A biotic strategy to sequester carbon in the ornamental containerized bedding plant production: A review

Identifying options of climate change mitigation is of global interest to researchers. Whereas wide range of techniques of reducing greenhouse gas (GHG) emissions and carbon sequestration have been studied in row crops and forest systems, little research has been done on the ornamental horticulture. The ornamental industrial sector has indeed some negative impacts on the global environment, but also presents opportunities to reduce GHG emissions and increase C sequestration. Thus the objective of this study was to synthesize the potential contributions of some substrates used in the horticultural sector to carbon sequestration. The specific focus of the review is on the possible use of compost, vermicompost and biochar as soilless substrate substitutes for containerized ornamental plants production. Around 11 million kilograms of sphagnum peat moss are used annually in the world for horticultural production. Therefore, the potential of using compost, vermicompost and biochar as growing media is assessed on the basis of data from greenhouse studies. Peat-based substrate can be substituted up to 30% to 35% by compost or vermicompost and up to 20% to 25% by biochar. Some examples from field studies are included to conduct the life cycle assessment of using these growth media. An estimate of C storage on the long-term basis in soil indicates up to 3 million tons of CO2 equivalent as the maximum C potential storage per year in the global productive sector if the peat-based growing media are substituted by compost/vermicompost and biochar at the ratios mentioned above. Finally, synergies between compost vermicompost and biochar are discussed when these materials are combined as growing media additives and research gaps in this area of activity have been identified for further research.