Tag: WSU

Washington State University researchers have developed a way to assess soil health by measuring the electric current produced by its tiniest microbes.

The team used a probe originally developed to measure the electrochemical signal of microbes in aquatic environments and tested it on healthy and unhealthy soil samples to measure microbial metabolism and other indicators of soil health. This proof-of-concept research, published in Journal of Electrochemical Society, could someday lead to a simple, real-time test for farmers to determine whether soil is productive.

“Soil underpins all the food we eat, and most of it is degraded worldwide,” said Maren Friesen, an associate professor in the Departments of Plant Pathology and Crop and Soil Sciences and a co-author on the study. “One of the biggest barriers to improving soils is not being able to have rapid, real-time measurement to develop appropriate management strategies for them. This sensor has the potential to be able to do real-time measurements not just of the structure of the soil, but how it’s actually functioning. It would be a huge advance in the field.”

“I believe this is one of our most significant works and will have a high impact on soil health determination,” said Haluk Beyenal, professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering and corresponding author on the paper.

Other co-authors on the study include postdoctoral research fellow, Abdelrhman Mohamed, and graduate students Eduardo Sanchez and Natalie Sanchez.

Soil health is critically important to agriculture and crop success worldwide, but measuring it is not straightforward. Farmers and researchers use soil chemistry, nutrient analysis, texture and pH measurements to gain understanding of soil’s physical and chemical properties. While that information can be valuable, it doesn’t always reflect how productive the soil actually is.

That’s because a key to soil productivity is how microbes function, said Friesen. Billions of bacteria, fungi and other organisms play critical roles in nutrient mobilization and provisioning, defense against pathogens and plant growth. But, until now, there has been no simple, real-time way to measure the microbial activity.

“What makes a soil beneficial for a plant is that it is alive and contains all these bacteria and fungi,” she said.

In the new paper, the WSU research team was able to measure current through the soil to determine microbial activity and distinguish healthy and unhealthy soils.

The researchers used a probe that they developed a few years ago to measure the electrochemical signal of microbes in aquatic environments. Similar to how humans eat and breathe, microorganisms take in food and then use electrons liberated during metabolism for their energy. Finally, microbes give these electrons to an acceptor molecule such as oxygen. The probe the team developed replaces these acceptor molecules with an electrode. Using this electrode, they can then measure the electric current and get an idea of the magnitude of microbial activity.

“We are able to measure metabolic rate of the microbes by capturing electrons that are released as a part of metabolism,” said Mohamed, a postdoctoral researcher in the Voiland School. “We’re watching the microbes breathe in the soil.”

The two soil samples the researchers used were collected from the R.J. Cook Agronomy Farm and looked nearly identical to each other in terms of their soil composition. They were both collected from plots that had not been tilled, were relatively high in organic matter, and had the same pH and soil type. But, the researchers had data showing that one of the soils had been significantly more productive in its wheat yield than the other.

The researchers found that the more productive soil produced an electric current while the less productive soil produced almost no current – about 1% of the more productive soil.

“There was a really dramatic difference in the amount of current generated,” said Friesen.

They also found another difference between the two soils in the open circuit potential measured in the soil. When they added sugar to stimulate metabolic activity, the researchers also observed the electrochemical signals change in the healthy and unhealthy soil samples converging, which suggests that the sugar addition stimulated the microbial activity in both soil types.

“We could see that in a couple of days, the microbes in the soil started to respire,” Mohamed said.

With just the two soil samples compared initially, the researchers say their idea is still just a proof of concept. They have many additional questions, such as what the creatures are doing to generate current and what specific microorganisms might be in the samples to create productive soil.

“We have two different signals, but what do they really tell in terms of the fundamental parameters of the soil?” said Mohamed. “Both parameters tell slightly different things, and we need to work on their interpretation.”

They also want to test a lot more soils, including in actual farm fields rather than in the controlled setting of a laboratory. They hope to eventually develop a portable probe that could be inserted directly into the soil to provide real-time information.

“In terms of working towards a just society with sustainable global food production, I feel this has the potential to be a game-changing technology,” Friesen said. — By Tina Hilding, Voiland College of Engineering & Architecture, Washington State University

Droughts occurring at the same time across different regions of the planet could place an unprecedented strain on the global agricultural system and threaten the water security of millions of people, according to a new study in Nature Climate Change.

A Washington State University (WSU)-led research team analyzed climate, agricultural and population growth data to show continuing fossil fuel dependence will increase the probability of co-occurring droughts 40% by the mid-21st century and 60% by the late 21st century, relative to the late-20th century. That comes out to an approximately ninefold increase in agricultural and human population exposure to severe co-occurring droughts unless steps are taken to lower carbon emissions.

“There could be around 120 million people across the globe simultaneously exposed to severe compound droughts each year by the end of the century,” said lead author Jitendra Singh, a former postdoctoral researcher at the WSU School of the Environment now at ETH Zurich, Switzerland. “Many of the regions our analysis shows will be most affected are already vulnerable and so the potential for droughts to become disasters is high.”

The elevated risk of compound droughts estimated by Singh and colleagues is a result of a warming climate coupled with a projected 22% increase in the frequency of El Niño and La Niña events, the two opposite phases of the El Niño Southern Oscillation (ENSO).

The researchers’ projections show that nearly 75% of compound droughts in the future will coincide with these irregular but recurring periods of climatic variation in the world’s oceans, which have played a large role in some of the greatest environmental disasters in world history.

For example, El Nino-fueled droughts that concurrently occurred across Asia, Brazil and Africa during 1876-1878 led to synchronous crop failures, followed by famines that killed more than 50 million people.

“While technology and other circumstances today are a lot different than they were in the late 19th century, crop failures in multiple breadbasket regions still have the potential to affect global food availability,” said study coauthor Deepti Singh, an assistant professor in the WSU School of the Environment.  “This could in turn increase volatility in global food prices, affecting food access and exacerbating food insecurity, particularly in regions that are already vulnerable to environmental shocks such as droughts.”

The researchers’ analysis specifically focused on ten regions of the planet that receive most of their rainfall during June-September, have high variability in monthly summer precipitation and are affected by ENSO variations, factors that lead to an increased potential for co-occurring drought. Several of the regions analyzed include important agricultural regions and countries that are currently facing food and water insecurity.

Their results indicate areas of North and South America are more likely to experience compound droughts in a future, warmer climate than regions of Asia, where much of the agricultural land is projected to become wetter.

Food produced in the Americas could therefore be more susceptible to climatic hazards. For instance, the United States is a major exporter of staple grains and currently ships maize to countries across the globe. Even a modest increase in the risk of compound droughts in the future climate could lead to regional supply shortfalls that could in turn cascade into the global market, affecting global prices and amplifying food insecurity.

“The potential for a food security crisis increases even if these droughts aren’t affecting major food producing regions but rather many regions that are already vulnerable to food insecurity,” said coauthor Weston Anderson, an assistant research scientist at the Earth System Science Interdisciplinary Center at the University of Maryland. “Simultaneous droughts in food insecure regions could in turn amplify stresses on international agencies responsible for disaster relief by requiring the provision of humanitarian aid to a greater number of people simultaneously.”

There is some good news, Anderson said. The researchers’ work is based on a high fossil fuel emissions scenario, and in recent years, the global community has made progress toward lowering carbon emissions which would greatly mitigate the frequency and intensity of co-occurring droughts by the end of the 21st century.

Also, the occurrence of nearly 75% of compound droughts alongside ENSO events in the future climate highlights the potential to predict where these droughts may occur with a lead time of up to nine months.

“This means that co-occurring droughts during ENSO events will likely affect the same geographical regions they do today albeit with greater severity,” said Deepti Singh. “Being able to predict where these droughts will occur and their potential impacts can help society develop plans and efforts to minimize economic losses and reduce human suffering from such climate-driven disasters.”

Moving forward the researchers plan to take a closer look at how co-occurring droughts will affect various aspects of the global food network, how vulnerable communities are affected by and adapting to such climate extremes, as well as how society can be better prepared to manage the risk of increasing simultaneous disasters.

Collaborators for the project included researchers from WSU, Oak Ridge National Laboratory, the University of Massachusetts, Lowell, Columbia University and the Indian Institute of Technology Gandhinagar, India. — By Will Ferguson, Washington State University