Agrominerals

Last updated January 22, 2024

Agrominerals (also known as stone bread or petrol fertilizer) are minerals of importance to agriculture and horticulture industries for they can provide essential plant nutrients.^[1] Some agrominerals occur naturally or can be processed to be used as alternative fertilizers or soil amendments.^[1] 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).^[2] Two of the three elements are only being harvested from a geomaterial called potash.^[2] Alternative sources are being researched, due to potash finite supply and cost.^[3]

The process of using agrominerals starts with crushing rocks into a "rock powder," than using the powder to replenish soil nutrients.^[3] The process of replenishing mineral levels in a soil is called soil remineralization. While studying alternative ways to replenish ground nutrients, it has been found that agrominerals can also help mitigate other issues such climate change, water preservation and soil management.^[1]

History

The study of agrominerals is termed agrogeology, and agrogeologists are concerned with issues such as the replenishment of soil fertility in areas where agrominerals have been depleted by unsustainable farming methods. With current farming practice, the system is expected to have high crop production with low soil quality.^[1] Over time with this type of practice, ground nutrients have been depleted which has led to an increase in chemical fertilizer usage. Chemical fertilizers have been shown to have runoff and it can contaminate groundwaters and are not economically feasible for third world countries.^[1] One of the major sources for chemical fertilizers is potash ore.^[2] The other concern with the potash ore is the supply is finite and is running out, hence the increase in pricing.^[1] Potash is one of the major sources for potassium and phosphorus and one of the original agrominerals.^[2] Finding alternative sources for these agrominerals was a concept that was created to focus on soil remediation, to increase productivity in a low-cost manner.^[1]

At first agrominerals were used to help recreate soil conditions for exotic plants. These were simple practices that occur on a much smaller scale. These include using perlite to enhance the aeration of the soil, using pumice to control evaporation while one can use vermiculites and zeolites to store moisture.^[1] This soil modification was the start of the agromineral concept and has evolved into looking for alternative sources to obtain the three major nutrient elements.^[1] Remineralization has been the term created for implementing rock powders into soils as a source of nutrients.^[3] This process has been implemented into bigger operations and has found great success in places like Brazil, Germany, Norway, South Africa, Sri Lanka, and Uganda.^[3]

Sources

The original agromineral is potash, it is how chemical fertilizers get it potassium and phosphorus nutrients in the present day.^[2] Due to such a high demand, the ore is running in low supply which has increased its market value.^[1] The biggest limiting factor is potassium, despite being the fourth most abundant element in the Earth's crust it has only one major source that being potash.^[2] One of the popular alternative ideas to get away from the use of chemical fertilizer is spreading rock powders in the field as a source of nutrients.^[1] One of the major research areas involve looking feldspars and feldspathoids and determining which would more efficient to use.^[2] In one of the studies it showed that the feldspathoid nepheline had a much higher dissolution rate making it more efficient source of potassium than other rocks that are much more potassium-rich like granitic rocks.^[2]

There is a push to move away from chemical fertilizers since it has been connected to groundwater pollution. There has been a shift into looking at grinding rocks into a powder that can be incorporated into the ground as a new way to add nutrients to the soil.^[3] The idea behind rock powder originated from the idea that rock weather and is how nutrients were originally put in the soil; the soil is weathered rock.^[1] With this concept it has been determined that the rock source is very important because the rock can have unwanted elements that can be toxic for both the plant and the humans ingesting it.^[3] Research has been done on rocks such as basalt and dacite; each rock had their pros and cons.^[3] The success of the rock powder can be affected by crop cycle. For example, basalt was effective when it came to long-cycle crops, but short-cycle crops it was not as effective as chemical fertilizers.^[3] With some rock powders it can take anywhere between 1-5 years to show results.^[3] The biggest contributions to rocks being an effective rock powder comes down to mineralogy and chemical composition.^[1] Once rock sources that have the proper elements and effectiveness is found, the limitation to rock powders then becomes how it is ground. Grinding a mineral, like olivine, to a particle size that would be effective in the ground (1μm), takes about 1.5 gigajoules per ton of rock.^[3] Research will be needed to find more efficient ways to crush rock for rock-powders to be a sustainable solution for replenishing plant nutrients.

Remineralization

Agrominerals allow for nutrients to be added to the soil after a long history of crops depleting it.^[1] The agriculture industry is suffering from its high loss rate in arable layers in the soil and ground nutrients compared to the natural replenishment rate.^[3] Remineralization looks into the process of taking rock powders and incorporating it into the soil as a way to replenish the nutrients in the ground.^[1] With rock powder the plant absorbs only what it needs, and any unused minerals will remain crystalized until it is used.^[3] While chemical fertilizers use dissolvable salts to deliver the nutrients to the plant, whatever is not absorb will run off into the nearest groundwater.^[1]

Rocks have become a cheap by-product in many industries and so there is a potential for a massive supply of viables rocks for a cheap price.^[3] Remineralization using rock powder can provide up to 5 years’ worth of nutrients in a soil.^[3] When used in the combination with organic fertilizer, rock powder has proven to be just as effective as chemical fertilizer for a much smaller cost.^[3] It has even shown to have higher yields for long term crops.^[3] When using rock powder, the plants tended to look healthier, and it was found that the powder helps with holding moisture content.^[3] The effectiveness of the remineralization process is dependent on the mineralogy and chemistry of the rock powder, as well as the soil characteristics.^[1]

The challenge with rock powders is understanding the solubility rates of the rock powder.^[2] Rates are dependent on factors like organic matter, pH levels, secondary clay precipitation.^[3] This is a major area of research since their dissolution kinetics are not fully understood.^[1] One of the major challenges is recreating the field conditions in the lab, in many cases the solubility rates in the lab are 2-5 magnitudes higher than the ones in the field.^[1] It's important to fully understand what the mineralogy and chemical components of a rock. Volcanic rocks were thought to be a good source for rock powder but it was determined that it contains toxic elements as well.^[3] Research has been done into phosphate rocks, but these too have the issue of containing heavy and radioactive elements.^[1]

The use of rock powder in remineralization has the potential to help mitigate global warming.^[1] When nutrients from certain powders are absorbed, cations are released in the soil which reacts to with carbon dioxide to create carbonate minerals, which can serve as a carbon sink for the carbon cycle.^[1] With this discovery there has been a push to further look into remineralizations using rocks powders due to its sustainability potential both from a farming side and a global climate change side.^[1]

Related Research Articles

Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions. Terrestrial or aquatic plants may grow with their roots exposed to the nutritious liquid or the roots may be mechanically supported by an inert medium such as perlite, gravel, or other substrates.

<span class="mw-page-title-main">Potassium</span> Chemical element, symbol K and atomic number 19

Potassium is a chemical element; it has symbol K and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals, all of which have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge. In nature, potassium occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-colored flame. It is found dissolved in seawater, and occurs in many minerals such as orthoclase, a common constituent of granites and other igneous rocks.

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.

<span class="mw-page-title-main">Potash</span> Salt mixture

Potash includes various mined and manufactured salts that contain potassium in water-soluble form. The name derives from pot ash, plant ashes or wood ash soaked in water in a pot, the primary means of manufacturing potash before the Industrial Era. The word potassium is derived from potash.

Soil test may refer to one or more of a wide variety of soil analysis conducted for one of several possible reasons. Possibly the most widely conducted soil tests are those done to estimate the plant-available concentrations of plant nutrients, in order to determine fertilizer recommendations in agriculture. Other soil tests may be done for engineering (geotechnical), geochemical or ecological investigations.

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.

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.

Agricultural lime, also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate. Additional chemicals vary depending on the mineral source and may include calcium oxide. Unlike the types of lime called quicklime and slaked lime, powdered limestone does not require lime burning in a lime kiln; it only requires milling. All of these types of lime are sometimes used as soil conditioners, with a common theme of providing a base to correct acidity, but lime for farm fields today is often crushed limestone. Historically, liming of farm fields in centuries past was often done with burnt lime; the difference is at least partially explained by the fact that affordable mass-production-scale fine milling of stone and ore relies on technologies developed since the mid-19th century.

Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. It also refers to the soil's ability to supply plant/crop nutrients in the right quantities and qualities over a sustained period of time. A fertile soil has the following properties:

<span class="mw-page-title-main">Soil conservation</span> Preservation of soil nutrients

Soil conservation is the prevention of loss of the topmost layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.

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. The organic-mess 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.

Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons. Acidification also occurs when base cations such as calcium, magnesium, potassium and sodium are leached from the soil.

Fertigation is the injection of fertilizers, used for soil amendments, water amendments and other water-soluble products into an irrigation system.

In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss. Leaching may also refer to the practice of applying a small amount of excess irrigation where the water has a high salt content to avoid salts from building up in the soil. Where this is practiced, drainage must also usually be employed, to carry away the excess water.

A biofertilizer is a substance which contains living micro-organisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances. The micro-organisms in biofertilizers restore the soil's natural nutrient cycle and build soil organic matter. Through the use of biofertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil. Biofertilizers can be expected to reduce the use of synthetic fertilizers and pesticides, but they are not yet able to replace their use. Since they play several roles, a preferred scientific term for such beneficial bacteria is "plant-growth promoting rhizobacteria" (PGPR).

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.

Haifa Group is a private international corporation which primarily manufactures Potassium Nitrate for agriculture and industry, specialty plant nutrients and food phosphates. Haifa Group (Haifa) is the world pioneer in developing and supplying Potassium Nitrate and Specialty Plant Nutrients for advanced agriculture in various climates, weather, and soil conditions. Haifa also manufactures Controlled Release Fertilizers (CRF) for agriculture, horticulture, ornamentals, and turf. Many of Haifa's fertilizers can be used as a fertilizer solution that is applied through drip irrigation. This latter application is the principal driver of demand today, now that more countries are turning to controlled irrigation systems that make more efficient use of water.

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.

References

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Zhang, Guanru; Kang, Jinting; Wang, Tianxing; Zhu, Chen (2017). "Review and outlook for agromineral research in agriculture and climate mitigation". Soil Research. 56 (2): 113–122. doi:10.1071/SR17157. ISSN 1838-6768.
1 2 3 4 5 6 7 8 9 Manning, David A. C. (2010). "Mineral sources of potassium for plant nutrition. A review". Agronomy for Sustainable Development. 30 (2): 281–294. doi:10.1051/agro/2009023. ISSN 1773-0155. S2CID 25963588.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Ramos, Claudete Gindri; Hower, James C.; Blanco, Erika; Oliveira, Marcos Leandro Silva; Theodoro, Suzi Huff (2021). "Possibilities of using silicate rock powder: An overview". Geoscience Frontiers. 13: 101185. doi: 10.1016/j.gsf.2021.101185 . hdl: 11323/8357 . ISSN 1674-9871. S2CID 233699192.

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[:0-1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Zhang, Guanru; Kang, Jinting; Wang, Tianxing; Zhu, Chen (2017). "Review and outlook for agromineral research in agriculture and climate mitigation". Soil Research. 56 (2): 113–122. doi:10.1071/SR17157. ISSN 1838-6768.

[:1-2] 1 2 3 4 5 6 7 8 9 Manning, David A. C. (2010). "Mineral sources of potassium for plant nutrition. A review". Agronomy for Sustainable Development. 30 (2): 281–294. doi:10.1051/agro/2009023. ISSN 1773-0155. S2CID 25963588.

[:2-3] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Ramos, Claudete Gindri; Hower, James C.; Blanco, Erika; Oliveira, Marcos Leandro Silva; Theodoro, Suzi Huff (2021). "Possibilities of using silicate rock powder: An overview". Geoscience Frontiers. 13: 101185. doi: 10.1016/j.gsf.2021.101185 . hdl: 11323/8357 . ISSN 1674-9871. S2CID 233699192.

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