Characterization of water requirements in Extremadura (Spain) for processing tomato

The processing tomato crop is the main food crop in Extremadura, with an irrigated surface area of 21, 674 ha in the 2014 season, and a yield of over 1.4 million tons (74.92% of Spanish national production). The primary growing areas are in Las Vegas along the Guadiana River, stretching some 150 km from the regions of La Serena and La Siberia to the capital of Badajoz, where the river forms a natural border with Portugal. It is an extremely important agricultural area that has been transformed from a dryland farming zone by means of a national irrigation program. Water is a defining factor for the world economy due to its dwindling availability and declining quality, combined with the challenge in ensuring its secure and consistent distribution. Rainfall estimates and water distribution programs remain uncertain, particularly in the world's driest areas, but an intergovernmental panel of experts on climate change warn that the areas that will be the hardest hit by climate stress will be semi-arid areas such as Spain. The classification of growing areas, according to water requirements, based on different crop cycles, allows us to predict requirements and adapt our choice of plant varieties. Zoning studies not only serve to determine the production potential, but also to analyse variability and provide the basis for sustainable management. Data from weather stations belonging to the Irrigation observation network of the regional council estimate water needs for growing different tomato varieties for short-, medium- and long-term cycles as 110, 140 and 160 days, respectively. From these data, a principal components analysis (PCA) was performed to limit discrepancies among the variables studied. Furthermore, to obtain a climate grouping based on specific criteria, a ranking system was introduced. Once the number of clusters was defined, a non-hierarchical classification was performed to group stations into subgroups. The results highlight the variety of differing irrigation needs that exist in cultivated areas and identify homogeneity in the area in general.