Impact of Biochar Application to Soil on the Root-Associated Bacterial Community Structure of Fully Developed Greenhouse Pepper Plants

Abstract

Adding biochar to soil has environmental and agricultural potential due to its long-term carbon sequestration capacity and its ability to improve crop productivity. Recent studies have demonstrated that soil-applied biochar promotes the systemic resistance of plants to several prominent foliar pathogens. One potential mechanism for this phenomenon is root-associated microbial elicitors whose presence is somehow augmented in the biochar-amended soils. The objective of this study was to assess the effect of biochar amendment on the root-associated bacterial community composition of mature sweet pepper (Capsicum annuum L.) plants. Molecular fingerprinting (denaturing gradient gel electrophoresis and terminal restriction fragment length polymorphism) of 16S rRNA gene fragments showed a clear differentiation between the root-associated bacterial community structures of biochar-amended and control plants. The pyrosequencing of 16S rRNA amplicons from the rhizoplane of both treatments generated a total of 20,142 sequences, 92 to 95% of which were affiliated with the Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes phyla. The relative abundance of members of the Bacteroidetes phylum increased from 12 to 30% as a result of biochar amendment, while that of the Proteobacteria decreased from 71 to 47%. The Bacteroidetes-affiliated Flavobacterium was the strongest biochar-induced genus. The relative abundance of this group increased from 4.2% of total rootassociated operational taxonomic units (OTUs) in control samples to 19.6% in biochar-amended samples. Additional biochar-induced genera included chitin and cellulose degraders (Chitinophaga and Cellvibrio, respectively) and aromatic compound degraders (Hydrogenophaga and Dechloromonas). We hypothesize that these biochar-augmented genera may be at least partially responsible for the beneficial effect of biochar amendment on plant growth and viability.

Dynamics of microbial community composition and soil organic carbon mineralization in soil following addition of pyrogenic and fresh organic matter

“…Recent research has only begun to identify PyOM effects on soil microbial communities, and it is clear that PyOM additions to soil can induce changes in soil microbial community composition. Most current evidence has been gathered using fingerprinting approaches, such as terminal restriction fragment length polymorphism (Bingeman et al, 1953;Jin, 2010;Kolton et al, 2011) or denaturing gradient gel electrophoresis (Kolton et al, 2011;Chen et al, 2013), or by surveying phospholipid fatty acids to assess microbial diversity at low phylogenetic resolution (Dunavin, 1969;Jindo et al, 2012;Gomez et al, 2014;Watzinger et al, 2014;Mitchell et al, 2015). In addition, clone libraries targeting functional genes (Song et al, 2014) and some highthroughput DNA sequencing approaches have been applied to survey microorganisms in PyOM systems.…”

Soil respiration, pH and EC as influenced by biochar

“…Kolb et al (2009), Anderson et al (2011) and Lehmann et al (2011) reported that changes in soil properties with biochar in turn differentially influenced microbial activity and community structure. Kolton et al (2011) and Graber et al (2010) established that changes in soil microbial communities bring about changes in nutrient transformations which can have impact on crop growth. Our results are however contrary to the belief that biochar use as soil amendments can increase C storage (Woolf et al, 2010 ) and hence mitigate CO 2 emission.…”

Mitigating Greenhouse Effect in India through Gradual Shift to Renewable Energy

“…A change in land-use patterns or inefficient management of soil, including ploughing, drainage and excessive fertilizer input, leads to loss of soil carbon which reduces crop productivity 62 . A solution to improve soil sink capacity is through application of biochar augmented with microbes which help in the uptake of nutrients by the crop 63,64 . The avoided GHG emission through this method would translate into reduced fertilizer application due to improvement in soil fertility 65 .…”