Biochar: Black diamond to improve plant performance and bacterial composition in growing medium

Citation

Poster presented at The third Global Soil Biodiversity Conference in 2023.

Résumé en langage clair

Peat is the most common substrate used as a growing medium in horticulture. However, the physicochemical properties need to be improved by adding aggregates such as perlite for plant growth. These aggregates are, however, expensive and not sustainable. To produce cheaper peat-based growing medium (PBGM), alternative materials to substitute part of aggregates have been investigated and biochar, carbon-rich material obtained by thermal combustion of biomass could be an interesting sustainable component.

The aim of our greenhouse trials was to evaluate the effect of substituting perlite in PBGM by three types of biochar on tomato and sweet pepper, growth and yield, on retention of water and fertilizer and on the bacterial diversity found in PBGM.

Results indicated that substituting perlite in PBGM with biochar appears to be a beneficial practice towards sustainable greenhouse production, and this practice merit further investigation with other crops such as indeterminate cultivars.

Résumé

Peat is the most common substrate used as a growing medium in horticulture. However, the physicochemical properties need to be improved by adding aggregates such as perlite for plant growth. These aggregates are, however, expensive and not sustainable. To produce cheaper peat-based growing medium (PBGM), alternative materials to substitute part of aggregates have been investigated and biochar, carbon-rich material obtained by thermal combustion of biomass could be an interesting sustainable component.

The aim of our greenhouse trials was to evaluate the effect of substituting perlite in PBGM by three types of biochar on tomato and sweet pepper, growth and yield, on retention of water and fertilizer and on the bacterial diversity found in PBGM. Biochars tested were derived from maple bark pyrolysed at 550 °C (M550) and 700 °C (M700) and from pine chips pyrolysed at 700 °C (P700). Tomato and sweet pepper plants were grown in a greenhouse and fertigated with mineral fertilizer at full or half of the recommended level for 63 days.

Results indicated that the addition biochar increased tomato and sweet pepper fruit yield. Biochar also increased nutrient retention, while reducing nutrient loss in leachates. In addition, the presence of M700 or P700 biochars significantly increased beneficial bacteria for plant growth84 due to the improvement of physical and chemical properties of PBGM. Therefore, substituting perlite in PBGM with biochar appears to be a beneficial practice towards sustainable greenhouse production, and this practice merit further investigation with other crops such as indeterminate cultivars.