Biochar and chitin amendments for tomato substrates in commercial production: evaluation of the potential to enhance growing media sustainability
Biochar and chitin are candidate materials for enhancing the performance of hydroponic growing media as up-cycled feedstocks. While addressing the need to reduce the carbon footprint of intensive production systems, their use needs to be optimized in commercial practice in sustainable growing media. Novel blends generated in the Horti-blueC project using these materials were evaluated in hydroponic tomato production in laboratory and commercial trials. A prototype coir/wood fiber blend was compared with blends amended with 2 g L‑1 chitin or biochar for a tomato crop. Yield in the biochar treatment exceeded that of the unamended coir by 42.5% in laboratory trials, and chitin treatments increased yield by 12.8%. In plants grown with reduced nitrogen inputs neither amendment impacted yield. Reduced canopy area and leaf chlorophyll content in the base prototype blend were mitigated by biochar amendment. Plants were inoculated with Agrobacterium tumefaciens and examined for tomato root mat disease development, although no significant differences were seen between blends. In two commercial scale trails the biochar blend achieved comparable yield outputs to a commercial coir control, but marginally lower yields were reported against rockwool. Differences in crop management and substrate pH/conductivity may have impacted yield. Substrates amended with biochar exhibited the potential to maintain or improve productivity of tomato by improving root-zone conditions. As there are discrepancies between development and commercial deployment, agronomic practices may require modification to align fertigation management with substrate requirements to optimise performance when incorporating biochar and chitin. These materials should be explored further to generate industry-relevant evidence on how to optimise their use.
Gage, E., Kaye, D. and Mulholland, B. (2021). Biochar and chitin amendments for tomato substrates in commercial production: evaluation of the potential to enhance growing media sustainability. Acta Hortic. 1317, 9-16
commercial yield, fruit quality, nutrients, biomass, root mat disease