B. HERRERO1, M. E. BLÁZQUEZ1 and M. D. CRISTÓBAL2
1 Departamento de Ciencias Agroforestales, Universidad de Valladolid, 34004 Palencia, Spain
2 Departamento de Producción Vegetal y Reurcros Forstales, Universidad de Valladolid, 34004 Palencia, Spain
HERRERO, B., M. E. BLÁZQUEZ and M. D. CRISTÓBAL, 2015. Nutrient levels in a productive cycle of hydroponic tomato crop. Bulg. J. Agric. Sci., 21: 160–166
Analysis of nutrient solution (NS) recycling and non-recycling treatments in a hydroponic tomato crop was studied. The aims of the study were to measure nutrient concentration variations along the productive cycle in both treatments, to clarify the differences regarding fruit yield and to assess recycling system viability. Emitter and drained nutrient solution samples from both treatments were analyzed once per week, tomato samples were collected three times per week and they were measured and weighed. The average nitrate concentration in the inlet of the recycling treatment was 11.60 meq/l. The concentration increased by 7.01% in the leachate solution. The average sulfate concentration was 8.07 meq/l in the recycling system supplied solution, and 146.47% higher in leachates. The calcium ion concentration in the recycling system inlet was 9.48 meq/l. The concentration increased by 21.26% in the drained solution. Three analyzed nutrients, i.e. phosphates, potassium and ammonium, presented a lower concentration in the drained solution than in the supplied solution. Average yield per plant was 7.17 kg/plant. Fruit yield was not increased by the recycling technique in the hydroponic crop. No significant differences were found regarding fruit yield, except for the commercialized smallest size tomatoes (57-67 mm diameter), whose production was 226% higher in the non-recycling area. Recycling treatment viability has to be measured in terms of water and fertilizer savings and minimization of polluting waste in drainage solutions.