Abstract
Biochar has received much attention as a strategy to enhance soil carbon (C) sequestration and mitigate climate change. Previous studies found that the feedstock and pyrolysis temperature can largely determine biochar properties, which in turn, impact the stability of native soil organic matter (SOM) and soil microorganisms. The Schima superba and Cunninghamia lanceolata are two tree species widely distributed in the subtropical region of southern China, but how the biochars from these two species influence the soil C sequestration and microbial communities of plantation remain poorly understood. In this study, we produced biochars from these two different feedstocks (13C-labeled S. superba and C. lanceolata litters) at three pyrolysis temperatures (350°C, 550°C, 750°C), then added them to the soils from C. lanceolata plantation, and maintained the experiments at 25°C for 112 days. We found both C mineralization and soil microbial community structures were strongly, but inconsistent, affected by biochar feedstock and pyrolysis temperature. The C. lanceolata biochar triggered the negative priming effect faster and greater compared with the S. superba biochar amendment. Biochars produced at 550°C showed the most significant negative priming effect during the whole incubation period, regardless of the different feedstocks. The cumulative amount of CO2 derived from biochars was significantly decreased with pyrolysis temperature (p < 0.05), indicating that biochars prepared at higher temperatures were more stable in the soil. Further, the soil microbial community structure was only affected by biochar pyrolysis temperature rather than biochar feedstock and their interaction. Together, our results reveal that biochar feedstock and pyrolysis temperature may play more important roles in dictating the priming effect than the structure of microbial community for C. lanceolata plantation. Overall, we concluded that the biochars prepared at 550°C could rapidly decrease the turnover of native SOM in a short term and biochar amendment has the potential to be a management practice for soil C sequestration in the C. lanceolata plantation.
Highlights
Forest plantations in China account for about one-third of the global area of plantation and contributed about 80% of the total forest C sink increment in China (Fang et al, 2014; Li et al, 2018)
The cumulative amounts of CO2 derived from biochar and native Soil organic matter (SOM) were significantly affected by biochar feedstock, pyrolysis temperature, and their interaction (Figure 1, Supplementary Table S1)
The cumulative amount of CO2 from biochar was significantly greater in the S. superbaderived biochar treatment than in the C. lanceolata-derived biochar treatment, while it was significantly decreased with the pyrolysis temperature in the two feedstock treatments (p < 0.05)
Summary
Forest plantations in China account for about one-third of the global area of plantation and contributed about 80% of the total forest C sink increment in China (Fang et al, 2014; Li et al, 2018) Management practices such as fertilization and harvest residue may notably alter soil C storage and affect the C sequestration of forest plantations (Vogel et al, 2015; Wan et al, 2018). Biochar is a carbon-rich product produced by plant or animal residues at high temperatures pyrolysis under limited or no supply of oxygen (Woolf et al, 2010; Hansen et al, 2016) It has received much attention as an effective soil amendment due to its beneficial properties for improving soil fertility and mitigating climate change in recent years (Fowles, 2007; Gomez et al, 2014; Fatima et al, 2021). The potential of biochar for soil C stability and sequestration is extremely essential and enormous (Yuan et al, 2019), and the influence of biochar on C sequestration must be better understood
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