Biochar incorporation in compost for organic growing media

Biochar End Uses - Poster Presentation
Biochar incorporation in compost for organic growing media production

Biopterre - Bioproducts Development Center:  Canada, 
Sébastien Lange
Laura Thériault
Selmene Ouertani
Julie Charbonneau

Berger Peat Moss Ltd.: QC, Canada,
Marc Charland

n Quebec, the organic growing media (OGM) production constitutes an important economic driver, particularly in regions. To make these OGM, peat remains essential but is insufficient to provide sufficient nutrients necessary for plant production. Compost is often added to alleviate this deficit, but its nutritional value remains low and most often, the release of nutrients is not synchronized with plant needs.  In fact, when such OGM are used, nutrients from compost are quickly released. They are therefore not available at the optimal time for plant growth as their requirements are often limited after planting or transplanting. On the other hand, Quebec forestry and construction industries produce lots of wood residues that could be pyrolyzed to produce biochar which could then be used as input in the composting process to enhance nutrient retention and development and fixation of microorganisms’ communities. Thus, this study aims to show that addition of biochar to the other inputs at the beginning of the composting process, renders possible 1) to improve the nutrient content of the resulting mature compost and 2) to optimize the release of nutrients from OGM made with biochar-enriched compost with plant development needs. Such synchronization would allow better nutrition effectiveness and minimize nutrient losses, thus reducing the needs of additional fertilization.  

For this study, three 30-m3 windrows of compost were prepared. The control compost was produced with the original recipe of the industrial partner (including peat, chicken and cow manures as inputs) that is present in its entire commercial OGM series. The other windrows were made of the same inputs as the control, except that 20% v/v of peat was replaced by either of two biochars. One biochar was made from hardwood residues from charcoal production, while the other one was produced from decommissioned wood (sick and dead softwoods).

The results that will be presented aim to help understanding the influence of the biochar addition 1) on the composting process; 2) on the nutrient content of mature compost; and 3) on the dynamics of nutrient release in OGM used for plant production.

Keywords: biochar, compost, nutrient content and release, composting process