In 2022, this project delivered a desktop review on current and emerging substrate options for hydroponic berry production in Australia. The findings and recommendations will inform the rubus industry about what options are feasible for the Australian production context.
The research found that wood-fibre substrates most likely present a great opportunity for rubus growers to diversify their substrate use. Further development and refinement of the substrates and their use as well as regional production options (circular economy) will be required along with production, economic and emission assessment data collection and analysis.
Long-term (over 3-4 production years) controlled trials are required to quantify any potential yield or production impacts when using 100 per cent wood-fibre in comparison with coir and to understand any required changes in management practices including potentially mixing wood fibre with other materials e.g. spent coir or substrates identified in this study.
Desktop analysis and consultation
A national and global scan was undertaken to identify and analyse previously and currently used growing media, as well as emerging alternatives. Consultation with growers, substrate producers and industry representatives were undertaken in addition to an extensive desktop review. The review considered all potential substrate alternatives, not only those which had been used or developed specifically for rubus hydroponic production.
SWOT analyses were undertaken on all growing media options identified as potentially suitable. A comparative gross margin analysis model was constructed to assess production systems using coir against a wood-fibre substrate which was identified as the most viable replacement at this stage.
Economic analysis and emissions
An economic threshold analysis was included to show at which substrate and berry price and yield the gross margin would not be adequate to cover variable costs (cost of sales). The analysis was based on accessible financial data for production in coir substrates, both published and obtained from industry sources; a set of assumptions had to be made for the wood-fibre substrate, given it had not yet been used for commercial Rubus production.
The gross margin analysis demonstrated that wood-fibre is likely to be cost-competitive when compared to coir assuming yield performance and durability as well as management of spent substrate are equivalent to coir. A high-level emission assessment was included for coir transport.