Recycling of wastes from fish beneficiation by composting: chemical characteristics of the compost and efficiency of their humic acids in stimulating the growth of lettuce

• Published in: Environmental science and pollution research international 2018-12, Vol.25 (36), p.35811-35820
• Main Authors: Busato, Jader Galba, de Carvalho, Caroline Moreira, Zandonadi, Daniel Basilio, Sodré, Fernando Fabriz, Mol, Alan Ribeiro, de Oliveira, Aline Lima, Navarro, Rodrigo Diana
• Format: Article
• Language: English
• Subjects: Acidity; Animals; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Beneficiation; Carbon dioxide; Carbon/nitrogen ratio; Composting; Composts; Conductance; Copper; Decomposing organic matter; Earth and Environmental Science; Ecotoxicology; Electrical conductivity; Electrical resistivity; Environment; Environmental Chemistry; Environmental Health; Environmental science; Extrusion; Fertilizers - analysis; Fish; Fishes; Functional groups; Humic acids; Humic Substances - analysis; Humus; Iron; Lactuca - growth & development; Lettuce; Lipids; Manganese; NMR; Nuclear magnetic resonance; Organic fertilizers; Oxidation; pH effects; Phenols; Plant growth; Poaceae - chemistry; Recycling; Residues; Resistance; Soil - chemistry; Solid Waste - analysis; Stimulants; Stomata; Stomatal conductance; Sustainable Waste Management; Waste recycling; Waste Water Technology; Water Management; Water Pollution Control; Water use
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-0795-3

Waste from the beneficiation of fish was composted with crushed grass aiming to characterize their chemical composition and investigate the possibility of the use of the final compost as source of humic acids (HA) able to stimulate the growth of lettuce. Compost presented pH value, C/N ratio, and electrical conductivity that allow its use as an organic fertilizer. The element content was present in the following order of abundance in the compost: P > Ca > N > Mg > K > Fe > Zn > Mn > Mo > Cu, and the humus composition was similar to that observed in others kind of organic residues composted. The high content of oxygen pointed out a high level of oxidation of HA, in line with the predominance of phenolic acidity in the functional groups. The 13 C-NMR spectra showed marked resonances due to the presence of lipids and other materials resistant to degradation as methoxy substituent and N-alkyl groups. A concentration of 20 mg L −1 HA increased significantly both dry and wet root matter in lettuce but the CO 2 assimilation, stomatal conductance, and number of lateral roots of the plants were not affected. However, increases of 64% in the water-use efficiency was observed due to the HA addition, probably related to the root morphology alteration which resulted in 1.6-fold increase of lateral root average length and due to the higher H + extrusion activity. Reuse of residues from the fish beneficiation activity by composting may represent a safe tool to increase the value of recycled organic residues and generate HA with potential use as plant growth stimulants.