Land in the Scottish Highlands is usually regarded as being too poor for farming anything other than sheep. A trial project based at the Sustainable Ecological Earth Regeneration (SEER) Centre is demonstrating a technique using rock dust to bring fertility back to the soil – with dramatic results.
Rock dust is a by-product of the quarrying industry and would normally be considered a waste to be sent to landfill sites and sent to landfill sites until the Landfill tax was introduced.. However, it contains more than 78 mineral and trace elements that, through a process of remineralisation, can be used to improve soil fertility. This process came to prominence with the publication of Survival of Civilisations by American scientists, John Hamaker and Don Weaver, in 1984. Their theory was that during glaciation, as glaciers passed over land, rocks were crushed, releasing minerals and trace elements onto the land and, over time, deep fertile soils were created on Earth to support life during the interglacial. There have been 25 glaciations and interglacials in the last 2.5 million years. These are Earth’s fertility cycles.
Benefits of remineralisation
- Provides slow, natural release of elements and trace minerals.
- Increases the nutrient intake of plants.
- Increases yields.
- Rebalances soil pH.
- Increases microbial and earthworm activity.
- Builds humus.
- Prevents soil erosion.
- Increases the storage capacity of the soil.
- Increases resistance to insects, disease, frost, and drought.
- Produces more nutritious crops.
- Enhances flavour in crops.
- Decreases dependence on fertilisers, pesticides, and herbicides.
Inspired by this publication a dedicated couple, Cameron and Moira Thomson, have been experimenting over the past 20 years with soil regeneration techniques. They first opened their gardens to the public in 1984, and contacted governments and scientists about their work. They were offered a larger site in Scotland at Pitlochry by a local landowner and moved there in 1996. The soil was very poor – infertile and poorly drained. No crops had been grown there for almost 50 years. They set about the challenge of improving this soil.
In 1997 they set up a charitable trust, the Sustainable Ecological Earth Regeneration (SEER) Centre. This centre is a demonstration area for organic production using remineralised soil. It is used by farmers and growers, environment, waste and recycling sectors, local schools, educational and health establishments. Additionally, it assists the waste industry by reducing the quantities of waste going to landfill locally. The SEER Centre receives as much rock dust as they need from the local Collace Quarry, operated by local contractor, Tayside Contracts.
This rock dust is particularly high in minerals as it comes from volcanic rock. When it is applied to the soil the natural weathering process is accelerated, depending on how much rock dust is applied. The weathering process continues each year as microbial action decomposes vegetation. This releases organic acids that percolate down through the topsoil and dissolve particles of stone, freeing the minerals and trace elements. This ensures that in following growing seasons these mineral and trace elements are available for future crops. Another benefit comes from the fact that the calcium and magnesium content in the rock dust combines with atmospheric carbon, forming carbonates that can then be captured in the soil and recycled by life in the soil. The Thomsons believe that, remineralised soils take carbon out of the atmosphere more effectively than normal soils, and this could have a major impact in reducing the quantities of the harmful greenhouse gas, carbon dioxide, in the atmosphere.
At the SEER centre trial plots were created with separate terraces – some containing poor soil only, some with poor soil covered with rock dust which were left for the microbes and worms to process naturally, and the others with compost only. They wished to compare the resulting crops in terms of both yield and appearance. Now their six acres (2.4 hectares) are producing amazing yields of fruits and vegetables that have high nutritional value because of the richly mineralised soils they grow in.
Additional trials have been carried out using a mixture of rock dust and Dundee City Council’s municipal compost to demonstrate potential beneficial uses for recycling municipal composts in soil creation and soil improvement. Municipal composts could soon be causing problems for waste authorities as organic waste will not be allowed into landfill in future because it produces methane, another greenhouse gas, as it rots down. When rock dust is added to green waste it improves and accelerates the composting process. The end product is an organic fertiliser, not a soil conditioner. If it is proved that adding rock dust to municipal green waste does improve compost quality and fertility, rockdust could add huge value to the composting industry. So, creating a useful product from these wastes is of particular environmental value – especially as the Thomsons have found the combination of rock dust and mature compost means they can grow bumper, mineral-rich produce. This SEER mixture improves the soil as well as reducing pests and diseases, so there is much less need for chemical fertilisers and pesticides Bags of SEER Rockdust™ are now commercially available.
Benefits of using Rockdust™
Boosts plant growth
- Dramatically increases crop yield
- Improves disease resistance of crops
- Extends shelf-life of crops
- Improves flavour of edible crops
- Improves nutritional value of crops
Benefits the soil and the environment
- Improves fertility of the soil
- Binds up pollution caused by chemical fertilisers
- Improves biodiversity
- Increases composting rates
- Increases heat generated during composting
- Binds up ammonia in the soil
- Reduces composting odours
- Improves compost fertility
- Benefits the national waste strategy
- Improves health of those eating food crops
Reduces greenhouse gases via carbon sequestration
- When the Rockdust™ is added to soil the trace elements and minerals bond with CO 2 in the atmosphere.
The SEER Centre received £76,000 in 2004 from the Scottish Executive to maintain the 6 acres of terraced demonstration gardens.
The Thomsons have found that their land has been transformed from infertile, poorly drained soil only suitable for grazing, into land able to produce bumper crops. The environment has benefited as chemical fertilisers have not been used and biodiversity has been established.
The SEER Research Project received over £95,000 funding, through the Landfill Tax Credit Scheme, in November 2003. This enabled them to set up the first ever UK field trials investigating rockdust in agriculture. Funding will be sought to continue it in future years.
‘It is very rare to find an idea like this that can confer so many human benefits. The potential for soil remineralisation to improve the quality of our food chain by putting minerals back into our food; to improve the physical condition of soil when used with organic material such as compost; and most interestingly the potential that remineralised soils may contribute to addressing global climate change by locking CO2 into soils is profound. Many of these require further study and the SEPA are working closely with the SEER Centre to develop these potential viable benefits.’
John Ferguson, Waste and Resources Strategy Unit Manager, SEPA
Through partnership with the University of Glasgow and advisers from the waste management industry and the Scottish Environment Protection Agency (SEPA), a rigorous three-year field trial is being carried out in the adjacent seven-acre (2.8 hectare) flat field. They will evaluate remineralisation methods, their effects on the soils, plant yields, carbon sequestration by soils, nutrient status of crops and the potential of markets for composted materials using rock dust.
It is hoped that lessons learned from this can be put to use to improve soils around the world.
Hands On would like to thank Moira Thomson of the SEER Centre for help and advice in putting together this case study.
Sustainable Ecological Earth Regeneration (SEER) Centre www.seercentre.org.uk
Scottish Environment Protection Agency (SEPA) Office
Robin A.K. Szmidt, John Ferguson, ‘Co-utilization of rockdust, mineral fines and compost’, 2004
Remineralize the Earth www.remineralize.org
ITDG Technical Briefs answers.practicalaction.org
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