| Authors |
Diacono, M; Gebremikael, MT; Testani, E; Persiani, A; Fiore, A; Alfano, V; Ciaccia, C; Montemurro, F; De Neve, S |
| Abstract |
Agricultural Wastes, Co-products, and By-products (AWCB) can be recycled to produce profitable added-value products, such as organic fertilizers. Newly produced AWCB-based fertilizers were thus tested both under laboratory and field conditions in a two-year organic zucchini-lettuce rotation. In a split plot experimental design, the main-plot factor being the green manure (GM) presence or absence, the following fertilizing treatments were compared: (i) co-composted cattle manure anaerobic digestate; (ii) re-composted olive waste compost; (iii) a commercial dried manure organic fertilizer, and iv) a municipal solid waste compost. The aims were to assess: the potential C and N mineralization, changes on soil microbial and chemical properties and the crop yields. Moreover, the residual effect of the fertilization applied before zucchini transplanting on lettuce yield was evaluated. The composts and the commercial organic fertilizer did not significantly change the soil microbial and chemical properties, and crops yield. The GM was the most effective treatment, as highlighted by the highest microbial biomass carbon and dehydrogenase activity, the highest C and N input and the increase of soil TOC. Weather conditions may have contributed to a 55% higher zucchini yield in the second cropping cycle, despite the lowest soil mineral N in GM, and reduced the lettuce yield by 59%. The residual effect of the fertilization applied before zucchini did not affect the subsequent lettuce yield in the first year. In conclusion, AWCB-based fertilization can enhance the soil biochemical dynamics in organic vegetable systems, particularly combined with other agroecological practices, such as GM. Agricultural Wastes, Co-products, and By-products (AWCB), generated in huge amounts along the agrifood systems, should be recycled to meet the circular economy principles, thus producing profitable added-value products in agriculture, such as organic fertilizers. Although the possible utilization of many AWCB in agriculture was already evaluated by many authors, there is a need of further knowledge on the main effects on the soil of newly produced AWCB-based fertilizers under Mediterranean conditions. This is also linked to the unpredictable behaviour of AWBC due to a wide variability in physicochemical and biological properties, depending on the treatment process and raw materials used. The lack of knowledge may lead to improper application to soil, resulting in low agronomic efficiency and environmental pollution. To allow efficient and environmentally sound waste recycling, laboratory or pot experiments were set up in other studies not combining both types of experimentation. By contrast, we combined laboratory incubation with field experiments in organic crop rotations, testing newly produced AWCB-based fertilizers directly related to farm reality and site-specific context. Fertilizers can be produced also on-farm by recycling agricultural wastes.Combined incubation experiments and field trials on AWCB fertilizers were performed.AWCB and GM are effective agroecological practices in Mediterranean area. |