Farming is driving force in drying soil in Northern China

Purdue University News: An important agricultural region in China is drying out, and increased farming may be more to blame than rising temperatures and less rain, according to a study spanning 30 years of data. A research team led by Purdue University and China Agricultural University analyzed soil moisture during the growing season in Northern China and found that it has decreased by 6 percent since 1983.

The optimal soil-moisture level for farmland is typically 40 percent to 85 percent of the water holding capacity, and the region's soil is now less than 40 percent and getting drier. If this trend continues, the soil may not be able to support crops by as early as 2090, said study leader Qianlai Zhuang, Purdue's William F. and Patty J. Miller Professor of Earth, Atmospheric and Planetary Sciences and Agronomy.

"The soil moisture declined by 1.5 to 2.5 percent every decade of the study and, while climate change is still a factor, this water depletion appears to be largely driven by human activities," Zhuang said. "A 10 percent decline in soil moisture over the course of a century would have major implications for agriculture and the fresh water supply in this heavily populated area."

Forty percent of the nation's population resides in Northern China, according to the country's population census office. The region also accounts for 65 percent of the nation's cropland, Zhuang said.

"The drying of soil in Northern China has been well documented, but its causes and the impacts of agricultural intensification in general have been understudied," he said. "This information is critical to improvement of agricultural practices and water resource management. The demand for food and water is increasing, but current practices to meet this demand threaten the future security of water resources. Unfortunately, with the growing world population, more and more regions could face the same circumstances of agricultural intensification for food security."...

This is a map of soil moisture trends in Northern China during the growing seasons from 1983-2012. The shading shows the trend in satellite-observed surface soil moisture, and the circles represent monitoring stations within agricultural plots. A Purdue University-led research team found that farming was more of a driver in the drying of the soil than rising temperatures and declining rainfall. The change in volumetric water content is shown. (Purdue University image/Yaling Liu) 

Human security at risk as depletion of soil accelerates

Sarah Yang at the UC Berkeley News Center: Steadily and alarmingly, humans have been depleting Earth’s soil resources faster than the nutrients can be replenished. If this trajectory does not change, soil erosion, combined with the effects of climate change, will present a huge risk to global food security over the next century, warns a review paper authored by some of the top soil scientists in the country.

The paper singles out farming, which accelerates erosion and nutrient removal, as the primary game changer in soil health. “Ever since humans developed agriculture, we’ve been transforming the planet and throwing the soil’s nutrient cycle out of balance,” said the paper’s lead author, Ronald Amundson, a UC Berkeley professor of environmental science, policy and management. “Because the changes happen slowly, often taking two to three generations to be noticed, people are not cognizant of the geological transformation taking place.”

In the paper, published [May 7] in the journal Science, the authors say that soil erosion has accelerated since the industrial revolution, and we’re now entering a period when the ability of soil, “the living epidermis of the planet,” to support the growth of our food supply is plateauing. The publication comes nearly two weeks ahead of the Global Soil Security Symposium at Texas A&M University, a meeting held as part of the declaration of 2015 as the International Year of Soils by the United Nations.

The authors identify the supply of fertilizer as one of the key threats to future soil security. Farmers use three essential nutrients to fertilize their crops: nitrogen, potassium and phosphorous. The paper credits the discovery of synthetic nitrogen production in the early 1900s for significantly increasing crop yields, which in turn supported dramatic growths in global population. Because the process of synthesizing nitrogen is energy-intensive, its supply is dependent on fossil fuels.

...Another threat to soil security relates to its role as a mass reservoir for carbon. Left unperturbed, soil can hold onto its stores of carbon for hundreds to thousands of years. The most recent estimates suggest that up to 2,300 gigatons of carbon are stored in the top three meters of the Earth’s soil – more carbon than in all the world’s plants and atmosphere combined. One gigaton is equal to a billion tons.

...One proposal is to stop discarding nutrients captured in waste treatment facilities. Currently, phosphorous and potassium are concentrated into solid waste rather than cycled back into the soil. Additionally, more efficient management is needed to curtail losses from soil. Excess nitrogen, for example, is considered a pollutant, with the runoff sapping oxygen from the nation’s waterways, suffocating aquatic life and creating dead zones in coastal margins...

A South Korean combine in 1976

Capturing and storing carbon in soil: Is it real and can it scale?

EurekAlert via Arizona State University: Can beef production help restore ecosystems? A team of scientists, advisors and communications specialists are banding together to explore whether ranching management can create robust soils, watersheds and wildlife habitat while sequestering atmospheric carbon dioxide.

The Arizona State University-SoilCarbon Nation team is examining the adaptive multi-paddock (AMP) grazing management technique that involves using small-sized fields to provide short periods of grazing for livestock and long recovery periods for fields. The method mimics the migrations of wild herd animals, such as elk, bison and deer. The science team proposes a whole system science measurement approach in comparing AMP grazing with conventional, continuous grazing methods.

Peter Byck, professor of practice at the School of Sustainability and the Walter Cronkite School of Journalism and Mass Communication at ASU, is helping organize the project. "By using measures - such as the carbon stored, the water absorbed and retained, populations of fungi, bacteria, wild life and insects, and rancher and animal well-being - we are comparing adaptive grazing with conventional grazing to see if the former actually improves ranch ecosystems," he said. "We hope to study and compare 36 ranches located in four diverse eco-regions across the U.S. and southern Canada."

While individual members of the team concentrate on aspects and impacts of various grazing techniques, Byck's focus is to discover whether the methods store carbon in the soil, and if so, which is the most successful.

According to Byck, the idea for the project came from researching Soil Carbon Cowboys, a short Carbon Nation 2.0 film made in collaboration with ASU. His feature documentary, 2011's Carbon Nation, focuses on climate change solutions....

"While filming Soil Carbon Cowboys, we came across ranchers who were adopting healthier grazing practices to rejuvenate their land and their livestock," said Byck. "What they did not know is that they were helping capture a significant amount of carbon dioxide from the air."....

US Agricultural Research Service photo of a cattle herd

NASA launches groundbreaking soil moisture Mapper

A press release from NASA: The Soil Moisture Active Passive (SMAP) observatory, a mission with broad applications for science and society, lifted off at 6:22 a.m. PST (9:22 a.m. EST) Saturday from Vandenberg Air Force Base, California, on a United Launch Alliance Delta II rocket. NASA's Jet Propulsion Laboratory in Pasadena, California, manages SMAP for NASA's Science Mission Directorate in Washington, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland.

...SMAP now begins a three-year mission that will figuratively scratch below Earth's surface to expand our understanding of a key component of the Earth system that links the water, energy and carbon cycles driving our living planet. SMAP's combined radar and radiometer instruments will peer into the top 2 inches (5 centimeters) of soil, through clouds and moderate vegetation cover, day and night, to produce the highest-resolution, most accurate soil moisture maps ever obtained from space.

The mission will help improve climate and weather forecasts and allow scientists to monitor droughts and better predict flooding caused by severe rainfall or snowmelt -- information that can save lives and property. In addition, since plant growth depends on the amount of water in the soil, SMAP data will allow nations to better forecast crop yields and assist in global famine early-warning systems.

"The launch of SMAP completes an ambitious 11-month period for NASA that has seen the launch of five new Earth-observing space missions to help us better understand our changing planet," said NASA Administrator Charles Bolden. "Scientists and policymakers will use SMAP data to track water movement around our planet and make more informed decisions in critical areas like agriculture and water resources."....

NASA's Soil Moisture Active Passive (SMAP) observatory lifts off from Space Launch Complex 2 West at California's Vandenberg Air Force Base, beginning a three-year mission to map Earth's vital moisture hidden in the soils beneath our feet. Image credit: NASA/Bill Ingalls 

Save civilization — grow topsoil

Jeffrey Carter in the Western Producer: Farmers need to move beyond conserving topsoil and start growing it, according to a Vermont grazier, educator and consultant. “The best we’ve been able to do is that we’re losing 10 times more soil than is being grown. At least, that’s the latest numbers I’ve seen,” Abe Collins told the Ecological Farmers of Ontario conference in Orillia in early December.

Collins is part of a small group of agriculturalists who want to take that next step. He is co-founder of the Soil Carbon Coalition, a non-profit organization dedicated to transforming atmospheric carbon into soil organic matter.

“If topsoil is renewable, at least that’s the experience of our community, we all need to learn how to grow it,” he said. “Nearly everything rests on us to grow the topsoil so that the rest of society can survive and civilization continues.” Collins encourages farmers to evaluate their current practices and make the necessary changes to build their soil in a real and substantial manner.

The first step is to establish a series of GPS-located, strategically placed, four-by-four metre, permanent plots that can be monitored over the coming years. Locations should be photographed and ecological observations such as earthworm activity recorded. The water infiltration capacity must be measured with a tension infiltrometer and core samples taken to measure soil carbon.

Returning to the same location each year allows farmers, foresters and other landowners to monitor how the changes they are making are improving their soils. Collins said there is no one path to building the capacity of topsoil and increasing soil organic matter. Progress will have been made if farmers can achieve real, measurable gains....

Cracked soil, shot by Jeroen Moes, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license

Soil’s large carbon stores could be freed by increased CO2, plant growth

A press release from Princeton University: An increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet — soil.

Researchers based at Princeton University report in the journal Nature Climate Change that the carbon in soil — which contains twice the amount of carbon in all plants and Earth’s atmosphere combined — could become increasin
gly volatile as people add more carbon dioxide to the atmosphere, largely because of increased plant growth. The researchers developed the first computer model to show at a global scale the complex interaction between carbon, plants and soil, which includes numerous bacteria, fungi, minerals and carbon compounds that respond in complex ways to temperature, moisture and the carbon that plants contribute to soil.

Although a greenhouse gas and pollutant, carbon dioxide also supports plant growth. As trees and other vegetation flourish in a carbon dioxide-rich future, their roots could stimulate microbial activity in soil that in turn accelerates the decomposition of soil carbon and its release into the atmosphere as carbon dioxide, the researchers found.

This effect counters current key projections regarding Earth’s future carbon cycle, particularly that greater plant growth could offset carbon dioxide emissions as flora take up more of the gas, said first author Benjamin Sulman, who conducted the modeling work as a postdoctoral researcher at the Princeton Environmental Institute. “You should not count on getting more carbon storage in the soil just because tree growth is increasing,” said Sulman, who is now a postdoctoral researcher at Indiana University.

On the other hand, microbial activity initiated by root growth could lock carbon onto mineral particles and protect it from decomposition, which would increase long-term storage of carbon in soils, the researchers report.

Whether carbon emissions from soil rise or fall, the researchers’ model depicts an intricate soil-carbon system that contrasts starkly with existing models that portray soil as a simple carbon repository, Sulman said. An oversimplified perception of the soil carbon cycle has left scientists with a glaring uncertainty as to whether soil would help mitigate future carbon dioxide levels — or make them worse, Sulman said....

The model projected changes (above) in global soil carbon as a result of root-soil interactions, with blue indicating a greater loss of soil carbon to the atmosphere. (Image by Benjamin Sulman, Princeton Environmental Institute)

The soil, silent ally against hunger in Latin America

Marianella Jarroud in IPS via Tierramerica: Latin America and the Caribbean should use sustainable production techniques to ensure healthy soil, the basic element in agriculture, food production and the fight against hunger.

“Keeping the soil healthy makes food production possible,” said Raúl Benítez, regional director for the United Nations Food and Agriculture Organisation (FAO). “Without good soil, food production is undermined, and becomes more difficult and costly. We are often not aware that it can take 1,000 years to generate one centimetre of healthy soil, but we can lose that centimetre in a few seconds as a result of pollution, toxic waste, or misuse of the soil,” he said in an interview with Tierramérica.

Despite its importance, 33 percent of the planet’s soil is degraded by physical, chemical or biological causes, which is reflected in a reduction in plant cover, soil fertility, and pollution of the soil and water, and which leads to impoverished harvests, FAO warns.

Latin America and the Caribbean have the largest amount of potential arable land in the world. The worst degradation of soil is in Central America and southern Mexico, where it affects 26 percent of the land. In South America that proportion is 14 percent....

Some dirt, shot by 4028mdk09, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

World losing 2,000 hectares of farm soil daily to salt-induced degradation

A press release from United Nations University: Salt-spoiled soils worldwide: 20% of all irrigated lands — an area equal to size of France; Extensive costs include $27 billion+ in lost crop value / year. UNU study identifies ways to reverse damage, says every hectare needed to feed world’s fast-growing population.

Every day for more than 20 years, an average of 2,000 hectares of irrigated land in arid and semi-ari
d areas across 75 countries have been degraded by salt, according to a new study — Economics of Salt-induced Land Degradation and Restoration — published today by the UNU Institute for Water, Environment and Health (UNU-INWEH).

Currently an area the size of France is affected — about 62 million hectares (20 percent) of the world’s irrigated lands, up from 45 million hectares in the early 1990s. Salt-induced land degradation occurs in arid and semi-arid regions where rainfall is too low to maintain regular percolation of rainwater through the soil and where irrigation is practiced without a natural or artificial drainage system.

Irrigation practices without drainage management trigger the accumulation of salts in the root zone, affecting several soil properties and reducing productivity. “To feed the world’s anticipated nine billion people by 2050, and with little new productive land available, it’s a case of all lands needed on deck,” says principal author Manzoor Qadir, Assistant Director of the Water and Human Development programme at UNU-INWEH. ”We can’t afford not to restore the productivity of salt-affected lands.”

Zafar Adeel, Director of UNU-INWEH, notes that the UN Food and Agriculture Organization projects a need to produce 70 percent more food by 2050, including a 50 percent rise in annual cereal production to about 3 billion tonnes....

Campbell's River in the Murray-Darling Basin, shot by Rangasyd, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Newly discovered microbe Is key in climate change

Daniel Stolte at the University of Arizona News: Tiny soil microbes are among the world's biggest potential amplifiers of human-caused climate change, but whether microbial communities are mere slaves to their environment or influential actors in their own right is an open question. Now research by an international team of scientists from the U.S., Sweden and Australia, led by University of Arizona scientists, shows that a single species of microbe, discovered only recently, is an unexpected key player in climate change.

The findings, published in the journal Nature, should help scientists improve their simulations of future climate by replacing assumptions about the different greenhouse gases emitted from thawing permafrost with new understanding of how different communities of microbes control the release of these gases.

Earlier this year, the international team discovered that a single species of microbe, previously undescribed by science, was prominent in permafrost soils in northern Sweden that have begun to thaw under the effect of globally rising temperatures. Researchers suspected that it played a significant role in global warming by liberating vast amounts of carbon stored in permafrost soil close to the Arctic Circle in the form of methane, a powerful greenhouse gas trapping heat in the Earth's atmosphere. But the actual role of this microbe — assigned the preliminary name Methanoflorens stordalenmirensis, which roughly translates to "methane-bloomer from the Stordalen Mire" — was unknown.

The new research nails down the role of the new microbe, finding that the sheer abundance of Methanoflorens, as compared to other microbial species in thawing permafrost, should help to predict the collective impact on future climate change.
"If you think of the African savanna as an analogy, you could say that both lions and elephants produce carbon dioxide, but they eat different things," said senior author Scott Saleska, an associate professor in the UA’s Department of Ecology and Evolutionary Biology and director of the UA's new Ecosystem Genomics Institute. "In Methanoflorens, we discovered the microbial equivalent of an elephant, an organism that plays an enormously important role in what happens to the whole ecosystem."…

"Autumn landscape with fox," Bruno Liljefors - Bukowskis,public domain

Carbon stored in the world’s soils more vulnerable to climate change than expected

A press release from the University of Exeter: The response of soil microbial communities to changes in temperature increases the potential for more carbon dioxide to be released from the world's soils as global temperatures rise, scientists have revealed.

The potential for global warming to stimulate decomposition rates in soils, and thus release large quantities of carbon dioxide to the atmosphere, has long been considered to be one of the potentially most important positive feedbacks to climate change.

However, the results from more recent studies have suggested that responses within microbial communities could greatly reduce, or even eliminate, the potential for soil carbon losses under global warming.

This key idea was tested using soils collected from a thermal gradient from the Arctic to the Amazon rainforest. The results, published in Nature, show that, contrary to expectations, microbial community responses resulted in an overall increase, rather than a decrease, in the effects of temperature on rates of carbon dioxide release from soils.

Dr Kristiina Karhu of the University of Helsinki, and lead author of the paper, said: “Because soils store more than twice as much carbon than the atmosphere, changes in rates of decomposition and carbon dioxide release from soil could be very important. Our findings suggest that warming will increase the activity of soil microbes to a greater extent than was previously expected, which could have implications for future rates of climate change.”...

Some soil in the Netherlands, shot by FotoDutch , Wikimedia Commons, under the Creative Commons 3.0 license

UN agency calls for urgent action to protect global soil from depletion, degradation

UN News Centre:  The United Nations Food and Agriculture Organization (FAO) is calling for urgent action to improve the health of the world's limited soil resources to ensure that future generations have enough supplies of food, water and energy.

"Soil is the basis for food, feed, fuel and fibre production," Maria Helena Semedo, FAO Deputy Director-General, said in a news release issued today. "Without soils we cannot sustain life on earth and where soil is lost it cannot be renewed on a human timeline. The current escalating rate of soil degradation threatens the capacity of future generations to meet their needs.”

Government officials and experts are meeting today in Rome for a three-day meeting of the Global Soil Partnership – which brings together a broad range of stakeholders stressing the need for governments to preserve soil. Under its Global Plans of Action, leaders have endorsed a series of measures to safeguard soil resources through strong regulation and investment. Without soils we cannot sustain life on earth and where soil is lost it cannot be renewed on a human timeline. The current escalating rate of soil degradation threatens the capacity of future generations to meet their needs.

"We need commitments from countries and civil society to put the plan into reality. This requires political will and investments to save the precious soil resources our food production systems depend on," Ms. Semedo said.

Experts at the conference warn that some 33 per cent of world soil is already moderately to highly degraded due to erosion, nutrient depletion, acidification, urbanization, and chemical pollution. And the growing global population – which is expected to exceed 9 billion by 2050, resulting in a 60 per cent increase in the demand for food, feed and fibre – will put an even greater strain on land resources....

Image by 4028mdk09, Wikimedia Commons, under the Creative Commons 3.0 license

'Peak soil' threatens future global food security

Nigel Hunt and Sarah Mcfarlane in Reuters: The challenge of ensuring future food security as populations grow and diets change has its roots in soil, but the increasing degradation of the earth's thin skin is threatening to push up food prices and increase deforestation.

 While the worries about peaking oil production have been eased by fresh sources released by hydraulic fracturing, concern about the depletion of the vital resource of soil is moving center stage.  "We know far more about the amount of oil there is globally and how long those stocks will last than we know about how much soil there is," said John Crawford, Director of the Sustainable Systems Program in Rothamsted Research in England.  "Under business as usual, the current soils that are in agricultural production will yield about 30 percent less than they would do otherwise by around 2050."

Surging food consumption has led to more intensive production, overgrazing and deforestation, all of which can strip soil of vital nutrients and beneficial micro-organisms, reduce its ability to hold water and make it more vulnerable to erosion.

Such factors, exacerbated by climate change, can ultimately lead to desertification, which in parts of China is partly blamed for the yellow dust storms that can cause hazardous pollution in Asia, sometimes even severe enough to cross the Pacific Ocean and reduce visibility in the western United States....

An archive shot of the Dust Bowl in the Texas Panhandle, original date not given, processed by Capmo, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Kudzu can release soil carbon, accelerate global warming

A press release from Clemson University: Clemson University scientists are shedding new light on how invasion by exotic plant species affects the ability of soil to store greenhouse gases. The research could have far-reaching implications for how we manage agricultural land and native ecosystems.

In a paper published in the scientific journal New Phytologist, plant ecologist Nishanth Tharayil and graduate student Mioko Tamura show that invasive plants can accelerate the greenhouse effect by releasing carbon stored in soil into the atmosphere.

Since soil stores more carbon than both the atmosphere and terrestrial vegetation combined, the repercussions for how we manage agricultural land and ecosystems to facilitate the storage of carbon could be dramatic.

In their study, Tamura and Tharayil examined the impact of encroachment of Japanese knotweed and kudzu, two of North America’s most widespread invasive plants, on the soil carbon storage in native ecosystems.

They found that kudzu invasion released carbon that was stored in native soils, while the carbon amassed in soils invaded by knotweed is more prone to oxidation and is subsequently lost to the atmosphere. The key seems to be how plant litter chemistry regulates the soil biological activity that facilitates the buildup, composition and stability of carbon-trapping organic matter in soil.

“Our findings highlight the capacity of invasive plants to effect climate change by destabilizing the carbon pool in soil and shows that invasive plants can have profound influence on our understanding to manage land in a way that mitigates carbon emissions,” Tharayil said....

Kudzu engulfing trees in Atlanta, Georgia, shot by Scott Ehardt, public domain

Researchers question published no-till soil organic carbon sequestration rates

A press release from the University of Illinois: For the past 20 years, researchers have published soil organic carbon sequestration rates.  Many of the research findings have suggested that soil organic carbon can be sequestered by simply switching from moldboard or conventional tillage systems to no-till systems. However, there is a growing body of research with evidence that no-till systems in corn and soybean rotations without cover crops, small grains, and forages may not be increasing soil organic carbon stocks at the published rates.

“Some studies have shown that both moldboard and no-till systems are actually losing soil organic carbon stocks over time,” said University of Illinois soil scientist Ken Olson who led the review.

The review was conducted by a team of senior researchers from universities in Illinois, Wisconsin, Iowa, and Ohio who studied the published soil science and tillage literature related to soil organic carbon sequestration, storage, retention, and loss. After examining hundreds of original research and summary papers, 120 papers on all sides of the soil organic carbon sequestration, storage, retention, and loss issue were selected for review and analysis.

Olson explained that the difference between the no-till and moldboard plots at the end of a long-term study is only a measure of net soil organic carbon storage difference between treatments and does not support soil organic carbon sequestration claims. No-till systems on sloping and eroding sites retain more soil organic carbon in the surface from 0 to 15 centimeters when compared to moldboard as a result of less disturbance and less soil erosion and transport of soil organic carbon-rich sediment off the plots....

One fifth of China's farmland polluted

Jennifer Duggan in the Guardian (UK): A fifth of China's farmland is polluted, according to an offical report based on the results of an extensive survey. Soil pollution has long been a concern in China due to the country's rapid industrialisation and the report carried on the website of the Ministry of Environmental Protection confirms the extent of the problem. The report states that pollutants in more than 16% of Chinese soil exceeds national standards and that figure rises to 20% for arable land.

It describes the situation as "not optimistic" and said said that the quality of farmland is worrying while deserted industrial and mining land is seriously polluted. The main causes of soil pollution are industry and agriculture, according to the report. Cadmium, nickel and arsenic are the top three pollutants found.

The survey was carried out over seven years, ending in December 2013 and covered around 630 square kilometers of land across the country. According to state media, the survey took around 100,000 samples. Almost 70% of the samples were found to be "lightly polluted" with pollution levels twice the national standard. Around 7% were found to be "heavily polluted" with levels more than five times the national standard.

Most of the affected farmland lies along the eastern coast which is the most developed region and home to much of the country's heavy industry. Heavy metal pollution was particularly bad in the southwest of the country, the report found....

A farm in China, shot by Laika ac, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Deforestation of sandy soils a greater threat to climate change

Yale News: Deforestation may have far greater consequences for climate change in some soils than in others, according to new research led by Yale University scientists — a finding that could provide critical insights into which ecosystems must be managed with extra care because they are vulnerable to biodiversity loss and which ecosystems are more resilient to widespread tree removal.

In a comprehensive analysis of soil collected from 11 distinct U.S. regions, from Hawaii to northern Alaska, researchers found that the extent to which deforestation disturbs underground microbial communities that regulate the loss of carbon into the atmosphere depends almost exclusively on the texture of the soil. The results were published in the journal Global Change Biology.

“We were astonished that biodiversity changes were so strongly affected by soil texture and that it was such an overriding factor,” said Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies and lead author of the study. “Texture overrode the effects of all the other variables that we thought might be important, including temperature, moisture, nutrient concentrations, and soil pH.”

...A serious consequence of deforestation is extensive loss of carbon from the soil, a process regulated by subterranean microbial diversity. Drastic changes to the microbial community are expected to allow more CO2 to escape into the atmosphere, wi
th the potential to exaggerate global warming.

...According to the researchers, particles in fine, clay-like soil seem to have a larger surface area to bind nutrients and water. This capacity might buffer soil microbes against the disturbance of forest removal, they said. In contrast, sandy soils have larger particles with less surface area, retaining fewer nutrients and less organic matter....

This heat map shows the areas of the United States where the soil microbial biomass is susceptible to changes in vegetation cover. From the Yale News website

Deer proliferation disrupts a forest’s natural growth

A press release by Joe Schwartz from Cornell University: By literally looking below the surface and digging up the dirt, Cornell researchers have discovered that a burgeoning deer population forever alters the progression of a forest’s natural future by creating environmental havoc in the soil and disrupting the soil’s natural seed banks. The study, “Deer Browsing Delays Succession by Altering Aboveground Vegetation and Belowground Seed Banks,” was published online March 7 in PLOS ONE.

“Deer are slowing down forest succession or natural establishment. In fact, the deer are preventing forests from establishing,” says Anurag Agrawal, Cornell professor of ecology and evolutionary biology, a co-author on the paper. Deer typically prefer to eat native, woody plants and rebuff invasive species. The study showed that when deer consume native plants, the non-native species are left to flourish, dropping seed in the soil.

As forests normally mature, their grasses give way to herbs and shrubs, and then new trees eventually take root. Expanding deer populations in the Northeast, however, stall forest development and promote the growth of thorny thickets of buckthorn, viburnum and multiflora rose bushes. If deer leave the forests alone, such trees as cottonwood, locust and sumac can sprout and grow unimpeded.

The researchers found that the impacts of deer grazing on vegetation were severe and resulted in bare soil and reduced plant biomass, less recruitment of woody species and relatively fewer native species. And the deer’s negative impact on seed banks resulted in significantly decreased overall species richness and relatively more short-lived species of both annual and biennial plants.

...“It’s obvious that the deer are affecting the above-ground species, but it’s like an iceberg. There are major effects below the soil surface. We are seeing a divergence of seeds contained within the soil from what should be there,” says DiTommaso. “We are not seeing the seeds of woody plants. Instead, we’re seeing an escalation of non-native seed and the virtual elimination of woody plant seeds.”...

A deer in Raleigh, North Carolina, shot by Clay Heaton, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

We’ll rise or fall on the quality of our soil

A press release from the University of Witwatersrand: Great civilisations have fallen because they failed to prevent the degradation of the soils on which they were founded. The modern world could suffer the same fate. This is according to Professor Mary Scholes and Dr Bob Scholes who have published a paper in top scientific journal, Science, which describes how the productivity of many lands has been dramatically reduced as a result of soil erosion, accumulation of salinity, and nutrient depletion.

Mary Scholes“Cultivating soil continuously for too long destroys the bacteria which convert the organic matter into nutrients,” says Mary Scholes, who is a Professor in the School of Animal, Plant and Environmental Sciences at Wits University.

Although improved technology – including the unsustainably high use of fertilisers, irrigation, and ploughing – provides a false sense of security, about 1% of global land area is degraded every year. In Africa, where much of the future growth in agriculture must take place, erosion has reduced yields by 8% and nutrient depletion is widespread.

“Soil fertility is both a biophysical property and a social property – it is a social property because humankind depends heavily on it for food production,” says Bob Scholes, who is a systems ecologist at the Council for Scientific and Industrial Research.

...Replacing the fertility-sustaining processes in the soil with a dependence on external inputs has also made the soil ecosystem, and humans, vulnerable to interruptions in the supply of those inputs, for instance due to price shocks.

However, it is not possible to feed the current and future world population with a dogmatically “organic” approach to global agriculture. Given the large additional area it would require, such an approach would also not avert climate change, spare biodiversity, or purify the rivers.

To achieve lasting food and environmental security, we need an agricultural soil ecosystem that more closely approximates the close and efficient cycling in natural ecosystems, and that also benefits from the yield increases made possible by biotechnology and inorganic fertilisers.

Soil profile from the US Department of Agriculture

Climate change to disrupt soil nutrients in drylands

Jan Piotrowski in SciDev.net: The increased aridity expected this century as a result of climate change may disrupt the balance of key soil nutrients with a knock-on effect on soil fertility threatening livelihoods of more than two billion people, a study finds.

The drop in nitrogen and carbon concentrations that occurs as soils become dryer could have serious effects on ecosystem services such as food production, carbon storage and biodiversity, according to the Nature paper published today.

Loss of nitrogen and carbon, which are the basic building blocks of living organisms, drastically affects land’s productivity, says Fernando T. Maestre, a biologist and geologist from King Juan Carlos University, Spain, and a co-author of the report. “If plant productivity is reduced, the capability of the land to support livestock and crops will be affected and this will have a big impact on people who depend on them,” he tells SciDev.Net.

Drylands make up more than 40 per cent of the world's land area, and host a similar proportion of the world’s population. Many are expected to get drier because of climate change.

The study measured the nitrogen, carbon and phosphorus content of soil at 224 sites across all continents except Antarctica, which together represent a wide range of soil and vegetation types, climates and species diversity. As ecosystems became more arid, it found, both nitrogen and carbon concentrations decreased, which may significantly impair plant and microbial activity, with knock-on effects on organic decomposition and plant growth....

The Spider Rock Overlook at Canyon de Chelly in Arizona, National Park Service

New soil testing kit for developing countries

A press release from the Soil Science Society of America: Researchers at the University of Maryland and Columbia University have developed a new soil testing kit designed to help farmers in third world countries. On-the-spot soil testing could have major impact in improving crop yields due to poor soils. The kit contains battery-operated instruments and safe materials for agricultural extension agents to handle in the field. They can test for the availability of nitrogen, phosphorus, sulfur, and potassium, as well as active organic matter, and certain soil physical limitations. The raw results of the tests are sent by cell phone to a central website. Then, calculations are made and recommendations are delivered back to the extension agent.

The kit, called SoilDoc, is the culmination of several years of work in Africa by Ray Weil, PhD. Weil, a soil scientist, spent his 2009 sabbatical working with the Millennium Villages Project in the some of the poorest areas of Africa. He started carrying common soil testing items in his backpack, but found he needed more. Back in the US, he discovered items used for testing home aquariums that would also work for soil tests. Upon returning to Africa, he adapted them with good results, carrying a larger toolkit. A colleague, Pedro Sanchez, a well-known scientist fighting world hunger, suggested that Weil create a product around his homemade kit. Sanchez brought the resources of Columbia University’s Ag and Food Security Center to bear on the project.

A post-doctoral researcher at Sanchez’s Center, Lydiah Gatere, recently rolled out the SoilDoc product. She trained 16 Tanzanian and Nigerian extension personnel. The group plans to conduct more training workshops in 2014 for Tanzania, Nigeria and possibly additional countries. Their vision is to train the trainers: thousands of extension agents, many with little more than a high school education, will then be consultants. They will be ready to diagnose soil fertility problems and offer recommendations to many thousands of “smallholder farmers.” These farmers work on less than 5 acres. The ultimate goal is to significantly increase crop production and food security in Africa....

Right idea, wrong continent: Soil testing in Yuma, Arizona, photo by Jeff Vanuga, USDA Natural Resources Conservation Service.