop coefficient (Kc) and crop yield response (ky) values for the four growth stages proposed by FAO-56 are similar to those presented in the literature, which provides evidence that this methodology is appropriate for simulating the behavior of herbaceous crops such as maize under different scenarios of water supply. The electrical conductivity of the irrigation water in the area (0.85dSm−1) does not significantly affect the final yield of this crop (up to 4.7% higher without considering the effect of salinity) for the irrigation amount commonly applied in the area (around 650mm). Under the current harvest sale price scenario (0.15€kg−1), costs have greatly decreased the profitability of maize in the area, reaching 400€ha−1. Changing the management of the crop for deficit irrigation strategies may save water that can be used by other crops, thereby obtaining a higher gross margin on farms.

MOPECO: an economic optimization model for irrigation water management

Water is a natural, sometimes scarce, and fundamental resource for life, essential both for agriculture in many regions of the world and also to achieve sustainability in production systems. Maximizing net returns with the available resources is of the utmost importance, but doing so is a complex problem, owing to the many factors that affect this process (e.g. climatic variability, irrigation system configuration, production costs, subsidy policies). The MOPECO model is a tool for identifying optimal production plans, and water irrigation management strategies. The model estimates crop yield, production and gross margin as a function of the irrigation depth. Finally, these gross margin functions are used to determine an optimum cropping pattern and irrigation strategy to maximize the gross margin on a farm in a specific scenario. Since the relationships between the variables are generally non-linear and the number of alternative strategies is quite large, the optimum process is complex and computationally intensive. Genetic algorithms are therefore used to identify optimal strategies. This paper describes the MOPECO model, which comprises three computing modules: (1) estimation of net water requirements; (2) derivation of the relationship between gross margin and irrigation depth; and (3) identification of the crop planning and the water volumes to be applied. The results obtained by applying the MOPECO model to a specific irrigable area in a semi-arid area of Spain, with great deficits and high water costs, are also included and discussed. These results usually show that the irrigation depth for maximum benefits is lower than that necessary to obtain maximum production. In some areas of Spain, horticultural crops are nearly always part of the optimum alternative. The crops that become part of the optimum alternative are mainly horticultural crops with a high gross margin and low water requirements. The irrigation depths selected for the ideal crop rotation are included among the irrigation depth of maximum economic efficiency and the maximum gross margin irrigation depth. Both are lower than that necessary for the maximum yield. This model helps farmers, extension services, and other agents to analyse, make decisions and optimize water management.

04/00564 XAFS and Mössbauer spectroscopy characterization of supported binary catalysts for nonoxidative dehydrogenation of methane: Shah, S. et al. Fuel Processing Technology, 2003, 83, (1–3), 163–173.

The aim of MOPECO model is to maximize the gross margin of irrigated farms by a more efficient use of both the irrigable land and the irrigation water. One limitation of this model is its inability to simulate the effect of deficit irrigation on the quality of the harvests, which may affect the price perceived by the farmers. During the experiment, a farm located in Albacete (Spain) was managed by two different strategies during years 2014 and 2015. In the first strategy, the distribution of crops composed of barley, maize and onion was managed applying full irrigation (F). In the second strategy, crops were irrigated applying full irrigation or the optimized regulated deficit irrigation (O) methodology developed for MOPECO, depending on the available volume of irrigation water. The deficit levels determined by the model for reaching the maximum profitability were 0.7 of maximum evapotranspiration (ETm) for barley, and 0.9 ETm for maize and onion. The aim was to analyze the effect of the O methodology on the water productivity of the crops, on the quality of the harvests, and to determine if the O treatments would be economically penalized with regards to the F treatments due to quality drops. Hence, the O treatments reached a higher water productivity in terms of total dry biomass (average increase: 0.68 kg m−3 for barley, 0.15 kg m−3 for maize, and 0.01 kg m−3 for onion) and dry yield (average increase: 0.26 kg m−3 for barley, 0.08 kg m−3 for maize, and 0.03 kg m−3 for onion). The quality of the harvests and the significant differences found in this study (weight of barley and maize grains, and calibres size of bulbs in onion) did not affect the price perceived by the farmer. Due to this, the O strategy reached a higher profitability than F in the scenarios with lower availability of irrigation water (≤5000 m3 ha−1) (Part I). Therefore, the use of MOPECO at great scale may increase the profitability of farms located in water scarcity areas through a more efficient use of land and irrigation water.