Introducción El crecimiento de la superficie de horticultura intensiva desarro- llada en el litoral Mediterráneo ha derivado en un déficit hídrico en las principales zonas de producción, produciéndose la sobre- explotación de los recursos tradicionales (normalmente aguas subterráneas) y convirtiéndose la disponibilidad de agua en un factor limitante. Las soluciones aplicadas a esta problemática han sido: búsqueda de fuentes alternativas de agua (principalmente desaladas y residuales urbanas regeneradas), mejora de la efi- ciencia en el almacenamiento y transporte del agua y mejora de la FERTILIZACIÓN One of the technological trends to improve the efficiency of water and nutrient use is the use of soil humidity sensors to activate irrigation automatically. The objectives of the work developed from the IFAPA La Mojonera centre in this line are focused on studying the effect of soil matrix potential on bio- productivity, water use efficiency, defined as the production obtained per volume of water used (USA) and the efficiency of nutrient use, defined as the production obtained per amount of nutrient applied in fertigation. Several experiments have been developed in zucchini and pepper crops. The tests have been carried out in a 'parral' type greenhouse with sandy soil and fertigation. The results show that the system of automatic activation of fertigation with electrotensiometers for soil crops has been shown to be effective in maintaining soil moisture. The consumption of water and fertilizers has varied depending on the humidity level established, potentials closer to zero increase the volume of fertigation applied and produce an increase in commercial production, both in zucchini and pepper. In zucchini, combining production and environmental criteria, the T2 treatment (-20kPa) is the one with the best performance, with a very high efficiency in the use of water and nutrients and a fruit production of 15 kg m-2. The characteristics of the cultivar can influence the consumption and efficiency in the use of water and nutrients by the crop. 43