Tag Archives: soil

Researchers develop a method to 3D print buildings from any local soil

New research is making it possible to print buildings from the ground up — quite literally.

An experimental structure created with the method.
Image credits Aayushi Bajpayee.

Most construction materials today require intense processing to create. This makes them both relatively expensive, and quite damaging from an environmental point of view. But new research could make buildings dirt-cheap, by allowing their construction from actual dirt.

The building process involves a 3D printer creating the load-bearing structure out of soil (this is the part of the building that keeps it up), with the final touches to be completed from other locally-available material.

Ashes to ashes, dirt to houses

“The environmental impact of the construction industry is an issue of growing concern,” says Sarbajit Banerjee, Ph.D., the project’s principal investigator.

“Some researchers have turned to additive manufacturing, or building structures layer by layer, which is often done with a 3D printer. That advance has begun to transform this sector in terms of reducing waste, but the materials used in the process need to be sustainable as well.”

Concrete is the most widely used construction material today, but it has a high environmental footprint and requires a lot of energy and specialized installations to produce. Concrete manufacturing is responsible for around 7% of global CO2 emissions, the team notes.

Using any locally-available soils for construction would thus help ease the burden both on the environment and our savings accounts. This method has been employed for a huge part of human history, but mixing in modern technology with this ancient method can help take it to new heights.

“Our thought was to turn the clock back and find a way to adapt materials from our own backyards as a potential replacement for concrete,” says Aayushi Bajpayee, a graduate student in Banerjee’s lab at Texas A&M University.

The process uses soil as the ‘ink’ in a 3D printer (called ‘additive manufacturing’) to create the skeleton of a building. Banerjee and Bajpayee also say that the process could one day be used to create settlements on the moon or even Mars.

The team started working from soil samples collected from one of their backyards and developed a binder that would hold it together but still keep it flowy enough to go through the printer. Soils are far from uniform, and their composition can vary wildly from place to place. Because of this, the binder (or ‘additive’) is described as a chemical ‘toolkit’ designed to interact with soils of every chemistry.

The team first tested their approach by building small test structures in the shape of cubes measuring two inches on each side. Then, they tested whether the material can adequately bear weight without collapsing — for this step, they “zippered” the soil mixture into microscopic layers on the structure’s surface to prevent it from absorbing water and expanding. Using this method, the material could bear twice the load of an un-zippered one, and was deemed resilient enough. The team is still working on improving the strength of the mixture, planning to get it as close to concrete as possible.

The researchers will present their results today at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo.

Wetter, warmer soils will intensify climate change

Climate change is poised to make tropical ecosystems wetter — which will make them release more carbon dioxide, according to a new paper.

Image via Pixabay.

The study focused on an analysis of ancient tropical soils from the submarine delta of the Ganges and Brahmaputra rivers. Throughout history, the data reveals, these soils have emitted higher levels of CO2 gas during warmer and wetter periods. The team writes that the same mechanism can amplify the effect of climate change as tropical soils today will release more CO2 into the atmosphere on top of (and due to) human emissions.

A study in the May 6th issue of Nature indicates the increase in rainfall forecast by global climate models is likely to hasten the release of carbon dioxide from tropical soils, further intensifying the climate crisis by adding to human emissions of this greenhouse gas into Earth’s atmosphere.

Worse with water

“We found that shifts toward a warmer and wetter climate in the drainage basin of the Ganges and Brahmaputra rivers over the last 18,000 years enhanced rates of soil respiration and decreased stocks of soil carbon,” says Dr. Christopher Hein of William & Mary’s Virginia Institute of Marine Science, lead author of the paper.

“This has direct implications for Earth’s future, as climate change is likely to increase rainfall in tropical regions, further accelerating respiration of soil carbon, and adding even more CO2 to the atmosphere than that directly added by humans.”

Soil respiration represents the CO2 gas released by microbes into the atmosphere as they munch on and decompose organic material at or just below the ground surface such as leaves, roots, and dead organic matter. It’s not very different, actually, from the way humans and other animals generate CO2 from cellular processes that they then breathe out.

Plant roots also contribute to soil respiration during the night when plants can’t photosynthesize, and so burn off some of the carbohydrates (sugars) they produced during the day for energy.

The team analyzed three cores collected from the ocean floor at the mouth of the Ganges and Brahmaputra rivers in Bangladesh — which form the world’s largest delta and abyssal fan with sediments eroded from the Himalayas. These cores allowed the team to track environmental changes in the region over the last 18,000 years. Their data showed that there is a strong link between soil age and runoff rates.

Younger soils, which formed during wetter epochs, showed more rapid respiration rates, while older ones — which formed in cooler, drier times — showed less respiration and held higher quantities of carbon for longer periods of time. The wetter times correlate with periods of the Indian summer monsoon, the primary source of precipitation across India, the Himalayas, and south-central Asia, was stronger. The team confirmed this link by analyzing other paleoclimatic evidence in geologic formations and fossil phytoplankton.

“Small changes in the amount of carbon stored in soils can play an outsized role in modulating atmospheric CO2 concentrations and, therefore, global climate, as soils are a primary global reservoir of this element,” Hein explains.

The team notes that soils hold an estimated 3,500 billion tons of carbon or around four times as much as the quantity of this element in the atmosphere.

The feedback process seen by the team here — where atmospheric CO2 drives global warming which increases the release of CO2 — is only one piece of a larger image. Similar findings on permafrost soils of the Arctic circle have been made in the past. There, widespread thawing is allowing for more extensive microbial activity and is responsible for an estimated 0.6 billion tons of carbon emissions to the atmosphere each year.

The paper “Millennial-scale hydroclimate control of tropical soil carbon storage,” has been published in the journal Nature.

Scientists uncover how soil closes deadly wounds

Credit: Pixabay.

A team of researchers at the University of British Columbia has shown for the first time that soil silicates promote blood clotting, rapidly closing potentially deadly wounds.

“Soil is not simply our matrix for growing food and for building materials. Here we discovered that soil can actually help control bleeding after injury by triggering clotting,” Dr. Christian Kastrup, associate professor of biochemistry and molecular biology at UBC and the study’s senior author, said in a statement.

When soil interacts with blood, it triggers the activation of a protein known as coagulation Factor XII. The protein enables a chain reaction that eventually seals the wound and limits potentially fatal blood loss.

Death from blood loss can occur in as little as five minutes following trauma. A study performed by researchers at the Uniformed Services University of the Health Sciences in Bethesda, Maryland estimated that about 500 people in the United States die every year from external hemorrhage.

“Excessive bleeding is responsible for up to 40 percent of mortality in trauma patients. In extreme cases and in remote areas without access to healthcare and wound sealing products, like sponges and sealants, sterilized soil could potentially be used to stem deadly bleeding following injuries,” says Dr. Kastrup.

Don’t try this at home

This doesn’t mean that you can just throw a handful of dirt on a bleeding wound. Unsterilized soil presents a great risk of infection, which could make matters a lot worse. Tetanus and soil fungus infections are well known to happen when a wound is filled with dirt. It’s one of the reasons a doctor will first clean a wound before applying medicine and a bandage.

However, the findings could have important implications for how wounds are treated in a hospital setting or even on the battlefield. Doctors could use sterilized dirt to manage bleeding and even learn new things about how infections occur after trauma.

Particularly, sterilized dirt could prove very effective in remote environments with limited resources and medical supplies. Poor and remote regions of the globe come to mind, but the researchers believe that sterilized dirt could prove indispensable in managing wounds occurring on other worlds too, such as injuries sustained by astronauts on the moon or Mars.

“This finding demonstrates how terrestrial mammals, ranging from mice to humans, evolved to naturally use silicates as a specific signal to Factor XII to trigger blood clotting,” says Lih Jiin Juang, the study’s first author and UBC PhD student in the department of biochemistry and molecular biology. “These results will have a profound impact on the way we view our relationship with our environment.”

The findings appeared in the journal Blood Advances.

New species of soil bacteria can break down soil pollutants

Researchers at Cornell University discovered a new species of bacteria that can break down organic contaminants in the soil.

Image via Pixabay.

The new species was named Paraburkholderia madseniana in honor of the late Gene Madsen, the microbiology professor who started the research. The species is particularly adept at breaking down aromatic compounds (ring-like molecules of carbon), a large class of organic compounds that includes several types of pollutants.

Cleaning the soiled

“Microbes have been here since life began, almost 4 billion years. They created the system that we live in, and they sustain it,” said Dan Buckley, professor of microbial ecology at Cornell’s School of Integrative Plant Science. “We may not see them, but they’re running the show.”

Professor Madsen discovered the bacteria in soil samples from the Turkey Hill road meadow, an experimental forest stewarded by the Cornell Botanic Gardens. However, he passed away in 2017 before he could prove the bacteria’s abilities, which this study reports on.

The species belongs to the genus Paraburkholderia, which are known for their ability to decompose aromatic compounds. Some species in this genus are also known to form symbiotic relationships with plants, creating nodules around their roots and supplying nitrogen.

Madsen, however, focused his work on biodegradation — the process by which bacteria break organic matter down to extract energy, — with a particular eye towards organic pollutants called polycyclic aromatic hydrocarbons (PAHs). His work helped further our understanding of how natural tools can be applied to clear waste areas in which soils can’t be easily de-contaminated or removed.

The first step of the research was to sequence the bacteria’s RNA, which showed it to be a new species. Subsequent observation showed that madseniana can break down aromatic hydrocarbons; this ability, the team explains, was likely evolved as it allows madseniana to break down lignin, a major structural component of wood and plant tissues. Luckily for us, this also allows it to attack a wide range of organic pollutants generated through the use of fossil fuels.

“We know remarkably little about how soil bacteria operate,” Buckley said. “Soils, every year, process about seven times more carbon than all of the human emissions from cars, power plants and heating units, all over the world, just in their natural work of decomposing plant material.”

“Because it’s such a large amount of carbon going through the soil, small changes in how we manage soil could make a big impact on climate change.”

In the future, the team plans to investigate the relationship between madseniana and forest trees. Their findings so far suggest that trees trade carbon with colonies of the bacteria around their roots, which break down organic matter and return vital nutrients such as phosphorous and nitrogen.

The paper “Paraburkholderia madseniana sp. nov., a phenolic acid-degrading bacterium isolated from acidic forest soil” has been published in the International Journal of Systematic and Evolutionary Microbiology.

Cutting down trees and planting new ones is wrecking the soil

It’s always a good idea to plant new trees after you cut some old ones. But that’s not exactly sustainable, a new analysis shows.

Image in public domain.

Forests still cover about 30% of the world’s land area, but their coverage are decreasing fast. Logging has always been an issue in modern times, with 1.3 million square kilometers of forest being lost between 1990 and 2016. Since humans have started cutting forests, 46% of trees have been felled, according to a 2015 study in the journal Nature. After a few encouraging signs, deforestation is once again on the rise.

Of course, forests have a natural replenishment rate, and humans also plant new tree areas. These efforts have put a dent in overall deforestation figures, although the net effect still heavily leans towards deforestation.

But even cutting trees and planting an equal amount is problematic, a new study suggests. Trees of recovering tropical forests were found to be different from those of old-growth forests. They had tougher leaves, with lower concentrations of the nutrients phosphorus and nitrogen — both essential for plant and tree growth. This is because constantly cutting trees and planting new ones depletes the soils of crucial nutrients, a new study concludes.

Essentially, multiple cycles of logging and replanting irreversibly remove phosphorus from the forest system — pushing the forest to its very limit.

“Old-growth tropical forests that have been the same for millions of years are now changing irreversibly due to repeated logging,” said Dr Tom Swinfield, a plant scientist at the University of Cambridge Conservation Research Institute, and first author of the paper published in the journal Global Change Biology.

Nutrients like phosphorus come from rocks, which are slowly incorporated into soil, from where they are absorbed by roots. When a tree is cut, these nutrients are lost. Swinfield and colleagues calculated that as much as 30% of the phosphorus in the soil is removed by repeated logging.

In order to do this, they used LIDAR measurements to create high-definition images of forests in north-eastern Borneo. This method uses high-precision laser scanners to take numerous measurements across the entire light spectrum to create a very detailed, 3D image of the forests. They then combined this data with nutrient measurements from 700 individual trees in the same forest — this allowed them to map the concentrations of nutrients in tree leaves over natural growth areas and areas with repeated logging.

The researchers found that differences from old-growth forest become more pronounced as logged forests grow larger over time, suggesting exacerbated phosphorus limitation as forests recover.

Each consecutive logging harvest reduces the levels of nutrients in the soil, the team adds. So far, trees seem to be coping, but they are being stressed more and more.

“We see that as the logged forests start recovering, they’re actually diverging from the old growth forests in terms of their leaf chemistry and possibly also species composition, as the amount of available nutrients goes down,” said Swinfield. “At the moment the trees can cope, but the fact that they’re changing indicates phosphorus levels in the soil are dropping. This could affect the speed at which forests recover from future disturbances.”

This matter has been severely understudied, the researchers also emphasize. Globally, we tend to think of forests as a zero-sum game: if we plant as much as we cut, then everything’s alright. But that’s not really the case.

Soils are often ignored in the conversation, and this can have devastating consequences for forest conservation. Also, it’s not just that the trees are there — not all trees are alike, and natural-growth, stress-free trees provide much better environmental services.

Lastly, while the study focused on Borneo, it is very likely that this issue affects forests worldwide.

“Phosphorus limitation is a really serious global issue: it’s one of the areas where humans are using a vital resource beyond sustainable levels,” concludes Professor David Coomes, Director of the University of Cambridge Conservation Research Institute, who led the project.

Journal Reference: Swinfield, T. et al: ‘Imaging spectroscopy reveals the effects of topography and logging on the leaf chemistry of tropical forest canopy trees.’ Global Change Biology, Dec 2019. DOI: 10.1111/GCB.14903

Lunar dirt can be broken down into oxygen and metals

New research from the University of Glasgow is working out how to squeeze metal and oxygen from dry rock; dry moon rocks that is.

Image credits Beth Lomax, University of Glasgow.

Samples of regolith (dirt) retrieved from the Moon revealed that the material is made up of between 40% to 45% oxygen by weight. Essentially, this vital (for us) gas is the single most abundant element in the lunar soil. A group of researchers plans to draw the oxygen out of the dirt, in order to give astronauts and colonists a reliable and plentiful source of breathable air and metals.

Rise from the dirt

“This oxygen is an extremely valuable resource, but it is chemically bound in the material as oxides in the form of minerals or glass, and is therefore unavailable for immediate use,” explains researcher Beth Lomax of the University of Glasgow, whose Ph.D. work is being supported through the European Space Agency’s (ESA) Networking and Partnering Initiative.

The approach involves the use of molten salt electrolysis to pry apart the Oxygen and metallic atoms in regolith. The team reports that this is the first “direct powder-to-powder processing of solid lunar regolith simulant” that can extract all the oxygen in such a sample. Alternative methods, they add, either achieve much lower yields or require extreme temperatures (in excess of 1600°C) to work.

The team placed powdered regolith in a mesh-lined basket, mixing in molten calcium chloride salt as an electrolyte. Then they baked everything up to 950°C. While the regolith is still solid at this temperature, the team explains that pushing current through it causes the oxygen atoms to migrate across the molten salt and build-up at the anode.

The technique takes around 50 hours to pull 96% of the oxygen from a sample, but around 75% of the total is extracted in the first 15 hours.

“This research provides a proof-of-concept that we can extract and utilise all the oxygen from lunar regolith, leaving a potentially useful metallic by-product,” adds Lomax.

“This work is based on the FCC process — from the initials of its Cambridge-based inventors — which has been scaled up by a UK company called Metalysis for commercial metal and alloy production.”

Going forward, the team plans to continue cooperating with Metalysis and ESA to ready the process for a lunar context. The process would give lunar settlers access to oxygen for fuel and life support, and raw material (metals) for on-site manufacturing. Exactly what metals they would obtain, the team says, would depend on where on the Moon they land.

Furthermore, the same approach could likely work on Mars as well, materials engineer Advenit Makaya told Phys. The findings also tie in nicely with previous research that developed an approach to extract water out of lunar regolith. Future colonists, it seems, will have ample resources at their disposal.

The paper “Proving the viability of an electrochemical process for the simultaneous extraction of oxygen and production of metal alloys from lunar regolith” has been published in the journal Planetary and Space Science.


Researchers, at long last, develop effective tool to study soil-borne microbes

Novel research is allowing us to see what different microbes in the soil are up to.


Image via Pixabay.

Researchers from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) report being the first to successfully isolate active microbes from a soil sample. These germs underpin life on Earth today, so the research has the potential to branch out into many other fields including ecosystem science, environmental rehabilitation, and agriculture.

Soil searching

Soils are probably the most diverse microbial communities on the planet,” said Estelle Couradeau, first author of the study. “In every gram of soil, there are billions of cells from tens of thousands of species that, all together, perform important Earth nutrient cycles. They are the backbone of terrestrial ecosystems, and healthy soil microbiomes are key to sustainable agriculture.”

“We now have the tools to see who these species are, but we don’t yet know how they do what they do. This proof-of-concept study shows that BONCAT is an effective tool that we could use to link active microbes to environmental processes.”

For the past two years, Couradeau and her co-authors have been collaborating with other researchers in a Berkeley Lab-led scientific focus area called ENIGMA (Ecosystems and Networks Integrated with Genes and Molecular Assemblies) to better understand soil microbiomes. ENIGMA’s projects are of great interest to researchers in the field of biology, energy, and Earth sciences.

Soil microbes are hard to study because they won’t grow in lab cultures, and because they come in an extremely wide palette in natural habitats. Many of these microbes as much as 95% at a time, according to the team can also lie inactive at any given time, further complicating efforts to tie their activity to observed effects. Because of this, researchers usually study such microbes by collecting samples and then sequencing bulk DNA to determine which strains are present therein. However, most of the commonly used techniques can’t differentiate active microbes from those that are dormant or from free-floating bits of DNA found in soil and sediment.

Sleeper cells

“There are many barriers to measuring microbial activities and interactions,” said Trent Northen, lead author and director of biotechnology for ENIGMA

Enter BONCAT (Bioorthogonal Non-Canonical Amino Acid Tagging), a microbial sorting tool that allows researchers to tell apart active vs inactive microbes in a sample. Northen’s team is the first one to successfully use this technique on a sample of soil, and they hope the research will help us understand how soil microbiomes affect large-scale environmental events. BONCAT was developed by Caltech geneticists in 2006 as a way to isolate newly made proteins in cells, and was later adapted into a tool that could identify active, symbiotic clusters of dozens to hundreds of microbes within ocean sediment. Further refinement of this method led to the development of BONCAT Fluorescent Activated Cell Sorting (BONCAT+FACS), which is able to detect individual active microbes.

With BONCAT+FACS, researchers sort through single-celled organisms using a fluorescent tagging molecule, which binds to a modified version of methionine (an amino acid). A fluid solution containing the modified methionine is introduced to a sample of microbes, and those that are active — i.e. that are synthesizing proteins — will incorporate the modified methionine into their structures. The process is much more streamlined and reliable than previous microbial identification methods, and only takes a few hours to perform (which means it can tag active cells even when they are not replicating).

The team spent three months tweaking and optimizing the technique, which resulted in a protocol that can smoothly and reliably identify active microbes in a sample — “most importantly”, according to a press release accompanying the study, the technique “gives very reproducible results”.

“BONCAT+FACS is a powerful tool that provides a more refined method to determine which microbes are active in a community at any particular time,” said  Rex Malmstrom, co-author of the study who previously worked on refining BONCAT for marine use.

“It also opens the door for us to experiment, to assess which cells are active under condition A and which cells become active or inactive when switched to condition B.”

“With BONCAT, we will be able to get immediate snapshots of how microbiomes react to both normal habitat fluctuations and extreme climate events—such as drought and flood—that are becoming more and more frequent,” said Northen.

BONCAT+FACS will be available through the user programs set up by the Department of Energy’s Joint Genome Institute (JGI), the authors write. They hope to promote research in other lines of study, among which they cite assessing antibiotic susceptibility in unculturable microbes and investigating the completely unknown roles of Candidatus Dormibacteraeota, a phylum of soil bacteria, found across the world, that appear to remain dormant most of the time. The technique will also help fill in the gaps of our understanding of environmental functions and point the way for new research into drought-resistance in crops, the sustainable production of fuel and other bioproducts, environmental rehabilitation, and many others.

The paper “Probing the active fraction of soil microbiomes using BONCAT-FACS” has been published in the journal Nature.

Plant soil.

What is soil? Here’s the inside scoop

Ground beneath your feet — all planets have it (yes even gas giants). But the one on our Earth is a little different from those in other places. So, what exactly is soil, and what makes ours stand out?

Plant soil.

Image via Pixabay.

Soils are actually very complex things. They’re a mix of solid material — both organic and inorganic — with fluids such as water and air, with a helping of living organisms thrown in to tie everything together. It’s a very dynamic material, one that responds to factors such as climate, terrain, biology, and human activity to name a few. It’s also continuously developing. Depending on where on Earth you look, and when, soils take on unique properties. It’s so complex, in fact, that soils are treated as ecosystems unto themselves.

However, life as we know it would be impossible without soil. So, everybody, grab your spades and let’s take a look at what exactly soil is.

The most bare-bones definition of soil is that it is a mixture of sand, clay, silt, and humus (not the tasty spread). In more geologically-savvy talk, soil is the unconsolidated mineral and/or organic material that forms on the immediate surface of the Earth. According to the Soil Science Society of America Glossary of Soil Science Terms, soil is also “subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time.” In other words, soils represent a mixture of geology and biology, and they are, quite literally, the substrate that fosters life on dry land.

The inorganic parts



Sand is not readily carried by water.
Image credits Andrew Martin.

The ‘geology’ part includes the inorganic elements of soil — mainly ground-up, weathered rocks and minerals. Weathering are the mechanical or chemical processes through which rocks are broken down into smaller pieces. These rocks and minerals are referred to as the soil’s “parent material“. This inorganic fraction represents around 90% by volume of all the solid material in the mix.

Soil texture is mainly produced by the ratios of different types of inorganic material in the soil. We generally classify these by the size of their particles. The three main types are sand, silt, and clay.

Sand is the coarsest of the three, with particles ranging in diameter from 0.0625 mm to 2 mm. Soils that contain more than 85% sand-sized particles by weight are called sand. Its exact composition varies from place to place, but generally, sand is made up of silica (quartz).

Particles in sand are pretty loose and coarse which creates a lot of open spaces for water to flow through. This makes sand very good at draining and filtering water. Its lack of organic material and inability to hold water, however, makes it a very poor environment for plants to grow in.

Silty water.

Silt is easily mixed with water because of how light its particles are, and can be carried over great distances.
Image credits Andrew Martin.

Silt is an intermediate texture, with particles ranging between 0.0039 mm and 0.0625 mm in diameter. To give you a rough idea, dry silt feels like coarse flour in your hands. Add water to it, and it would feel smooth, almost silky to the touch, without being sticky. Silt is much better than sand at holding in water. Due to its smaller-sized particles, it can be transported over long distances by wind (forming loess) or rivers. It is composed mainly of quartz and feldspar.

Silt an important component for fertile soils. Because of the size of its particles, it’s good at holding water for plants to absorb through their roots, but also creates enough open spaces for air pockets to form (more on that later). Smaller particles also mean they can be circulated around an environment to provide fresh minerals for plants. The Nile River, for example, brings huge amounts of fresh silt, rich in organic material, to bear on its banks every time it floods; this has single handedly fed Ancient Egypt’s ascent in the middle of an inhospitable desert. It had such a central role to play in the Egyptians’ life that they adopted the black silt on the Nile’s banks as a symbol of rebirth.


Clay can absorb a lot of water — and all that water increases its volume. Clay contracts and breaks apart when it dries and sheds those water molecules.

Clay is the finest type of material on the list. Its texture feels like that of eye shadow. While the exact point at which a particle is no longer considered silt varies depending on which discipline you’re asking, geologists usually consider particles under 2 micrometers to be clay. It’s usually made up of metallic oxides, which make clay quite colorful. These oxides are why clay-fired bricks are red, but clay can come in a wide range of colors.

Clays are made of wide, flat particles — which means that they have large surface areas compared to the other inorganic fractions. This makes them more chemically active than silt or sand and thus, better able to hold nutrients onto their surfaces. As such, clays can help make very fertile soils. Too much clay, however, can dry plants out — clay particles are good at capturing water but not very good at letting it go.

Overall, the inorganic components of soil mainly include silica, with iron and aluminum oxides. They mainly create soil’s texture and structure. Overall, it isn’t of much value to plants, although fractions like clay can transport nutrients.

The organic parts

Apple soil.

Image credits Annette Meyer.

Geology alone isn’t enough to produce soil. Mars, too, has a lot of ground-up, weathered rocks and minerals about its surface. So does the moon — but that’s just barren dirt. The components that set ‘soil’ apart from ‘dirt’, the bits that give it its unique pizzaz, are biological. Soil is pretty dense in organic material, which makes up around 10% of the volume of its solid components. The two main types of organic matter in soil are the living and the non-living fractions.

The latter improves soil’s ability to hold water, improves its nutritive value, and helps form stable aggregates (i.e. it ties everything together). It mostly originates from the microbial decomposition of animal or plant material (such as leaves, roots, soft tissues, or feces). This breakdown process recirculates nutrients through the soil to feed plants. Exactly how fast this material breaks down depends on how homey the soil is for bacteria. Higher decomposition rates occur in warm, moist conditions with good aeration, a favorable ratio of nutrients, with a pH (soil acidity) near neutral, and without pollutants or toxins.

Organic matter content in soil depends on how much of it is added versus how much of it is broken down over a given unit of time. Bacteria first munch on the juicier bits, such as sugars, starch, and certain proteins. More resistant compounds — such as the structural components in cell walls — are decomposed relatively slowly. These compounds, such as lignin and tannin, impart a dark color to soils containing a significant organic matter content. In general, the darker the soil, the more organic material it contains — so the better it is for growing plants.


Compost is just organic material slowly breaking down into soil.
Image credits Manfred Antranias Zimmer.

Living organic matter includes the aforementioned bacteria, earthworms, and everything in between. Fungi, actinomycetes, algae (yes, there is algae in soil), and protozoa also make an appearance. These organisms all work together to make soil the complex ecosystem it is, but they can both support and hinder plant growth. They can help plants by decomposing organic matter, fixing nitrogen (which plants can’t do themselves), and by improving soil quality through aggregation, aeration, and drainage. On the other end of the spectrum, they can compete with plants for nutrients or munch on their roots.

Soil structure

Soil profile.

Its a layered dirt cake!
Image credits Colin Smith.

Soils have complex structures to go along with their complex makeup. Dig down through some and you’ll see it’s made of layers, which are also called ‘horizons’. Taken together, all of these horizons form a soil’s profile. As a rule of thumb, almost all soils have three major horizons, and most also have an organic horizon. In order, a soil’s profile can include:

  • An organic/humus horizon. This material is mostly made up of organic matter in various stages of decay. If you’ve ever walked through a thick forest in spring, you may have noticed that there’s a brown, wet, mushy layer of something between the fallen leaves of last year and the ground proper. That’s plant matter that is rapidly being turned into soil and is part of this organic horizon. This layer shows great variation between soils: it’s thin in some, thick in others, and completely absent in some cases.
  • Topsoil. This horizon is mostly made up of minerals from the soil’s parent material mixed in with a healthy heaping of organic matter. It’s a very cozy place, and most plants and animals that live in soil call this layer home.
  • The eluviated horizon. This is a blanket of gravel, sand, and silt particles of quartz or other particularly hardy materials left over after the clay, organic matter, and more soluble minerals have been washed away by water draining through the soil. It has to be noted that water does this to the above horizons as well, but those tend to be replenished through organic decomposition. The eluviated horizon isn’t seen in most soils but is quite often found in older soils and forest soils.
  • The subsoil. This part is packed with minerals and nutrients washed down from the above layers that get stuck here like coffee grounds onto filter paper.
  • Parent material. The inorganic ‘foundation’ from which the soil developed.
  • The bedrock. A solid mass of solid rocks (usually granite, basalt, quartzite, limestone, or sandstone). If the bedrock is close enough to the surface to weather, it can serve as the parent material for the above soil. But, make no mistake — this is rock. This bit isn’t considered soil.

A lot of this column, ideally, is empty air. Fertile, medium-grain soils can reach up to 50% porosity, and all this empty space is crucial for its health. The pores allow air and water to pool and (ideally) circulate through the soil, keeping both its flora and fauna alive.

Pore size (which is dictated by particle size) is important, too, as is the distribution of these pores. If a pore is too small, it traps water too tightly for plants to absorb. That’s why soils with a large clay content aren’t very good for agriculture. We till the land as a way to break it up and temporarily increase its porosity and permeability.

Pores that are too large just let water woosh right through, as we discussed earlier, which is just as bad for plants. Large pores that communicate (i.e. that are connected) with one another allow water and air to move freely through the soil, carrying nutrients around. However, smaller pores are better if you’re dealing with drought — they store water better.

As far as flora is concerned, pores can keep different populations of bacteria separate from one another. This is actually pretty good news since it keeps the strains from competing with one another directly. As such, soil porosity allows for multiple organisms that occupy the same ecological niche to coexist, which improves its resilience to shocks such as pollution or climate change.

It’s easy to take the soil under our feet for granted — after all, it’s just dirt in our soles. But hopefully, I’ve helped you see a glimpse of the living, breathing ecosystem that underpins all of the life on dry land, and most of the life on Earth. So the next time you visit the park, spare a moment to think of all the hard work that’s going on beneath your shoes — we wouldn’t be here without it.

New bacteria strain.

Irish dirt might cure the world of (most) multi-drug-resistant bacteria

Irish soil might win us the fight against drug-resistant superbugs. Literally!

New bacteria strain.

Growth of the newly discovered Streptomyces sp. myrophorea. Although superficially resembling fungi, Streptomyces are true bacteria and are the source of two-thirds of the various frontline antibiotics used in medicine.
Image credits G Quinn / Swansea University

An international team of researchers based at the Swansea University Medical School, UK, reports finding a new strain of bacteria that can murder pathogens that our antibiotics increasingly cannot. The bacteria has been found in soil samples recovered from an area of Fermanagh, Northern Ireland.

Bad bugs get grounded

“This new strain of bacteria is effective against 4 of the top 6 pathogens that are resistant to antibiotics, including MRSA. Our discovery is an important step forward in the fight against antibiotic resistance,” says Professor Paul Dyson of Swansea University Medical School, paper co-author.

The finding is far from inconsequential. The World Health Organisation (WHO) describes rising antibiotic resistance as “one of the biggest threats to global health, food security, and development today”. Further research also estimated that antibiotic-resistant ‘superbugs’ could lead up to 1.3 million deaths in Europe alone by 2050.

The team named their discovery Streptomyces sp. myrophorea. It was discovered in the Boho Highlands, County Fermanagh, Northern Ireland, hiding in the soil. The researchers investigated the soils there as Dr. Gerry Quinn, a previous resident of the area, became curious to investigate local healing traditions.

Those traditions called for a small amount of soil to be wrapped up in cotton cloth and applied to cure ailments varying from toothaches to throat or neck infections. The team notes that the area has been inhabited for at least 4,000 years — first by Neolithic tribes and later druidic tribes — who may have started this tradition.

Lab tests later revealed the presence of the strain in local soils, and clued the team in on their impressive antibacterial properties. This bacteria inhibited the growth of four of the top six multi-resistant pathogens (those listed by the WHO as being responsible for healthcare-associated infections): Vancomycin-resistant Enterococcus faecium (VRE), methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumonia, and Carbenepenem-resistant Acinetobacter baumanii. It was also successful in inhibiting both gram positive and gram negative bacteria, which differ in the structure of their cell wall. Gram-negative bacteria are, generally speaking, more resistant to antibiotics.

It is not yet clear exactly how the bacteria do this, but the team is hard at work finding out.

New bacteria strain.

Zone of inhibition (light brown) produced by Streptomyces sp myrophorea (brown spot) on a lawn of MRSA.
Image credits G Quinn / Swansea University.

The active compounds secreted by Streptomyces sp.myrophorea could help create a new class of treatment against multi-drug resistant bacteria, the study reports. These pathogens are one of the most pressing threats to public health currently, as doctors are often left powerless to treat them. They’re especially dangerous in hospitals, where the large density of patients (often with weakened or compromised immune systems) means easy pickings for such pathogens.

“Our results show that folklore and traditional medicines are worth investigating in the search for new antibiotics,” Professor Dyson says. “Scientists, historians, and archaeologists can all have something to contribute to this task. It seems that part of the answer to this very modern problem might lie in the wisdom of the past.”

“We will now concentrate on the purification and identification of these antibiotics. We have also discovered additional antibacterial organisms from the same soil cure which may cover a broader spectrum of multi-resistant pathogens.”

The paper “A Novel Alkaliphilic Streptomyces Inhibits ESKAPE Pathogens” has been published in the journal Frontiers in Microbiology.

Countryside road.

Pesticide build-ups are contaminating Europe’s fields

Pesticide use has propelled agriculture to new heights of productivity. However, they’re also eating away at farmlands.

Countryside road.

Image via Pixabay.

Over the last 50 years or so, phytosanitary products have enjoyed wider and wider use in agriculture, especially across developed countries. This helped to bring productivity to levels unheard-of before — but, at least in the European Union, it also degraded the soils.

Putting the ‘pest’ in ‘pesticide’

A duo of scientists participating in the Diverfarming project at the University of Wageningen, Netherlands, report finding traces of pesticide compounds in European agricultural soil samples. Researchers Violette Geissen and Coen J. Ritsema retrieved and analyzed 317 samples of surface agricultural soils from 11 countries in Europe. The soils used in this study belonged to 6 different cropping systems.

All in all, 83% of the samples contained traces of pesticides; the range of such compounds was also pretty impressive — 76 different types of pesticides were identified in the samples. Roughly 58% of that percentage were mixes of pesticides, while the rest (25%) came from a single type of substance. Glyphosate, DDT (banned since the 1970s,) and broad-spectrum fungicides were the main compounds detected.

The discussion around pesticide use revolves roughly around two key themes: the surprising persistence of such compounds in the soil (which this study indicates) and their toxicity to non-objective (non-target) species. Considering that the team worked with surface soil samples specifically, the results point to the ease with which such compounds can become airborne due to air currents.

The Diverfarming project proposes a more rational use of land and other elements of agriculture — water, energy, fertilisers, machinery, and pesticides — to address this issue. Diverfarming is a project financed by the Horizon 2020 Programme of the European Commission, within the challenge of “Food Security, Sustainable Agriculture and Forestry, Marine, Maritime and Inland Water Research and the Bioeconomy,” which draws expertise from members in virtually every country in the Union.

The paper proposes a series of alternatives to current practices in agriculture to help preserve the soil microorganism balance and, by extension, its biodiversity and overall health. These range from the use of new non-persistent pesticides, bio-stimulants, organic composts, or crop diversification — which contributes to balanced insect communities and thus to the absence of pests.

According to the study, the presence of mixes of pesticide residues in the soil is more the rule than the exception, which illustrates the need to evaluate environmental risks in the case of these combined compounds to minimise their impact. The effects of such mixes on the soil need to be investigated further, the team reports.

The paper “Pesticide residues in European agricultural soils – A hidden reality unfolded” has been published in the journal Science of The Total Environment.

Buried away: deep soil holds surprisingly much CO2, but warming is bad news

Scientists have gained a deeper understanding of the global carbon cycle, finding that much of the planet’s carbon dioxide is stored deep beneath soils — with important implications for climate change.

Since we’re kids, we’re taught about natural cycles — the most common two being the water and the carbon cycle. We’re taught that there’s a balance in these cycles, preventing the Earth’s carbon from being released into the atmosphere or being completely absorbed into the water and rocks.

In this period of our planet’s history, this balance is perturbed by the industrial activities of mankind. The basic process is extremely simple: we’re outputting too much carbon dioxide, at a much faster rate than it can be absorbed through natural processes. This process is well-documented, and its effects are also clearly severe, though intricacies and details remain less understood.

For instance, the influence of soils remains somewhat unclear.

“We know less about the soils on Earth than we do about the surface of Mars,” said Marc Kramer, an associate professor of environmental chemistry at WSU Vancouver, whose work appears in the journal Nature Climate Change. “Before we can start thinking about storing carbon in the ground, we need to actually understand how it gets there and how likely it is to stick around. This finding highlights a major breakthrough in our understanding.”

A simple representation of the carbon cycle.

Kramer and colleagues conducted the first global-scale evaluation of the role soil plays in storing carbon. They analyzed soils and climate data from the Americas, New Caledonia, Indonesia and Europe, and drew from more than 65 sites sampled to a depth of six feet from the National Science Foundation-funded National Ecological Observatory Network. In particular, they focused on how carbon is dissolved into the soils, and what are the minerals that help store it.

This let them develop a map of carbon accumulation, and gain a better understanding of the pathway which leads carbon to be trapped in these soils. Spoiler alert: there are few reasons for optimism.

The good news is that according to this estimate, soils currently store about 600 billion gigatons of carbon (two times more than mankind’s output since the Industrial Revolution). However, the bad news is that if temperatures continue to rise, this could severely impede the amount of carbon soils will store. This would happen because water is the main mechanism through which carbon gets dissolved into the soils and even if rainfall remains unchanged, higher temperatures mean less water penetrates the soil. This also helps to explain why wet soils store more carbon than dry ones.

Researchers also found that deeper soils store surprisingly much carbon — but the storage pathway is largely similar. So while carbon store in the deeper parts of the soil won’t be directly affected by rising temperatures, the pathway through which this carbon is stored is altered –. essentially, this pathway relies on water to seep carbon from roots, fallen leaves, and other organic matter, and transport it into the deeper layers, where it remains trapped. Simply put, if there’s less water, there’s less stored carbon.

Generally speaking, wet forests tend to be the most productive environments, as the thick layers of organic matter from which water will leach carbon and transport it to minerals as much as six feet below the surface.

“This is one of the most persistent mechanisms that we know of for how carbon accumulates,” Kramer said.

This isn’t the first study to draw an alarm bell regarding the soils’ impact on carbon levels. Two years ago, another study found that the ability of soils to absorb carbon has been dramatically overestimated, whereas just a few months ago, soil erosion was highlighted as a potential source of additional carbon release into the atmosphere.

The study has been published in Nature Climate Change.

University creates Mars-like soil — and you can buy it dirt cheap

While we’re still a long way from making manned missions to Mars a reality, there’s now a way to bring a piece of Mars back to you — kind of. In a new study, researchers describe a new method to create Mars-like soil, which is very much like the real thing, and costs only $20 / kg (2.2 pounds).

Curiosity’s tracks on Martian soil. Image credits: NASA / JPL.

A Red puzzle

Martian soil is essentially fine regolith — a layer of loose, unconsolidated material which typically includes dust, soil, flakes of rock, and other related materials. We have a lot of regolith on Earth, but Martian regolith is quite different from ours. For instance, on our planet, “soil” is generally considered to include organic components — which is not the case on Mars (even if organic matter does exist on Mars, it’s much rarer than on Earth). So on Mars, we need a different definition for soil — generally, this refers to all unconsolidated material, from small rocks to fine grains, small enough to be moved around by wind.

We know quite a bit about this Martian soil, but the information is disparate; think of it as a puzzle, where we vaguely see the big picture, even though some of the pieces are missing.

For instance, remote sensing has shown that our neighbor features vast expanses of sand and dust and its surface is littered with rocks and boulders. The Martian dust is very fine, and when it remains suspended in the atmosphere, it gives the sky a reddish hue — presumably due to rusting iron minerals formed billions of years ago, when Mars still had vast quantities of water. More modern soil might also be red, due to a different type of oxide. The Phoenix lander showed Martian soil to be slightly alkaline, containing elements such as magnesium, sodium, potassium, and chlorine.

The Curiosity rover brought our understanding of Martian soil even further, discovering minerals such as feldspar, pyroxenes, and olivine — all of which are found on Earth, particularly in basaltic soils (weathered basaltic soils, to be more precise).

However, Curiosity never brought any samples back to Earth, and although a few return missions have, that’s not nearly enough for thorough experimentation. Armed with these samples and many more pieces of information, scientists from the University of Central Florida set out to develop realistic Martian soil, which they call “simulant.”

Constructing soil

Comparison of martian simulants. Image credits: Cannon et al. Icarus.

The reasoning is simple: much like in the movie The Martian, scientists are also considering growing crops on Mars, and seeing what its properties are and what the soil can be used for is key to such pursuits.

“The simulant is useful for research as we look to go to Mars,” said Physics Professor Dan Britt, a member of UCF’s Planetary Sciences Group. “If we are going to go, we’ll need food, water and other essentials. As we are developing solutions, we need a way to test how these ideas will fare.”

Britt works at the confluence of geology and physics, you could hardly imagine someone better suited for developing this project. In the new study, he says that the new simulant “offers vast improvements over previous simulants” and can be used for a myriad of lab tests.

“The composition and physical properties of martian regolith are dramatically better understood compared to just a decade ago, particularly through the use of X-ray diffraction by the Curiosity rover,” the study reads.

“Cooking” the Mars simulant. Image credits: University of Central Florida.

Developing the simulant is somewhat similar to cooking: if you know the chemical makeup (the ingredients) and the process to subject them to (how to cook), you can control your end product — and in this case, the end product looks and acts very much like the real thing. The best part about it? It only costs $20 per kilogram (2.2 pounds) plus shipping — which means it could be easily sent to labs and universities across the world, where a number of experiments can be carried out. NASA’s Kennedy Space Center has already reportedly placed an order for a ton.

“I expect we will see significant learning happening from access to this material,” Britt says.

Cannon also believes it will help accelerate our exploration of the solar system and democratize access to this exploration, as demonstrated by investments already being made by Space X, Blue Origin, and other private companies.

However, this is just one type of simulant — Martian soil comes in many variations, featuring different percentages of clays, sand, and salty dirt. Kevin Cannon, the paper’s lead author and a post-doctoral researcher who works with Britt at UCF, says the team is already working on developing new varieties, which they plan to make commercially available for similarly low prices.

Cannon is in Montana to collect ingredients for a moon simulant this week — the moon also features a regolith soil, though with significant differences from the Martian one.

The study is published and freely available at Icarus.

No bones needed — researchers use DNA in soil to tell if humans were around

Archaeologists might have just come across a game changer after a new study reports a new way of seeing if humans have been around or not.

The average annual temperature of the Denisova cave remains at 0 °C (32 °F), which helped protect the DNA. Image credits: Демин Алексей Барнаул.

For archaeologists, knowing where to look is extremely important. There’s no telling how many sites and even settlements we’ve yet to discover, and what mysteries those might hold. The problem is, it can be really hard to identify these places, and it gets even worse with ancient archaeology when there are almost no structures and no obvious tells.

To a great extent, paleolithic archaeologists rely on human bones to understand the context of a site. Just take the Denisova Cave in Siberia, famous for giving its name to the Denisovans, a species of humans largely similar to Neanderthals. There are plenty of tools there created by some human species, but what species was it? Was it Denisovans, Neanderthals, Homo sapiens… something else? We don’t know. Many believed they were created by Denisovans, because Denisovan bones were abundant in the cave, but the new study claims this is not the case. Even though no Neanderthals bones were found in the area, the paper’s authors confirmed their presence by studying the DNA in the soil.

“This is a game changer for researchers studying our hominin past,” says Christian Hoggard, an archaeologist at Aarhus University who wasn’t involved with the story. His words are echoed by myriad researchers excitedly tweeting the paper: “This is pretty damn incredible,” says Rob Scott, an evolutionary anthropologist at Rutgers. Tom Higham, an Oxford professor who specializes in dating bones, called the discovery a “new era in Paleolithic archaeology.”

The rarity of bones is a major problem for researchers. It’s not extremely rare for scientists to find man-made tools but no bones nearby. The fact that DNA from soil can be analyzed is a big difference.

“Although a rich record of Pleistocene human-associated archaeological assemblages exists, the scarcity of hominin fossils often impedes the understanding of which hominins occupied a site,” the study reads. “Using targeted enrichment of mitochondrial DNA we show that cave sediments represent a rich source of ancient mammalian DNA that often includes traces of hominin DNA, even at sites and in layers where no hominin remains have been discovered.”

Viviane Slon, a researcher at the Max Planck Institute for Evolutionary Anthropology, coordinated a large team of multidisciplinary researchers. After extracting genetic material from sediment samples across four caves in Europe, they carried out an analysis focusing on mitochondrial DNA, only a small portion of the DNA in a eukaryotic cell. Basically, you take the soil sample (not much, less than a teaspoon), use chemical agents to release the genetic material, and then put it in a sequencing machine. However, it’s not really as easy as that. Slon and her team used a clever innovation which relies on the geometrical arrangement of DNA, which is kind of like a jigsaw zipper tightly entwined in a double helix structure. What they did is synthesize a half of it, “baiting” and extracting the other half of the sequence from the solution it was placed in.

The structure of DNA showing with detail showing the structure of the four bases, adenine, cytosine, guanine and thymine. Image credits: Zephyris.

It’s not just human DNA that works with this, they found the DNA of ancient mammals like woolly mammoths and woolly rhinos, before ultimately finding the DNA of Neanderthals, confirming their finds using existing archaeological record. After confirming the results of their method, they move onto the unknown, ultimately concluding that Neanderthals and not Denisovans had created the tools from the Denisova cave. They also confirmed the existence of Neanderthal DNA in Trou Al’Wesse in Belgium, where tools and animal bones have suggested Neanderthal presence, but no Neanderthal bones have ever been found.

There are limits to what this method can do, as the oldest DNA ever analyzed was around 700,000 years old, but in most cases, DNA analysis can’t go that much into the past. Furthermore, you might get some DNA contamination which might be very confusing. Archaeologists analyze things in layers, but there’s no guarantee that DNA found in a layer originated in that layer — it may have migrated from a different layer. Still, the possibilities and potential of this method are extremely exciting.

Journal Reference: Viviane Slon et al — Neandertal and Denisovan DNA from Pleistocene sediments. DOI: 10.1126/science.aam9695.

Study found human habitation promoted forest growth in British Columbia over the past 13,000 years

We’ve often covered the effect human life is having on the environment pretty extensively on ZME Science (see here, here, and here for a few highlights) and for the most part, it’s been pretty grim.

These trees may not be here if the First Nations hadn’t lived in British Columbia for as long as they did.
Image credits Will McInnes / Hakai Institute.

So what gives? Are we doomed to destroy the world (or worlds) around us over and over again in our thirst for resources, or is there any reverse to the coin? University of Waterloo Faculty of Environment Professor Andrew Trant says there is. He led a study in partnership with the University of Victoria and the Hakai Institute which found that the almost 13,000 thousand years of repeated human habitation in British Columbia by the First Nations has actually enhanced temperate rain forest productivity.

The research put together remote-sensed, ecological and archaeological data from coastal sites that have been settled by the First Nations for thousands of years. The trees growing at these sites were found to be taller, wider, and overall in better health than those in the surrounding forest.

And it can all be traced to shell middens and fire.

“It’s incredible that in a time when so much research is showing us the negative legacies people leave behind, here is the opposite story,” said Trant, a professor in Waterloo’s School of Environment, Resources and Sustainability.

“These forests are thriving from the relationship with coastal First Nations. For more than 13,000 years —500 generations—people have been transforming this landscape. So this area that at first glance seems pristine and wild is actually highly modified and enhanced as a result of human behaviour.

Intertidal shellfish gathering has really picked up in the area over the last 6,000 years, leading to an accumulation of deep shell middens in the area. The discarded middens covered thousands of square meters of forest ground, in some cases being deposited in piles more than five meters deep. In what’s probably the most fortunate turnout of littering that I know of, depositing the remains inland brought significant quantities of marine-derived nutrients to the soil. As the shells slowly deteriorated, they leached calcium into the soil, promoting tree growth.

Image credits Will McInnes / Hakai Institute.

The team also found evidence that the use of fire also helped make the forests we see today. Along with the disposal of shells, ash introduced important nutrients to the forest’s soil, increased its pH levels, and improved soil drainage.

The study examined 15 former habitation sites in the Hakai Lúxvbálís Conservancy on Calvert and Hecate Islands using remote-sensed, ecological and archaeological methods to compare forest productivity with a focus on western red cedar. It is the first work to find evidence of long-term use of intertidal resources increasing a forest system’s productivity.

Trant believes that similar findings will occur at archaeological sites along many global coastlines.

“These results alter the way we think about time and environmental impact,” he said. “Future research will involve studying more of these human-modified landscapes to understand the extent of these unexpected changes.”

The full paper, titled “Intertidal resource use over millennia enhances forest productivity” has been published in the journal Nature Communications.


700 year-old farming technique may revolutionize African farming and mitigate climate change

A farming technique practiced by West African villagers for centuries could drastically improve farming throughout the entire continent, as well as mitigate climate change.

Comparison between fertile and unfertile soil. Photo credit: Victoria Frauisn, University of Sussex.

Soil quality is a growing issue in many parts of the world. There are only so many nutrients in the soil, erosion is becoming a bigger problem, and water availability is also tightening up – so finding ways to improve soil quality can go a long way. A global study, led by the University of Sussex in collaboration with soil scientists from Cornell, Accra, and Aarhus Universities and the Institute of Development Studies found an interesting solution for many communities in Africa.

The team analyzed 150 sites in northwest Liberia and 27 sites in Ghana, finding that these highly fertile soils contain 2-3 times more organic carbon than other soils, and they are capable of support far more intensive farming. The solution isn’t new – on the contrary. It has been used in one way or another for hundreds of years. These soils were also poor in nutrients once, but they were treated with charcoal (bio-char) and kitchen waste, and it did wonders. Professor James Fairhead, from the University of Sussex, who initiated the study, said:

“Mimicking this ancient method has the potential to transform the lives of thousands of people living in some of the most poverty and hunger stricken regions in Africa. More work needs to be done but this simple, effective farming practice could be an answer to major global challenges such as developing ‘climate smart’ agricultural systems which can feed growing populations and adapt to climate change.”

This is quite different from simply composting, as turning organic matter into char prevents its complete decomposition. When you use compost, it is good for the soil, but it decomposes completely in a few years (up to 10), releasing all the carbon dioxide and methane. Meanwhile, bio-char won’t fully decompose and will keep the CO2 and methane trapped underground, making soils fertile for a much longer time. The creation of bio-char is something that should come pretty easily for most rural African communities. Disposing of ash, bones and other kinds of organic waste is something they need to do on a day to day basis.

What’s interesting is that a similar practice was employed in South America, though the technique might have been different. Dr Dawit Solomon, the lead author from Cornell University, said:

“What is most surprising is that in both Africa and in Amazonia, these two isolated indigenous communities living far apart in distance and time were able to achieve something that the modern-day agricultural management practices could not achieve until now. The discovery of this indigenous climate smart soil-management practice is extremely timely. This valuable strategy to improve soil fertility while also contributing to climate change mitigation and adaptation in Africa could become an important component of the global climate smart agricultural management strategy to achieve food security.”

Now, it’s just a matter of applying the same technique at a greater scale. If we can do that, this small thing could to a massive difference for the African soils – and the African farmers.

The study entitled “Indigenous African soil enrichment as a climate-smart sustainable agriculture alternative”, has been published in the journal Frontiers in Ecology and Environment and can be found here.


Peak oil – reached. Peak water – reached. Next on the list? Peak soil

Soil is becoming endangered – this is the reality a meeting between experts in Reykjavik has reached. They explain that this has to receive public awareness if we want to feed 9 billion by 2050.

Soil degradation is life degradation


soilThe main culprit is the one also responsible for global warming: Carbon.

“Keeping and putting carbon in its rightful place needs to be the mantra for humanity if we want to continue to eat, drink and combat global warming, concluded 200 researchers from more than 30 countries”.

Indeed, for all the attention the air and water gets, soil seems to be the forgotten child, just because we don’t eat or drink it. But everything we eat comes from it.

“While soil is invisible to most people it provides an estimated 1.5 to 13 trillion dollars in ecosystem services annually,” Glover said at the Soil Carbon Sequestration conference that ended this week.

It’s practically impossible to calculate the benefits that soil brings us – a mere cup of soil contains some 500.000 species, including worms, ants, fungi, bacteria and other microorganisms. 99% of our food comes from it, directly or indirectly, compared to the only 1% we get from oceans.

Soilcleans water, keeps contaminants out of streams and lakes, and prevents flooding; it can also absord massive quantities of carbon. But as hard as it may seem – it’s really fragile.

“It takes half a millennia to build two centimetres of living soil and only seconds to destroy it,” Glover said.

Plowing, removal of crop residues after harvest, and overgrazing all leave soil naked and vulnerable to wind and rain, resulting in gradual, often unnoticed erosion of soil. Erosion not only destroys crops, causes landslides and other catastrophes, but also releases carbon into the air.

“Soil can be a safe place where huge amounts of carbon from the atmosphere could be sequestered,” said Rattan Lal of Ohio State University.

So we’ve pretty much screwed the atmosphere – unless practically all of science that we do now is wrong, that’s a fact. We’re well into doing the same to the water, as a massive, large scale water shortage seems like a matter of time. Are we going to do the same with soil? Are we going to try to milk the cow until it runs totally dry? We know what should be done, we have the technology, and we also have the money for it.

A sad example


About 1000 years ago, when the first settlers arrived there, Iceland was mostly covered by forests, lush meadows and wetlands. By the late 1800s, about 96 percent of all icelandic forrests were gone. Half of the grasslands were destroyed by overgrazing. Humans pushed the land way beyond the limit of sustainability, up to the point where it became barren.

Due to necessity, Iceland pioneered a number of groundbreaking techniques in terms of soil protection, but the results in the past 100 years are moving extremely slowly.

“We’re still fighting overgrazing here,” Halldórsson said.

But the public is living in the urban areas, has forgot these troubles, and is not supporting land restoration anymore.

“The public isn’t supporting land restoration. We’ve forgotten that land is the foundation of life,” Halldórsson said.