See Pages 40 to 44 January 2013

Rising out of the dust January40 JANUARY 2013 2013 see Pages 40www .kitchengarden.co.ukto 44 Eat your minErals Minerals and trace elements are essential to human health, and the mineral content of our food has dropped alarmingly. One study, published in Nutrition and Health in 2003, compares the mineral content of a range of foods, including 27 vegetables, over the period 1940 to 1991. Taking the 27 vegetables overall, sodium dropped by an average of 49%, potassium by 16%, magnesium by 24%, calcium by 46%, iron Cameron spreads rock dust on half of Terrace four for a growing trial. by 27% and copper by 76%. The study notes that you would need to have eaten 10 tomatoes in 1991 to obtain the same amount of copper as one would have given you in 1940. It cannot be proved that this is a direct result of the loss of minerals from the soil, nor that the minerals in crops were already in decline before 1940, since there is insufficient earlier data. Agrochemicals – introduced around 1940 – may well be a factor. However, an analysis comparing one of the Thomsons’ Rockdust-grown carrots with a chemically-grown supermarket one does suggest that crops grown in remineralised soil are correspondingly mineral-rich. It found that the Thomsons’ carrot had up to 10 times the mineral content: 14,380mg of calcium per kilogram as opposed to 4815mg, for instance, and 290.3mg of iron compared to 39.77mg. How to usE became a committed supporter, and ended up trialled and tested sEEr rockdust offering them a house and as much land as they In terms of demonstrating the effectiveness of needed. In 1997 they moved to Perthshire and set rock dust, however, there was a problem. ✤ In the garden: Lightly fork it into bare about creating a demonstration garden. Scientists visiting the garden at the end of the soil in spring or autumn. Add compost at Despite its idyllic location, the site was first growing season took the view that the the same time, and regularly thereafter, challenging: infertile moorland, 1000ft above sea Thomsons’ impressive results were down to the to build the soil’s humus content and level, subject to cold winds, harsh winters and a compost rather than the dust. Their response was encourage the worms and micro- short growing season. But, says Moira, by the to build new terraces in which to run trials organisms which break the dust down. same token it was the perfect place to comparing the yield from soil only, compost only, ✤ In raised beds and containers: Combine demonstrate rock dust’s transformative potential. soil and rock dust, and compost and rock dust – Rockdust with compost or leaf-mould to “If you can do it here, you can do it anywhere.” and the results were, they feel, conclusive. create a growing medium. You can also They knew from the outset that the existing Trial after trial has shown a similar yield from beds sprinkle it on to the surface of soil was a non-starter. After millennia of erosion, with rock dust and compost and beds with just rock containers as an easier alternative to all that was left on their hillside was a mixture of dust added to the poor local soil. While very hungry replacing the soil. boulders, pebbles and silt, with a shallow crops like brassica showed better results from a ✤ As a potting compost: Mix Rockdust covering of soil with a pH of 4.5. The natural compost and rock dust mix, trials with crops with leaf-mould or worm compost. vegetation is heather and rushes, and local including peas, potatoes and greenhouse tomatoes ✤ As a compost activator: Rockdust farming is restricted to sheep. The plan was to showed a comparable increase in yield from just soil encourages microbial activity and create new soils from a blend of rock dust and and rock dust within a single growing season. The therefore a higher temperature in the compost, which Dundee Council donated by the Thomsons are not recommending that you add compost heap, accelerating lorryload. Because the site is on a slope, they built rock dust to poor soil without also adding organic decomposition and maturation, locking terraces, edging them with stones reclaimed matter; their aim was simply to prove that it is the in more nitrogen and improving the from broken dykes. “We mixed the compost dust that makes the difference. fertility of the compost. and rock dust by hand, 220 tonnes, two shovels Rock dust relies on the activity of worms and ✤ In a worm bin: and a wheelbarrow. It took us three months to soil microbes, which break down the particles and ingesting Rockdust make the first two terraces, by ourselves, with the make the minerals available for plant uptake. You helps worms to kids helping.” can apply small quantities annually, but the ideal, digest organic No sooner were they finished than they were say the Thomsons, is to apply the maximum dose material, so the into the growing season, and their first crops were of 5kg per square metre at the outset. This will process is quicker, everything they had hoped for. “Hardly any insect keep the soil supplied for five to 10 years. It seems and the resulting damage, hardly any disease, hardly any withered that the worms and microbes respond more compost is leaves, and chock-a-block vegetation. The health enthusiastically to a fully stocked soil, resulting in mineral-enriched. and vigour of the plants was incredible.” a greater increase in fertility and yield. www.kitchengarden.co.uk JANUARY 2013 43 Municipal compost and rock dust: the raw ingredients for soil creation. Geological records show that previous interglacials lasted between 9600 and 11,500 The Thomson family on their new site years; the present one is around 10,800 years old. in 1996, before the project began. The minerals left behind by the glaciers are mostly gone, used up by life on earth or leached into the an inorganic product to the soil seemed to And that, say the Thomsons, is only the start of sea. Only near active volcanoes is the soil still rich undermine the fundamental importance of it. If remineralisation was carried out on a global in minerals, brought up from inside the earth by enriching soil organically. I was reminded that soil scale, it could transform agriculture and the eruptions. Soil remineralisation is simply a way of is a combination of organic and inorganic environment. Remineralised soil could, they say, mimicking the process of glaciation (or the action material, derived from the breakdown of organic grow more food, reducing world hunger; it could of a volcano, minus the inconvenience). matter and the weathering of rocks respectively. grow abundant crops organically, replacing My other reservation was that the use of rock SEER Rockdust is a natural product which leaves no agrochemicals; and the mineral-rich food would dust felt too akin to a chemical quick fix. Adding toxic residues, and it has been approved for use in produce healthier people. In conjunction with organic systems. That said, the Thomsons are keen organic enrichment, rock dust could be used to to emphasise that it is a quick fix – of the best sort. build new soils in barren areas where food cannot Eco issuEs “By spreading rock dust, you are doing in minutes be grown at present. It is also claimed that there what the earth takes thousands of years to do.” is the potential to mitigate climate change, Rock dust is a byproduct of quarrying, so Analyses have shown that SEER Rockdust because adding rock dust to soil increases its by using it in your garden you are also contains 78 minerals and trace elements – some capacity to absorb carbon. creating a use for a waste product. An two-thirds of all the elements in the periodic obvious concern, however, is whether table. Used in the kitchen garden, say the The oasis in the glen existing quarrying produces enough waste Thomsons, it produces more nutritious crops, The Thomson’s had found their mission. Over the to supply an expanding market. If with a higher concentration of minerals. Crops next decade, they continued growing and additional quarrying were needed to are also bigger and juicier, with a better flavour campaigning, “spreading the word and the produce dust for remineralisation, this and a longer shelf life. Yields are higher, and dust”, and by the mid-1990s they needed a would have a detrimental impact on the plants are more pest and drought resistant. bigger canvas to work on. I asked how they found landscape as well as a hefty carbon Ornamentals grown on remineralised soil have their present site. “It found us,” says Moira. The footprint. Moira was quick to reassure me; brighter flowers and a better scent. landowner saw them featured in the Scotsman, quarrying produces a vast amount of waste dust, most of which is simply stockpiled. “There are so many quarries and they don’t know what to do with this stuff. It is a valuable resource, they just haven’t recognised it as such.” However, not all quarries produce volcanic rock, and even if you do have a local basalt quarry, going along with a bag and a shovel is not recommended. SEER’s Rockdust has been rigorously analysed to ensure that the minerals and trace elements it contains are suitable for soil remineralisation; other quarry dusts may be lacking in essential minerals, or contain toxic elements or heavy metals. At the moment all SEER Rockdust comes from one Scottish quarry, whence it is shipped to customers across Europe, and that raises obvious environmental issues.

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