Soil Microbial Responses to Biochars Varying in Particle Size, Surface and Pore Properties

Abstract

Biochars are known for their heterogeneity, especially in pore and surface structure associated with pyrolysis processes and sources of feedstocks. The surface area of biochar is likely to be an important determinant of the extent of soil microbial attachment, whereas the porous structure of biochar is expected to provide protection for soil microorganisms. Potential interactions between biochars from different sources and with different particle sizes were investigated in relation to soil microbial properties in a short-term incubation study. Three particle size (sieved) fractions (0.5-1.0, 1.0-2.0 and 2.0-4.0 mm) from three woody biochars produced from jarrah wood, jarrah and wandoo wood and Australian wattle branches, respectively, were incubated in soil at 25 °C for 56 d. Observation by scanning electron microscopy (SEM) and characterisation of pore and surface area showed that all three woody biochars provided potential habitats for soil microorganisms due to their high porosity and surface areas. The biochars were structurally heterogeneous, varying in porosity and surface structure both within and between the biochar sources. After the 56-d incubation, hyphal colonisation was observed on biochar surfaces and in larger biochar pores. Soil clumping occurred on biochar particles, cementing and covering exposed biochar pores. This may have altered surface area and pore availability for microbial colonisation. Transient changes in soil microbial biomass, without a consistent trend, were observed among biochars during the 56-d incubation.

Biochar amendment decreases soil microbial biomass and increases bacterial diversity in Moso bamboo ( Phyllostachys edulis ) plantations under simulated nitrogen deposition

“…In addition, biochar amendment reversed the reduction in soil microbial diversity caused by N addition (figure 3). One possible explanation may be that biochar created a favorable habitat for microbial colonization due to the large surface area and porous structure of biochar and its physicochemical properties, such as alkalinity, which might improve pH, water holding capacity and CEC (Jaafar et al 2015). These results support our second hypothesis by suggesting that biochar amendment could offset the positive effects of N deposition on MBC and the negative effects on bacterial diversity.…”

Thermogravimetric analysis and carbon stability of chars produced from slow pyrolysis and hydrothermal carbonization of manure waste

“…Table 3 shows SBET, Vmicro, Vmeso and Vmacro. The surface area and porous structure provide potential habitats and are important factors in the char interaction with soil microorganisms and consequently, with their stability [ 40]. The two hydrochars showed higher surface areas than the pyrochars.…”

Biochar Application in Malaysian Sandy and Acid Sulfate Soils: Soil Amelioration Effects and Improved Crop Production over Two Cropping Seasons

“…The authors explained the positive effects based on an improvement of soil physical properties, porosity, water holding capacity, pH and CEC resulting from the amendment of biochar. Jaafar et al [18] studied the response of arbuscular mycorrhizal towards biochar soil amendment and reported that application of 50 t/ha of biochar gave significantly higher colonization of mycorrhizal root for subterranean clover and wheat. Kameyama et al [19] reported that the addition of 1%-10% wt sugarcane bagasse biochar produced at 800˝C to two types of sandy soils in Japan increased the water retention capacity of the soils proportionally to the amount of biochar added.…”