A THREE-YEAR FIELD ANAEROBIC DIGESTATES APPLICATION: EFFECTS ON FODDER CROPS PERFORMANCE AND SOIL PROPERTIES

摘要

The objective of this three-year field study was to evaluate, on alfalfa and cocksfoot crops, the agronomic performances of processed industrial wastes in comparison with mineral fertilizers. Their application effects on soil properties were further investigated. Two anaerobic digestates, obtained by the wastewater treatment of wine production process (WWW) and by waste-water from frozen food processing (WFF), were compared with a mineral (MIN) and an unfertilized control (CONTR) in a randomized-block experimental design with three replications. Along the cropping cycles, crops cumulative yield (fresh and dry weight) was determined. Moreover, at the beginning and at the end of the experimental trial soil was analyzed to determine the main chemical properties. In alfalfa, no significant difference was found for cumulative dry weight among MIN and organic treatments during the last two years of field experiment. Furthermore, the mean yield of anaerobic digestate treatments at the end of each year was higher than the CONTR of 2.8, 35.3 and 67.2%. In cocksfoot the application of both anaerobic digestates significantly increased the yield in the first year in comparison with the CONTR (26.2 and 19.7% for WWW and WFF, respectively). In the second year, only WFF application enhanced cumulative dry matter (36.6%), while in the third year no significant difference was found between the organic treatments and the unfertilized CONTR. In alfalfa, the WWW and WFF repeated application significantly increased, in comparison to the CONTR, the soil total organic carbon. In cocksfoot a significant increase of soil organic carbon was only found for the WWW treatment (26.9% of increase). The results indicated that both the anaerobic digestates evaluated in this study could be used to sustain yield production in alfalfa crop and to improve soil properties, so reducing the potential environmental risks associated with mineral fertilizers use. In cocksfoot, positive effects on cumulative dry matter were found only for repeated application of WFF while only WWW determined a significant change in total soil organic content.