Rock flour
Rock flour, or glacial flour, consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion or by artificial grinding to a similar size. Because the material is very small, it becomes suspended in meltwater making the water appear cloudy, which is sometimes known as glacial milk.[1][2]
When the sediments enter a river, they turn the river's colour grey, light brown, iridescent blue-green, or milky white. If the river flows into a
Formation
Although clay-sized, the flour particles are not
Agricultural use
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Rock flour, artificial or natural, is a source of
The igneous rocks basalt and granite often contain the highest mineral content, whereas limestone, considered inferior in this consideration, is often deficient in the majority of essential macro-compounds, trace elements, and micronutrients.
Background
Soil remineralization (in the sense of re-incorporating minerals, different from remineralisation in biogeochemistry) creates fertile soils by returning minerals to the soil which have been lost by erosion, leaching, and or over-farming. It functions the same way that the Earth does: during an Ice Age, glaciers crush rock onto the Earth's soil mantle, and winds blow the dust in the form of loess all over the globe. Volcanoes erupt, spewing forth minerals from deep within the Earth, and rushing rivers form mineral-rich alluvial deposits.
Rock dust is added to soil to improve
History
While this originally was an
Research
SEER's research claims that the benefits of adding rockdust to soil include increased moisture-holding properties in the soil, improved
A 2022 study found that basalt dust improved soil fertility and increased available phosphorus, potassium, calcium and magnesium levels compared to soil without the basalt dust in a period of several months.[5]
Composition
Element | Unit | |
---|---|---|
calcium | %w/w | 6.44 |
iron | %w/w | 10.5 |
magnesium | %w/w | 6.54 |
sulfur | %w/w | 0.21 |
potassium | %w/w | 1.25 |
phosphorus | mg/kg | 3030 |
cobalt | mg/kg | 35 |
copper | mg/kg | 43 |
manganese | mg/kg | 790 |
molybdenum | mg/kg | <5 |
zinc | mg/kg | 92 |
silicon | %w/w | 21.6 |
Silicon is thought to be the major element effecting the strength of cell wall development. However it is the amount of available silica that has a dramatic effect on the plant strength and subsequent health. To highlight this, plants that are grown in very sandy soils, (being high in non available silica), often require a silica based fertiliser to provide available silicon.[citation needed] Silicon comes in silicon multi-oxide molecules (e.g. SiO2, SiO4, SiO6, and SiO8). Each molecule shape is thought to pack in different ways to allow different levels of availability.
Often phosphorus is locked in soils due to many years of application of traditional
The
The calcium and magnesium in high quality have the ability to neutralise pH in soils, in effect acting as a liming agent.[citation needed]
Application
Rock dust can be applied to soil by hand application, via broadcast spreader or by fertigation. Where possible the rockdust can be worked into the ground either physically or by using water to wash in.
In some soils which display poor levels of nutrients, application rates of 10 tonnes per hectare are required. In Australia, namely the Riverland, Riverina, Langhorne Creek[where?], Barossa and McLaren Vale[where?] regions, rates are 3–5 tonnes per hectare. In a garden application, this might equate to 400 grams per square metre.
See also
- Diatomaceous earth
- Greensand, used as a source of potassium
- Organic farming
- Organic fertilizer
- Phosphorite, also called rock phosphate
- Soil conditioner
References
- ^ "Glossary of Terms: G: Glacial Milk" PhysicalGeography.net
- ISBN 978-1-4020-4551-6
- ^ Remineralization Might Save Us From Global Warming, The Independent, Paul Kelbie, 21 March 2005
- ^ De Silva, Meragalge Swarna Damayanthi Luxmei (March 2007). "The effects of soil amendments on selected properties of tea soils and tea plants (Camellia sinensis L.) in Australia and Sri Lanka". James Cook University. Retrieved 25 April 2015.
- doi:10.1016/j.jafr.2022.100443.)
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: CS1 maint: multiple names: authors list (link
External links
- Remineralize the Earth – "non-profit organization incorporated to disseminate ideas and practice about soil remineralization"
- Julius Hensel by John Mann
- The USGS Glossary of Glacial Terminology