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 glacial lake, the lake may appear turquoise in colour as a result. When flows of the flour are extensive, a distinct layer of a different colour flows into the lake and begins to dissipate and settle as the flow extends from the increase in water flow from the glacier during snow melts and heavy rain periods. Examples of this phenomenon may be seen at Lake Pukaki and Lake Tekapo in New Zealand, Lake Louise, Moraine Lake, Emerald Lake, and Peyto Lake in Canada, Gjende lake in Norway, and several lakes (among others, Nordenskjöld and Pehoé) in Chile's Torres del Paine National Park, and many lakes in the Cascade Range of Washington State (including Diablo Lake, Gorge Lake, and Blanca Lake).
Typically, natural rock flour is formed during glacial migration, where the glacier grinds against the sides and bottom of the rock beneath it, but also is produced by freeze-and-thaw action, where the act of water freezing and expanding in cracks helps break up rock formations. Multiple cycles create a greater amount.
Although clay-sized, the flour particles are not clay minerals but typically ground up quartz and feldspar. Rock flour is carried out from the system via meltwater streams, where the particles travel in suspension. Rock flour particles may travel great distances either suspended in water or carried by the wind, in the latter case forming deposits called loess.
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Rock flour, artificial or natural, is a source of plant micronutrients (minerals trace elements) widely used in organic farming practices as a soil conditioner. Synonyms in this case include rock dust, rock powders, rock minerals, and mineral fines.
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.
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 fertility and has been tested since 1993 at the Sustainable Ecological Earth Regeneration Centre (SEER Centre) in Straloch, near Pitlochry, in Perth and Kinross, Scotland. [3] Further testing has been undertaken by James Cook University, Townsville, Far North Queensland. [4]
Thomas J. Goreau who wrote the book Geotherapy believed that mafic/ultra-mafic rock flour had a powerful effect in restoring trace minerals to soils, which increases the health and vigour of the Microorganism, Plantae, Animalia pathway and also sequesters carbon. An early experimenter was the German miller, Julius Hensel, author of Bread from Stones, who reported successful results with steinmehl (stonemeal) in the 1890s. His ideas were not taken up due to technical limitations and, according to proponents of his method, because of opposition from the champions of conventional fertilisers.
John D. Hamaker argued that widespread remineralization of soils with rock dust would be necessary to reverse soil depletion by current agriculture and forestry practice.
While this originally was an alternative concept, increasing mainstream research has been devoted to soil amendment and other benefits of rock flour application: for instance, a pilot project on the use of glacial rock, granite and basaltic fines by the U.S. Department of Agriculture exists at the Henry A. Wallace Beltsville Agricultural Research Center. The SEER Centre in Scotland is a leading source of information on the use of rock dusts and mineral fines. The Soil Remineralization Forum was established with sponsorship from the Scottish Environment Protection Agency and has commissioned a portfolio of research into the benefits of using mineral fines. The Forum provides an interface among research, environmentalists, and industry.
SEER's research claims that the benefits of adding rockdust to soil include increased moisture-holding properties in the soil, improved cation exchange capacity and better soil structure and drainage. Rockdust also provides calcium, iron, magnesium, phosphorus and potassium, plus trace elements and micronutrients. By replacing these leached minerals it is claimed that soil health is increased and that this produces healthier plants.
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]
Greenland rock flour increased yields from corn fields in Ghana and barley fields by 30-50%. Melting ice is depositing one billion tons of rock flour annually; one ton can direct air capture 250 kilograms (550 lb) of carbon. [6]
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 fertilisers. The use of micronutrient-rich fertiliser enables plants to access locked phosphorus.
The elements high in available 2+ valence electrons, calcium, iron and magnesium in particular contribute to paramagnetism in soil which aid in cation exchange capacity.
The calcium and magnesium in high quality have the ability to neutralise pH in soils, in effect acting as a liming agent.[ citation needed ]
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.
Ash is the solid remnants of fires. Specifically, ash refers to all non-aqueous, non-gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash is the non-gaseous, non-liquid residue after complete combustion.
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian.
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment, or hand-tool methods.
A period 3 element is one of the chemical elements in the third row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. All of the period 3 elements occur in nature and have at least one stable isotope.
In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. Minerals are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essential amino acids. The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. The remaining minerals are called "trace elements". The generally accepted trace elements are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, selenium, and bromine; there is some evidence that there may be more.
Plant nutrition is the study of the chemical elements and compounds necessary for plant growth and reproduction, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element is part of some essential plant constituent or metabolite. This is in accordance with Justus von Liebig's law of the minimum. The total essential plant nutrients include seventeen different elements: carbon, oxygen and hydrogen which are absorbed from the air, whereas other nutrients including nitrogen are typically obtained from the soil.
Diatomaceous earth, also known as diatomite, celite, or kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 mm to less than 1 μm, but typically 10 to 200 μm. Depending on the granularity, this powder can have an abrasive feel, similar to pumice powder, and has a low density as a result of its high porosity. The typical chemical composition of oven-dried diatomaceous earth is 80–90% silica, with 2–4% alumina, and 0.5–2% iron oxide.
Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pentoxide (P2O5). Marketed phosphate rock is enriched ("beneficiated") to at least 28%, often more than 30% P2O5. This occurs through washing, screening, de-liming, magnetic separation or flotation. By comparison, the average phosphorus content of sedimentary rocks is less than 0.2%.
An anticaking agent is an additive placed in powdered or granulated materials, such as table salt or confectioneries, to prevent the formation of lumps (caking) and for easing packaging, transport, flowability, and consumption. Caking mechanisms depend on the nature of the material. Crystalline solids often cake by formation of liquid bridge and subsequent fusion of microcrystals. Amorphous materials can cake by glass transitions and changes in viscosity. Polymorphic phase transitions can also induce caking.
Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. Organic refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.
Agrogeology is the study of the origins of minerals known as agrominerals and their applications. These minerals are of importance to farming and horticulture, especially with regard to soil fertility and fertilizer components. These minerals are usually essential plant nutrients. Agrogeology can also be defined as the application of geology to problems in agriculture, particularly in reference to soil productivity and health. This field is a combination of a few different fields, including geology, soil science, agronomy, and chemistry. The overall objective is to advance agricultural production by using geological resources to improve chemical and physical aspects of soil.
Agrominerals are minerals of importance to agriculture and horticulture industries for they can provide essential plant nutrients. Some agrominerals occur naturally or can be processed to be used as alternative fertilizers or soil amendments. The term agromineral was created in the 19th century and is now one of the leading research topics for sustainable agriculture. These geomaterials are used to replenish the nutrients and amend soils. Agrominerals started with small uses most often seen in hobbyist gardening but are moving to a much larger scale such as commercial farming operations that take up 100's acres of land. In this transition the focus changed to be more on ground nutrients, mainly on the three major plant nutrients nitrogen (N), phosphorus (P), and potassium (K). Two of the three elements are only being harvested from a geomaterial called potash. Alternative sources are being researched, due to potash finite supply and cost.
This glossary of geology is a list of definitions of terms and concepts relevant to geology, its sub-disciplines, and related fields. For other terms related to the Earth sciences, see Glossary of geography terms (disambiguation).
Phosphate rich organic manure is a type of fertilizer used as an alternative to diammonium phosphate and single super phosphate.
John D. Hamaker (1914–1994), was an American mechanical engineer, ecologist, agronomist and science writer in the fields of soil regeneration, rock dusting, mineral cycles, climate cycles and glaciology.
The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.
Remineralize the Earth (RTE) is a 501(c)(3) non-profit organization based in Northampton, Massachusetts, and founded in 1995 by Joanna Campe. The organization’s mission is to "promote the use of natural land and sea-based minerals to restore soils and forests, produce more nutritious food, and remove excess CO2 from the atmosphere”. RTE’s vision is to overcome desertification, increase food security by increasing the yields and nutritional values of food grown in healthy soils, and stabilize the climate by amending soils and forests across the globe with readily available and finely ground silicate rock dust and sea minerals.
Seventeen elements or nutrients are essential for plant growth and reproduction. They are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), nickel (Ni) and chlorine (Cl). Nutrients required for plants to complete their life cycle are considered essential nutrients. Nutrients that enhance the growth of plants but are not necessary to complete the plant's life cycle are considered non-essential, although some of them, such as silicon (Si), have been shown to improve nutrent availability, hence the use of stinging nettle and horsetail macerations in Biodynamic agriculture. With the exception of carbon, hydrogen and oxygen, which are supplied by carbon dioxide and water, and nitrogen, provided through nitrogen fixation, the nutrients derive originally from the mineral component of the soil. The Law of the Minimum expresses that when the available form of a nutrient is not in enough proportion in the soil solution, then other nutrients cannot be taken up at an optimum rate by a plant. A particular nutrient ratio of the soil solution is thus mandatory for optimizing plant growth, a value which might differ from nutrient ratios calculated from plant composition.
The potassium (K) cycle is the biogeochemical cycle that describes the movement of potassium throughout the Earth's lithosphere, biosphere, atmosphere, and hydrosphere.
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