Abstract
While biochar use in agriculture is widely advocated, how the effect of biochar on plant growth varies with biochar forms and crop genotypes is poorly addressed. The role of dissolvable organic matter (DOM) in plant growth has been increasingly addressed for crop production with biochar. In this study, a hydroponic culture of rice seedling growth of two cultivars was treated with bulk mass (DOM-containing), water extract (DOM only), and extracted residue (DOM-free) of maize residue biochar, at a volumetric dosage of 0.01, 0.05, and 0.1%, respectively. On seedling root growth of the two cultivars, bulk biochar exerted a generally negative effect, while the biochar extract had a consistently positive effect across the application dosages. Differently, the extracted biochar showed a contrasting effect between genotypes. In another hydroponic culture with Wuyunjing 7 treated with biochar extract at sequential dosages, seedling growth was promoted by 95% at 0.01% dosage but by 26% at 0.1% dosage, explained with the great promotion of secondary roots rather than of primary roots. Such effects were likely explained by low molecular weight organic acids and nanoparticles contained in the biochar DOM. This study highlights the importance of biochar DOM and crop genotype when evaluating the effect of biochar on plants. The use of low dosage of biochar DOM could help farmers to adopt biochar technology as a solution for agricultural sustainability.
Highlights
Biochar has been known generally as a carbon-rich solid residue of biomass pyrolysis in an oxygen-limited environment in a temperature range typically of 350–600◦C (Boateng et al, 2015)
Washed biochar (WBC) and biochar water-extract (BCE): the above biochar material was extracted with hot water to obtain a BCE, but the residue was left as WBC free of dissolvable organic matter (DOM)
Our present study suggested the addition of biochar at low dosage (
Summary
Biochar has been known generally as a carbon-rich solid residue of biomass pyrolysis in an oxygen-limited environment in a temperature range typically of 350–600◦C (Boateng et al, 2015). Unlike charcoal or char ash formed under pyrolysis up to 900◦C, biochar could recover most nutrients and preserve physical structure with nano-pores inside (Pan et al, 2015). The amendment of biochar to soil has widely shown positive changes in plant growth and crop productivity (Liu et al, 2013). Such effect was addressed with manipulation of plant metabolic processes
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