The use of biochar as an additive for growing media for the production of potted plants requires a sound knowledge of how its properties impact plant biomass production. This study aims at linking physical and chemical properties of biochar with horticultural crop biomass. For this purpose, we incorporated six different biochars into growing medium and grew basil (Ocimum basilicum L.), lettuce (Lactuca sativa L. var. crispa) and pansy (Viola wittrockiana Gams.) for one month in greenhouse conditions. We found that physical and chemical properties of biochars had a significant impact on plant growth. Biochars with low density and high porosity promoted the biomass of basil and lettuce. While nutrient concentration in biochars had no impact on plant growth, lettuce and pansy biomasses decreased with increasing biochar pH and basil biomass decreased with increasing biochar electrical conductivity. By identifying which biochar properties influence plant biomass, our study allows selection of the biochars which are the best suited for incorporation into growing media.

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