Mineral‑fungal interactions in response to biochar amendment: implications for carbon storage in saline-alkali soil

Abstract

Background

Biochar application has been widely acknowledged as an environment-friendly practice to promote soil organic carbon (SOC) stabilization and sequestration in agroecosystems. However, the interaction between fungal and minerals on organic carbon storage and stabilization with biochar application still remains unclear in saline-alkaline soil.

Methods

In the present research, this interaction has been studied by following 6 years treatments at an experimental farm: i) CK, without any fertilization; ii) NPK, only mineral fertilizer; iii) BC, 8.0 Mg ha⁻¹ biochar-based NPK and iv) FeBC, 8.0 Mg ha⁻¹ Fe modified biochar-based NPK, respectively.

Results

The results show that the relative content of illite in BC and FeBC treatments was 4.8%-5.1% higher than that in NPK treatment. Moreover, more stable OC fractions and functional groups, including particulate organic carbon (POC) and aromatic-C, were found in BC and FeBC treatments. Meanwhile, a positive relationship between illite and aromatic-C was found. The two of which might form organic-mineral complexes to decrease specific C mineralization rate. Besides, biochar application increased the diversity of soil fungal community and composition at the phylum level, such as Ascomycota. Redundancy analysis revealed that the content of soil POC and SOC was the major property affecting fungal diversity. Furthermore, the relative abundance of Ascomycota and Basidiomycota was positively correlated with SOC storage.

Conclusion

Effects of biochar, especially Fe-modified biochar last up to six years to improve the stability and storage of SOC in saline-alkali paddy soils, which may be a better agro-management practice.