Impact of climate change on maize’s water needs, yields and profitability under various water prices in Spain

Abstract

Available water resources are expected to diminish in the Iberian Peninsula as a result of climate change (CC). Agricultural water use represents about 70% of all water uses in Spain. This paper uses a combination of an ensemble of climate change and crop models to analyze the impacts on maize's water needs, yields and economic profitability under various water prices. Maize's evapotranspiration (ET), irrigation needs and yield projections under CC are compared with those of current climate in nine sites of Spain. With these simulated data, maize's and water's prices are included in a stochastic model to simulate the crop's net margin, both under CC and current climate conditions. An adaptation strategy potentially useful for maize in Spain is also studied. Results show that such adaptation can reduce negative CC impact on yields. However, decreases in ET and irrigation needs will be lower with than without adaptation. This creates an ambiguous situation which can be affected or solved with water pricing policies. With higher water tariffs, crop's profitability can drop to negative levels, which may result in the abandoning of the crop in many areas. CC and water policies must be closely coordinated to ensure efficient water use and crops' profitability.Additional key words: adaptation; evapotranspiration; net margin; Regional Climate Models; uncertainty; Zea mays L. ResumenImpacto del cambio climático en el rendimiento y en las necesidades hídricas del maíz, y su rentabilidad bajo diferentes precios del agua en España La disponibilidad de recursos hídricos en la Península Ibérica va a disminuir como consecuencia del cambio climá-tico (CC). En España, el regadío representa cerca del 70% de la demanda total de agua. Este trabajo utiliza un conjunto de modelos climáticos y de cultivo para analizar el impacto en las necesidades hídricas del maíz, en su rendimiento, y en su margen neto bajo diferentes tarifas de agua. Las proyecciones de rendimiento, evapotranspiración (ET) y riego del maíz en el clima futuro han sido comparadas con las del clima actual en nueve zonas de España. También se han evaluado los datos relativos a una posible estrategia de adaptación de este cultivo. Los resultados muestran que esta estrategia puede reducir los impactos negativos del CC en el rendimiento del maíz. Sin embargo, la ET y la necesidad de riego serán mayores con adaptación que sin ella. Esto crea un efecto ambiguo, que puede verse afectado o resolverse con políticas de tarifación del agua. Con mayores niveles de tarifas, debido a una mayor escasez de recursos hídri-cos disponibles consecuencia del CC, la rentabilidad del maíz puede llegar a caer hasta valores negativos, lo que llevaría a su abandono en algunas zonas. Las políticas de CC y de agua deben estar bien coordinadas con el fin de asegurar la eficiencia del uso del agua, y la rentabilidad de los cultivos.Palabras clave adicionales: adaptación; evapotranspiración; incertidumbre; margen neto; Modelos Regionales de Clima; Zea mays L.

Modeling Regional Effects of Climate Change on Soil Organic Carbon in Spain

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Comparison among monitoring strategies to assess water flow dynamic and soil hydraulic properties in agricultural soils

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