Anaerobic digestion is a technique of growing interest as a promising option for waste disposal and green energy production. The anaerobic effluents (digestate) are a mixture of water (about 95 %) and partially degraded organic matter. Afterwards separation of the two components (liquid and solid), the inorganic ions with a fertilizer value are concentrated mainly in the liquid one. The main limitation to their agricultural use could be the sodium chloride content derived from the initial matrices and the potential phytotoxicity originated from partially decomposed organic matter. In this study the main agrochemical characteristics and the phytotoxicity of eight digestates (derived from co-digestion of posidonia residues with different pretreatments - grinding, washing and autoclave treatments - and a mixture of urban sludges and organic wastes) were evaluated in order to assess their potential use as a source of water and nutrient elements in vegetable seedling production. Lettuce (Lactuca sativa L. var. Ezra) seedlings for transplant were produced on peat based substrate. Digestates liquid fraction (LD), obtained after centrifugation, was used to integrate the nutrient solution at rate of 1:10 v/v; a standard nutrient solution for lettuce seedling cultivation was used as a control (NS). Main chemical properties (pH, EC, inorganic ions content) of LD, shoot and root fresh and dry weight, leaf area, root morphology, root/shoot ratio were determined. Different content of Cl- and Na+ were found in LD in relation to the posidonia residues pre-treatment; moreover LD contained in general high concentration of NH4+, K2+, Mg2+ and Ca2+. Plants cultivated using LD showed a root/shoot ratio (important to ensure good engraftment after transplanting) not significally different from plants grown with NS. The use of LD produced a fresh water saving of 10% and the reduction of mineral fertilizers use. The liquid fraction of digestates could be a good source of macro nutrients and water, and first results indicate that could be re-utilized in relation to its salts content as nutrient solution for lettuce seedling production and likely in soilless cultivation systems.
EVALUATION OF ANAEROBIC DIGESTATES LIQUID FRACTION FROM POSIDONIA RESIDUES AS NUTRIENT SOLUTION FOR LETTUCE SEEDLING PRODUCTION
Carlo Mininni;Francesco Serio;Angelo Parente
2015
Abstract
Anaerobic digestion is a technique of growing interest as a promising option for waste disposal and green energy production. The anaerobic effluents (digestate) are a mixture of water (about 95 %) and partially degraded organic matter. Afterwards separation of the two components (liquid and solid), the inorganic ions with a fertilizer value are concentrated mainly in the liquid one. The main limitation to their agricultural use could be the sodium chloride content derived from the initial matrices and the potential phytotoxicity originated from partially decomposed organic matter. In this study the main agrochemical characteristics and the phytotoxicity of eight digestates (derived from co-digestion of posidonia residues with different pretreatments - grinding, washing and autoclave treatments - and a mixture of urban sludges and organic wastes) were evaluated in order to assess their potential use as a source of water and nutrient elements in vegetable seedling production. Lettuce (Lactuca sativa L. var. Ezra) seedlings for transplant were produced on peat based substrate. Digestates liquid fraction (LD), obtained after centrifugation, was used to integrate the nutrient solution at rate of 1:10 v/v; a standard nutrient solution for lettuce seedling cultivation was used as a control (NS). Main chemical properties (pH, EC, inorganic ions content) of LD, shoot and root fresh and dry weight, leaf area, root morphology, root/shoot ratio were determined. Different content of Cl- and Na+ were found in LD in relation to the posidonia residues pre-treatment; moreover LD contained in general high concentration of NH4+, K2+, Mg2+ and Ca2+. Plants cultivated using LD showed a root/shoot ratio (important to ensure good engraftment after transplanting) not significally different from plants grown with NS. The use of LD produced a fresh water saving of 10% and the reduction of mineral fertilizers use. The liquid fraction of digestates could be a good source of macro nutrients and water, and first results indicate that could be re-utilized in relation to its salts content as nutrient solution for lettuce seedling production and likely in soilless cultivation systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
