Carbon fractionation and sequestration in soil amended with fruit waste-derived biochar

Abstract

The most crucial and recent environmental concern is global warming, which is increasing at an alarming rate. Among the greenhouse gases emissions, CO2 is of keen concern which contributes significantly to climate change. The concentrations of CO2 and other greenhouse gases in the atmosphere need to be stabilized. This study was carried out to attempt reductions in CO2 emissions from soil into the atmosphere with the help of fruit waste-derived biochar and fertilizer treatments. Orange peel biomass was pyrolyzed at different temperatures (300, 500, and 700°C) to produce biochars, which were applied to alkaline soil to assess CO2-C efflux, C-sequestration, and C-fractions. Cumulative CO2-C efflux and soil quality were measured throughout the course of 156-day incubation experiment. The results showed that biochars produced at 300°C was more effective in increasing cumulative C mineralization from soil (0.075 ± 0.001 g kg-1) due to availability of more organic content to microbial mass, hence their increased activity, resulting in greater CO2 evolutions. However, biochars manufactured at higher temperatures (500°C and 700°C) contained aromatic C contents due to their recalcitrant nature, they demonstrated stronger resistance in soil. This aided in capturing C in soil, resulting in fewer atmospheric CO2 emissions (0.038 ± 0.001 and 0.037 ± 0.001 g kg-1, respectively). Furthermore, the separated particulate and mineral-associated organic carbon fractions recorded at the end of incubation experiment supported these findings, in that the former, being more stable and more responsive to changes in soil, was available in greater quantity than the latter organic matter fraction which showed constant values due to its dependency on microbial activity that decreased with time. Post experiment soil analysis portrayed that these amendments improved the soil quality