Evaluating the potential of hydrochar as a soil amendment. (15th March 2023)

• Record Type: Journal Article
• Authors: Bona, Daniela; Bertoldi, Daniela; Borgonovo, Gigliola; Mazzini, Stefania; Ravasi, Stefano; Silvestri, Silvia; Zaccone, Claudio; Giannetta, Beatrice; Tambone, Fulvia
• Is Part Of: Waste management. Volume 159(2023)
• Page Start: 75
• Page End: 83
• Publication Date: 2023-03-15
• Subjects: 1H NMR -- 13C CPMAS NMR -- Thermal analysis -- Lactuca sativa -- Compost -- Phytotoxicity; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2023.01.024
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Hydrochar composition was investigated in relation to its potential phytotoxicity. Hydrochar shows high content of aliphatic, easily degradable molecules. High doses of hydrochar can cause phenomena of phytotoxicity. Stabilized hydrochar can contribute to the soil organic matter balance. Mix of hydrochar and compost shows high fertilizer performances. Abstract: In this study, hydrochar (HC), a carbon-rich product originated from hydrothermal conversion treatment (HTC), was obtained from wastes of the wine and dairy industries. The effect of mixing secondary char and compost was tested, before and after the aerobic mixing of compost (COM) and HC at increasing doses (from 15 to 75 Mg ha −1 DM), in an effort to lower the HC phytotoxicity due to potential phytotoxic compounds of secondary char. The results indicated that, after the aerobic stabilization, the mix HC/COM was able to double the plant growth in comparison to COM alone. The presence of easily degradable organic compounds probably led to poor stability of HC, increased microbial activity and, consequently, root anoxia when used at high doses. Chemical, spectroscopic and thermal investigation confirmed this hypothesis. In particular, HC shows a high content of dissolved organic matter, characterized by the presence of small molecules, which is negatively correlated with the growth index of lettuce. Furthermore, thermal characterization suggests a higher proportion of less complex and thermally stable molecular compounds in HC in comparison to COM. Therefore, co-composting of HC allows obtaining a useful amendment to support soil organic matter and fertility.