During the last 7 years, within the framework of projects Riego-Asesor, Phertilizer and “Fertirriego de precisión para un manejo sostenible de la horticultura intensiva. Aspectos agronómicos e implicaciones ambientales” we have conducted multiple open field trials in the Campo de Cartagena and multiple greenhouse experiments in Santomera (Murcia), either in pot or hydroponic. The trials with vegetable crops include endive, baby lettuce, romaine lettuce, summer wonder lettuce, Iceberg lettuce, piel de sapo melon, and potato. The overall objective of all these projects was to make a more efficient use of two mayor resources used in agriculture; water and nutrients, with special focus on nitrogen. Here we resume the most notable results of these experiments; i) the amount of irrigation water applied by farmers was tightly adjusted and this amount closely mimics the FAO recommendations and custom-made water balance model named “Riego-Asesor”, ii) a fertigation strategy aimed to match water and fertilizer inputs with plant demand is key in improving water and nitrogen use efficiency, and simple to use decision support system was designed for this goal iii) irrigation frequency/dose plays a critical role in improving water and nitrogen use efficiency, with high frequency of irrigation resulting in higher yield and lower nitrate leaching iv) knowing how the nitrogen source (nitrate/ammonium) affects growth and development in different vegetable crops can be a further step of adjustment to increase nitrogen use efficiency. All this information can be used to designing fertigation strategies in intensive agriculture that match and integrate water and nutrients supplies with the needs of a given crop under a given growing conditions.

The authors are grateful to the proyects; Retos Colaboración RTC-2015-3453-2: Riego-Asesor “Asesor virtual para la ayuda a la toma de decisiones sobre estrategias de riego sostenibles”, Retos Colaboración RTC-2017-6049-2: Phertilizer “Sistema circular para la recuperación y valoración agronómica del fósforo”, and project Nº20659/JLI/18 of Comunidad Autónoma de la Región de Murcia (CARM) “Fertirriego de precisión para un manejo sostenible de la horticultura intensiva. Aspectos agronómicos e implicaciones ambientales”.

Trabajo presentado en el XXI International N workshop, celebrado en Madrid (España) del 24 al 28 de Octubre de 2022.