Biochar impact on development and productivity of pepper and tomato grown in fertigated soilless media

Abstract

The impact of additions (1-5% by weight) of a nutrient-poor, wood-derived biochar on pepper (Capsicum annuum L.) and tomato (Lycopersicum esculentum Mill.) plant development and productivity in a coconut fiber:tuff growing mix under optimal fertigation conditions was examined. Pepper plant development in the biochar-treated pots was significantly enhanced as compared with the unamended controls. This was reflected by a system-wide increase in most measured plant parameters: leaf area, canopy dry weight, number of nodes, and yields of buds, flowers and fruit. In addition to the observed increases in plant growth and productivity, the rhizosphere of biochar-amended pepper plants had significantly greater abundances of culturable microbes belonging to prominent soil-associated groups. Phylogenetic characterization of unique bacterial isolates based on 16S rRNA gene analysis demonstrated that of the 20 unique identified isolates from roots and bulk soil from the char-amended growing mix, 16 were affiliated with previously described plant growth promoting and/or biocontrol agents. In tomato, biochar treatments positively enhanced plant height and leaf size, but had no effect on flower and fruit yield. The positive impacts of biochar on plant response were not due to direct or indirect effects on plant nutrition, as there were no differences between control and treatments in leaf nutrient content. Nor did biochar affect the field capacity of the soilless mixture. A number of organic compounds belonging to various chemical classes, including n-alkanoic acids, hydroxy and acetoxy acids, benzoic acids, diols, triols, and phenols were identified in organic solvent extracts of the biochar. We conjecture two related alternatives to explain the improved plant performance under biochar treatment: (i) the biochar stimulated shifts in microbial populations towards beneficial plant growth promoting rhizobacteria or fungi, due to either chemical or physical attributes of the biochar; or (ii) low doses of biochar chemicals, many of which are phytotoxic or biocidal at high concentrations, stimulated plant growth at low doses (hormesis).

Biochar as a Substitute for Vermiculite in Potting Mix for Hybrid Poplar

“…Previous research by Graber et al [15] showed that pepper and tomato plant growth were significantly enhanced by the addition of biochar to their potting mix. They concluded that this was not due to improved nutrient availability (based on a lack of significant differences in leaf nutrient concentrations), and hypothesized instead that the biochar may have stimulated beneficial soil microbes and/or contained nonnutrient chemicals that directly stimulated plant growth.…”

“…For example, Dumroese et al [14] found that peat moss amended with biochar pellets showed improved hydraulic water conductivity and water availability, and Graber et al [15] found that a potting mix amended with biochar enhanced tomato and pepper plant growth. Moreover, greenhouse applications present important advantages over field applications; for instance, avoiding the issues of reduced herbicide efficacy that may occur with field applications [16][17][18].…”

Substitution of peat moss with softwood biochar for soil-free marigold growth

“…At low amendment (1-5%) or substitution (< 25%) rates, BC has been found to maintain or improve plant growth as a result of increased nutrient availability (Headlee et al, 2014), reduced nutrient and water loss (Altland and Locke, 2013;Beck et al, 2011;Graber et al, 2010), and amelioration of peat acidity (Bedussi et al, 2015), though these effects may be BC-specific due to feedstock and pyrolysis influences on BC properties (McBeath et al, 2015;Zhao et al, 2013).…”

Biochar is a growth-promoting alternative to peat moss for the inoculation of corn with a pseudomonad

“…The chemical and physical characteristics of biochar, a product of biomass pyrolysis, such as high porosity, water holding capacity, and elevated concentrations of organic carbon and nutrients, have had positive effects on soil quality and plant growth (Xu et al 2012;Graber et al 2010;Major et al 2010). Postma et al (2013) showed that animal bone charcoal can be colonized by bacteria to mobilize phosphate and control plant pathogens.…”