Scientists from Riga Technical University (RTU) have conducted research proving that the use of peat substrate in horticulture has a significantly lower – up to seven times lower – total environmental impact than the horticulture substrate alternatives most commonly used in the European Union. The scientific publication of the research was published in October in one of the world's most influential scientific journals in the field of environmental science, the Journal of Cleaner Production. RTU conducted the study based on a life cycle analysis of peat substrate at Laflora, one of Latvia's largest peat extraction and processing companies.
A significant volume – 86% – of substrates used in the EU for growing food, tree seedlings, and ornamental plants are peat substrates, a third of which is supplied by Latvian peat. Although alternatives to replace peat substrates have been sought for decades, the total environmental impact of other alternative growing substrates has not been evaluated.
The aim of the RTU study was to evaluate the impact of horticultural peat substrate and the most commonly used alternatives – coconut coir and rock wool substrates – on human health, climate change, resources, and ecosystem quality.
Peat substrates have a lower environmental impact than their alternatives
By performing an environmental life cycle analysis on three horticultural substrates – peat, coconut coir, and rock wool – scientists concluded that coconut coir substrate has the highest total environmental impact at 48.51 mPt (milliEcoPoints – an internationally used ecological indicator), followed by rock wool substrate at 10.6 mPt, while the peat substrate indicator is only 6.79 mPt. This means that the use of peat substrate in horticulture has up to seven times less total environmental impact than, for example, coconut coir substrate.
A significant aspect of the overall assessment is the comparison of GHG emissions generated by the substrates, or their impact on global warming: the emissions generated by coconut coir substrate per 1 m3 of substrate reach 47 kg of CO2 equivalent, emissions from rock wool are 32.1 kg of CO2 equivalent, and emissions from peat substrate are 20.2 kg of CO2 equivalent.
Scientifically substantiated environmental profile of peat substrate
To determine the total environmental impact of horticultural peat substrate, RTU carried out a full life cycle analysis, or a so-called “cradle-to-grave” assessment. Covering all processes in the life cycle of peat substrate – preparation of peat fields, peat extraction, processing, transport to end consumers, use in horticulture, and utilization, i.e., the end-of-life stage – the generated environmental impacts were assessed, and an environmental profile for the peat substrate of the extraction and processing company Laflora was created.
This made it possible to identify the stages in the peat substrate life cycle that create the greatest environmental impacts – these are the transport of the peat substrate to the end consumers, which is linked to diesel fuel consumption by road transport, and peat extraction, where impacts are related to the opening of peat bogs. Scientists recommend replacing road transport with rail in the distribution of peat products, as well as shortening the preparation of peat fields and the peat extraction process as much as possible to carry out land recultivation, thereby reducing the impact on the ecosystem.
“The environmental life cycle analysis (Environmental Life Cycle Analysis) used in the study is a globally recognized scientific method for assessing a product's environmental impact throughout its entire life cycle, which was carried out in accordance with ISO standards using IPCC guidelines, the Ecoinvent database, and the IMPACT 2002+ method for impact assessment. We are pleased to publish the results of our study in one of the industry's most influential scientific journals, the Journal of Cleaner Production, which covers interdisciplinary research on cleaner production and sustainable development,” states Agris Kamenders, Associate Professor at the Institute of Energy Systems and Environment at Riga Technical University.
“This study provides a solid foundation for the sustainability of Laflora and reaffirms that peat is part of the European Green Deal and helps to reach climate neutrality goals. There are no suitable substitutes for peat substrate in horticulture. When making political decisions in Europe and here in Latvia, it is important to rely on scientific research. I thank RTU for this high-quality study!” says Uldis Ameriks, head of the peat extraction and processing company Laflora.
The scientific publication of the RTU study “Peat production for horticulture in the Latvian context: sustainability assessment using Life Cycle Analysis modeling” in the Journal of Cleaner Production is available here: https://www.sciencedirect.com/science/article/pii/S0959652622041312