Changes in Soil Properties and Bacterial Community Composition with Biochar Amendment after Six Years

Shuxiu Fan,Hangyu Dong,Jiacheng Zuo

doi:10.3390/agronomy10050746

Abstract

Changes in soil physicochemical properties and bacterial community composition were investigated six years after biochar amendment at 0%, 4%, 8% and 12% (w/w), which were coded as C0, C1, C2 and C3, respectively. Results showed that some soil characteristics were sustainable, as they were still affected by biochar addition after six years. Compared to the control, biochar-treated soils had higher pH, total carbon (TC), C/N, total nitrogen (TN), available phosphorus (AP) and available potassium (AK). Soil pH, C/N and the content of TC, TN and AK all increased along with the increase of biochar dosage. The results of Illumina MiSeq sequencing demonstrated that biochar enhanced soil bacteria diversity and modified the community composition over time. The relative abundance of Nitrospirae and Verrucomicrobia phylum increased but that of Acidobacteria phylum decreased significantly in biochar amended soils. The addition of biochar also enriched some bacterial genera, such as uncultured Nitrosomonadace, uncultured Gemmatimonadac, uncultured Nitrospiraceae and Magnetovibrio. In particular, the relative abundance of uncultured Nitrospiraceae was enhanced by 16.9%, 42.8% and 73.6% in C1, C2 and C3, respectively, compared to C0. Biochar has a potential role in enhancing the abundance of bacteria involved in N cycling. Soil pH, TC, TN, TK and AK, were closely related to alterations in the composition of the soil bacterial community. Meanwhile, these soil properties were significantly influenced by biochar amendment, which indicates that biochar affected the soil microbial community indirectly by altering the soil characteristics in the long term.

Highlights

Biochar is a stable, highly aromatic and carbon-rich substance derived from pyrolysis of different biological residues under limited oxygen conditions [1]
Our study showed that biochar significantly changed the soil properties, while the Redundancy analysis (RDA) results revealed that soil pH, total nitrogen (TN), C/N, total carbon (TC), TK, available nitrogen (AN), AK was closely related to the variations in bacterial communities (Figure 4)
Biochar amendment improved a number of soil physicochemical properties, including pH, TC, TN, TK and AK six years after addition in soils

Summary

Introduction

Highly aromatic and carbon-rich substance derived from pyrolysis of different biological residues under limited oxygen conditions [1]. As biochar helps to improve soil quality and crop productivity, increases carbon storage, decreases greenhouse gas emissions and environmental remediation, more and more research on biochar has been carried out in the past decade [2,3,4,5,6,7]. Biochar reduced wheat and radish biomass [17], and decreased mineral nitrogen availability in soils [5]. The effectiveness of biochar application varies with soil type, crop species, the biomass feedstock and pyrolysis conditions, which highlights the need for further investigation on biochar’s effect when applied to soil

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Discussion

Conclusion