Biochar affects the structure rather than the total biomass of microbial communities in temperate soils

Franziska Rempt,Franz Zehetner,Andrea Watzinger,Barbara Kitzler,Sophie Zechmeister-Boltenstern,Elena Anders,Gerhard Soja,Bernhard Wimmer,Karl Stahr

doi:10.23986/afsci.8095

Abstract

Biochar application is a promising strategy for sequestering carbon in agricultural soils and for improving degraded soils. Nonetheless, contradictory and unsettled issues remain. This study investigates whether biochar influences the soil microbial biomass and community structure using phospholipid fatty acid (PLFA) analysis. We monitored the effects of four different types of biochar on the soil microbial communities in three temperate soils of Austria over several months. A greenhouse experiment and two field experiments were conducted. The biochar application did not significantly increase or decrease the microbial biomass. Only the addition of vineyard pruning biochar pyrolysed at 400°C caused microbial biomass to increase in the greenhouse experiment. The biochar treatments however caused shifts in microbial communities (visualized by principal component analysis). We concluded that the shifts in the microbial community structure are an indirect rather than a direct effect and depend on soil conditions and nutrient status.

Highlights

Biochar is the solid residue obtained after the pyrolysis of organic material under the exclusion of oxygen
The treatment E_VN400 even showed an increase until day 170, whereas in the other treatments the phospholipid fatty acid (PLFA) sum slowly declined from day 86
The PLFA sums of treatments with biochar were slightly lower compared to the controls

Summary

Introduction

Biochar is the solid residue obtained after the pyrolysis of organic material under the exclusion of oxygen. Biochar as a soil amendment has become an important topic in soil science in the past few years, and many research groups are studying the effects of biochar on (agro) ecosystems. The investigations tackle issues such as carbon sequestration, reduction of greenhouse gas emissions, regeneration of degraded soils, biochar as a possible nutrient carrier for better plant growth and enhancement of microbial proliferation. Terra preta is the oldest documented form of biochar amendment in soils. In these Anthrosols in the Amazon region, biochar was found to enhance microbial growth compared to the same soil without biochar (Grossman et al 2010). In temperate Australian soils, biochar (650−1600 years old) improved soil fertility (Downie et al 2011)

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