Carbon Fixation and Soil Aggregation Affected by Biochar Oxidized with Hydrogen Peroxide: Considering the Efficiency of Pyrolysis Temperature.

Ghorbani, Mohammad; Neugschwandtner, Reinhard W.; Soja, Gerhard; Konvalina, Petr; Kopecký, Marek

Biochar, as a carbon-rich material, may have a notable influence on carbon balance, especially that in soil mediums. The oxidation of biochar modifies the biochar's effects on the soil's carbon dynamics. To evaluate the alteration in soil carbon storage, biochars derived from wheat straw (WS) and wood residues (WR) produced at 350, 450, and 550 °C (marked BWS350, BWS450, BWS550, BWR350, BWR450, and BWR550) were oxidized with hydrogen peroxide (H2O2) and applied on a loamy soil (2% d.m.) for a 180-day greenhouse incubation period. The highest organic carbon (OC) concentration and carbon pool index (CPI) were obtained from the oxidized BWS550, with 154% and 70% increases, respectively, compared to the unamended control. For both the WS and WR biochars, applying oxidation significantly improved the soil's aggregation indices, i.e., the mean weight diameter (MWD), water stable aggregates (WSA), and fractal dimension (D). BWS350, BWS450, and BWS550 showed significantly higher WSAs, with percentages of 68, 74, and 76% compared to the control (41%). The fractal dimensions decreased with an increasing pyrolysis temperature in both the biochar types. All the biochar treatments significantly decreased the soil bulk density (BD), while for both the pristine and oxidized biochars, the lowest BD was related to the biochars produced at high temperatures. The structural qualities of the biochars were enhanced by oxidation, particularly their specific surface areas and porosities, and this had a substantial impact on the soil structure and carbon status. The wheat straw biochar was more effective than the wood residue biochar and a higher pyrolysis temperature was more effective than lower ones for supporting the enhancement of the soil carbon pool.

CARBON in soils; CARBON fixation; BIOCHAR; HYDROGEN peroxide; WOOD waste; SANDY soils; SOIL testing

Sustainability (2071-1050), 2023, Vol 15, Issue 9, p7158

2071-1050

Academic Journal

10.3390/su15097158