The management of water and nutrient ions, such as nitrate, has been studied extensively in recent decades. Increasingly efficient models have been developed for the use of water and nutrients through the automation of fertigation techniques. The application of a fertigation volume for a duration four times longer than applied on the control was evaluated. In Almería (Spain), one pepper crop and two tomato crops—with and without grafting—were grown between Oct. 2013 and June 2014 in a soilless system with a coir substrate. The effects on root growth, plant growth, production, and quality were measured. The following parameters for the fertigation of the nutrient solution and drainage were recorded: % drainage volume, electrical conductivity (EC) of the nutrient solution, pH, and concentration of nitrates and potassium. The absorption of potassium and nitrate, and the nitrate emissions of the drainage were estimated. The results showed an increase in the root volume and an improved distribution in the cultivation unit for the treatment application in the pepper crop. Slowing the applied fertigation improved the absorption of water and nitrates, and the production in the ungrafted tomato and pepper crops, while the grafted tomato crop was unaffected. Nitrate emissions were lower in the evaluated treatment of the pepper and ungrafted tomato crops. The fruit quality parameters were unaffected.
Miguel Urrestarazu, Isidro Morales, Tommaso La Malfa, Ruben Checa, Anderson F. Wamser and Juan E. Álvaro
Judith Pozo, Juan E. Álvaro, Isidro Morales, Josefa Requena, Tommaso La Malfa, Pilar C. Mazuela and Miguel Urrestarazu
Volcanic rock has been used for decades as a horticultural substrate worldwide. In Spain, the use of this material as a substrate is ancient; it was initially used in the Canary Islands because of its volcanic geological origin. At the University of Almería (Almería, Spain), three independent vegetable crops were grown under greenhouse conditions: sweet pepper, tomato, and melon. The volcanic rock came from a location in the geographic center of Spain, which facilitated logistics. Bags of volcanic rock (25 L) were used and were compared with a commercial coconut fiber substrate of an equal volume. All physical, physical–chemical, and chemical parameters of the volcanic rock were determined using European standard analytical procedures. Fertigation was applied, independently adapted to the physical, physical–chemical, and chemical characteristics of each substrate. The cultures were performed under a randomized complete block experimental design. Fertigation parameters, pollutant emissions, fruit production, and the quality of each culture were measured. The results showed that the assessed parameters of the volcanic rock substrate are not a limiting factor for its use as a horticultural substrate. The resultant production and quality were very similar among the three crops compared with a widely used commercial control. Therefore, volcanic rock emerges as a local, sustainable alternative to be used for soilless crop cultivation.