ISHS Acta Horticulturae 807: International Symposium on Strategies Towards Sustainability of Protected Cultivation in Mild Winter Climate
NUTRIENT SOLUTION CONCENTRATIONS IN SOILLESS CLOSED SYSTEM |
| Authors: | F. Giuffrida, C. Leonardi |
| Keywords: | efficiency, electrical conductivity, environment, nutrition, recirculation, tomato |
| Abstract:
In order to overcome the environmental and economical problems that an open soilless cultivation system involves, it is advisable to adopt the recirculation of nutrient solution. Experiments carried out on tomato grown in soilless closed systems showed an accumulation of the ions less used by the crop as well as of the main macronutrients in the recirculating solution especially in high VPD conditions. That promotes the increase of electrical conductivity and thus the necessity of nutrient solution renewal, with a high release of nutrients into the environment. The aim of this research was to extend the recirculation of nutrient solution by reducing the macronutrient concentrations. Tomato plants were grown in perlite using a closed system with two nutrient solutions characterised by the same ion ratios, but different nutrient concentrations equal to 100 or 60%. The total substitution of nutrient solutions was carried out when the EC of recirculating nutrient solutions increased of 2 dS m-1 compared with the initial EC. The lower nutrient concentration resulted in a significant reduction in epigeal dry biomass whereas the yield was not different. Moreover it provided a notable improvement of agronomical water and nitrogen use efficiency. The environmental impact related to the release of exhausted NS was strongly reduced. The amounts of nitrogen, phosphorus and potassium released per ton of tomatoes were 81, 72 and 79% lower than the control, respectively. The recirculation of reduced strength nutrient solution gave rise to depletion of nitrate and ammonium and accumulation of the ions less used by the plants compared to the use of full strength solution. | |
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