Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biochar alters water flow to improve sand and clay

25.09.2014

Research shines light on soil additive's seemingly contradictory benefits

As more gardeners and farmers add ground charcoal, or biochar, to soil to both boost crop yields and counter global climate change, a new study by researchers at Rice University and Colorado College could help settle the debate about one of biochar's biggest benefits -- the seemingly contradictory ability to make clay soils drain faster and sandy soils drain slower.


Rebecca Barnes (front) and Morgan Gallagher conduct hydrology experiments at Rice University in 2013.

The study, available online this week in the journal PLOS ONE, offers the first detailed explanation for the hydrological mystery.

"Understanding the controls on water movement through biochar-amended soils is critical to explaining other frequently reported benefits of biochar, such as nutrient retention, carbon sequestration and reduced greenhouse gas emissions," said lead author Rebecca Barnes, an assistant professor of environmental science at Colorado College, who began the research while serving as a postdoctoral research associate at Rice.

Biochar can be produced from waste wood, manure or leaves, and its popularity among do-it-yourselfers and gardening buffs took off after archaeological studies found that biochar added to soils in the Amazon more than 1,000 years ago was still improving the water- and nutrient-holding abilities of those poor soils today.

Studies over the past decade have found that biochar soil amendments can either increase or decrease the amount of water that soil holds, but it has been tough for experts to explain why this occurs, due partly to conflicting results from many different field tests.

In the new study, biogeochemists at Rice conducted side-by-side tests of the water-holding ability of three soil types -- sand, clay and topsoil -- both with and without added biochar. The biochar used in the experiments, which was derived from Texas mesquite wood, was prepared to exacting standards in the lab of Rice geochemist Caroline Masiello, a study co-author, to ensure comparable results across soil types.

"Not all biochar is created equal, and one of the important lessons of recent studies is that the hydrological properties of biochar can vary widely, depending on the temperature and time in the reactor," Masiello said. "It's important to use the right recipe for the biochar that you want to make, and the differences can be subtle. For scientific studies, it is critical to make sure you're comparing apples to apples."

Barnes said the team chose to make its comparison with simple, relatively homogenous soil materials to compare results to established hydrologic models that relate water flow to a soil's physical properties, like bulk density and porosity.

"This is what helped us explain the seeming disconnect that people have noted when amending soils with biochar," she said. "Biochar is light and highly porous. When biochar is added to clay, it makes the soil less dense and it increases hydraulic conductivity, which makes intuitive sense. Adding biochar to sand also makes it less dense, so one would expect that soil to drain more quickly as well; but in fact, researchers have found that biochar-amended sand holds water longer."

Study co-author Brandon Dugan, assistant professor of Earth science at Rice, said, "We hypothesize that this is likely due to the presence of two flow paths for water through soil-biochar mixtures. One pathway is between the soil and biochar grains, and a second pathway is water moving through the biochar itself."

Barnes said the highly porous structure of biochar makes each of these pathways more torturous than the pathway that water would take through sand alone. Moreover, the surface chemistry of biochar -- both on external surfaces and inside pores -- is likely to promote absorption and further slow the movement of water.

"By adding our results to the growing body of literature, we show that when biochar is added to sand or other coarse-grained soils, there is a simultaneous decrease in bulk density and hydraulic conductivity, as opposed to the expected result of decreased bulk density correlated with increased hydraulic conductivity that has been observed for other soil types," Barnes said.

The study is the latest from Rice's interdisciplinary Biochar Research Group, which formed in the wake of Hurricane Ike in 2008 when the city of Houston called for ideas about how to get rid of an estimated 5.6 million cubic yards of fallen trees, broken branches and dead greenery left behind by the storm. The Rice Biochar Group won the $10,000 grand prize in the city's "Recycle Ike" contest and used the money to jump-start a wide-ranging research program that has since received support from the National Science Foundation, the Department of Energy, Rice's Faculty Initiative Fund, Rice's Shell Center for Sustainability and Rice's Institute of Bioscience and Bioengineering.

###

Study co-authors include co-first author Morgan Gallagher, a former Rice graduate student who is now a postdoctoral researcher at Rice and an associate in research at Duke University's Center for Global Change, and Rice graduate student Zuolin Liu.

High-resolution IMAGES are available for download at:

http://news.rice.edu/wp-content/uploads/2014/09/0924_BIOCHAR-b1.jpg

CAPTION: Biochar is ground charcoal that's added to soil to both boost crop yields and counter global climate change.

CREDIT: Jeff Fitlow/Rice University

http://news.rice.edu/wp-content/uploads/2014/09/0924_BIOCHAR-hydro-lg.jpg

CAPTION: Rebecca Barnes (front) and Morgan Gallagher conduct hydrology experiments at Rice University in 2013.

CREDIT: R. Barnes/Colorado College

http://news.rice.edu/wp-content/uploads/2014/09/0323_BIOCHAR-Barnes-lg.jpg

CAPTION: Rebecca Barnes

CREDIT: R. Barnes/Colorado College

http://news.rice.edu/wp-content/uploads/2014/09/0323_BIOCHAR-Masiello4-lg.jpg

CAPTION: Caroline Masiello

CREDIT: Jeff Fitlow/Rice University

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations via Twitter @RiceUNews

About Rice University

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,920 undergraduates and 2,567 graduate students, Rice's undergraduate student-to-faculty ratio is just over 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is highly ranked for best quality of life by the Princeton Review and for best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go here.

About Colorado College

Colorado College is a nationally prominent, four-year liberal arts college that was founded in Colorado Springs in 1874. The college operates on the innovative Block Plan, in which its approximately 2,000 undergraduate students study one course at a time in intensive 3½-week segments. The college also offers a Master of Arts degree in teaching. For more information, visit http://www.ColoradoCollege.edu

David Ruth | Eurek Alert!

More articles from Earth Sciences:

nachricht Hundreds of bubble streams link biology, seismology off Washington's coast
22.03.2019 | University of Washington

nachricht Atmospheric scientists reveal the effect of sea-ice loss on Arctic warming
11.03.2019 | Institute of Atmospheric Physics, Chinese Academy of Sciences

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>