Nav: Home

Study finds declining sulfur levels

May 09, 2016

  • With the move from burning coal to natural gas and low-sulfur coal and an increase in the use of scrubbers, only about 25 percent as much atmospheric sulfur is available today, compared to 40 years ago.

  • Sulfur balances in agricultural fields are now negative, with more removed each year in crop harvests and leaching than is added from fertilizers and deposition.

  • Fields with tile drainage move sulfate quickly to surface waters, contributing to the low levels in the soil.

  • Rivers in agricultural watersheds have declining sulfate concentrations, a direct response to declining atmospheric deposition.

  • Farmers may need to apply sulfur fertilizer at some point in the future, particularly on fields with less soil organic matter.

URBANA, Ill. - Air pollution legislation to control fossil fuel emissions and the associated acid rain has worked - perhaps leading to the need for sulfur fertilizers for crop production. A University of Illinois study drawing from over 20 years of data shows that sulfur levels in Midwest watersheds and rivers have steadily declined, so much so that farmers may need to consider applying sulfur in the not too distant future.

"We don't think there are actual sulfur deficiencies yet, but clearly more sulfur is coming out of the soil and water than what is going in," says U of I biogeochemist Mark David. "As the Clean Air Act and amendments have taken effect there has been a reduction in sulfur emissions from coal combustion, so that the amount of atmospheric sulfur deposited each year is only 25 percent of what it used to be. At some point, farmers are going to have to fertilize with sulfur."

David says farmers whose fields have fine-textured soils that are high in organic matter have less of a concern. "For many, it could be 10 or 20 years from now, but for some, particularly those farming on poorer soils, it'll be sooner. Farmers whose fields have poorer soil or notice a yield reduction may want to have their soil tested for sulfate. If it registers low, they can consider applying fertilizer."

David explains that sulfur in soil comes from two main sources. It's in the air from fossil fuel combustion and in groundwater where water has come in contact with coal or pyrite seams. It comes out of the soil through tile-drained fields and it is taken up into plants as they grow and are then harvested. Most fields in Illinois do not receive fertilizers containing sulfur. Some in the Embarras and Kaskaskia watersheds apply ammonium sulfate, which adds not just nitrogen, but also sulfur.

In their study, David and his team analyzed data from three rivers in east-central Illinois at times when the flow was high and low from the field drainage tiles and the rivers. Sulfate concentrations were greatest in the Salt Fork River, followed by the Embarras, and then the Kaskaskia Rivers.

"As we go from northeast to southwest across this part of Illinois, the sulfate that we think is from groundwater near coal seams, decreases. In the Tuscola and Atwood areas, we don't think there are any groundwater sulfate inputs. When we looked at a whole variety of fields with tile drainage systems, we found that some had very low sulfate concentrations - just a few milligrams per liter. One farm in our study had applied bed ash from a power plant. We saw high concentrations of sulfate in that field. There's no doubt that it boosted the level of sulfur. But over the next three or four years most of it had washed out through the tile system," co-author and U of I agronomist Lowell Gentry says.

The long-term nature of the study allowed the team to do watershed balances and look at the inputs and outputs of the sulfur "budget" for the area.

"That balance is negative, with greater outputs from harvest and leaching, than inputs from atmospheric deposition and fertilizers, so what is missing is coming from the soil. There is a lot of sulfur in soil in organic forms and that's being slowly depleted. At some point, there won't be enough to keep up with what the crop needs. That's when farmers will need to add fertilizer," Gentry says.

David began his career in the 1980s studying the effects of acid rain - a main ingredient of which is sulfur. "Back then no one ever thought about fertilizing with sulfur because there was always plenty of atmospheric sulfur available from burning coal."

The samples David collected over the past two decades were primarily used to track nitrates that enter the rivers via drainage tiles in agricultural fields, and eventually reach the Gulf of Mexico. He says that unlike nitrate, "sulfate is not a problem in Midwestern streams and rivers. It's not like other chemicals that cause problems downstream and in the Gulf."

David believes that this is the first study looking at long-term trends in sulfur in agricultural areas. "Most of the studies about atmospheric deposition in sulfur have been in forested watersheds in the northeast where lakes were acidified, such as in the Adirondack Mountains in New York and in streams in the Appalachian Mountains, areas that were sensitive to acid rain. Sulfate is more of a problem in the northeast in forest soils," he says.
-end-
"Riverine response of sulfate to declining atmospheric sulfur deposition in agricultural watersheds" is published in the Journal of Environmental Quality and is available online through open access at https://dl.sciencesocieties.org/publications/jeq/pdfs/0/0/jeq2015.12.0613. It was written by Mark B. David, Lowell E. Gentry, and Corey A. Mitchell.

The work is based on research partially supported by the National Institute of Food and Agriculture, USDA, under Agreement No. 2011-039568-31127, the National Atmospheric Deposition Program through HATCH Project ILLU-875-935, and the Energy Biosciences Institute.

University of Illinois College of Agricultural, Consumer and Environmental Sciences

Related Acid Rain Articles:

Jeddah gets caught in the rain
Understanding how storms unleash more rain over cities in the desert could help water security in Saudi Arabia.
Forest soils recovering from effects of acid rain
Study shows improvement of soils and streams in the southern Appalachians.
More rain and less snow means increased flood risk
By analyzing more than two decades of data in the western US, scientists have shown that flood sizes increase exponentially as a higher fraction of precipitation falls as rain, offering insight into how flood risks may change in a warming world with less snow.
Biochar: A better start to rain forest restoration
An indigenous farming technique that's been around for thousands of years provides the basis for restoring rain forests stripped clear of trees by gold mining and other threats.
Plants use more water in soils leached by acid rain, West Virginia forest study shows
In one of the first long-term studies to explore how changing soils have impacted plant water uptake, researchers report that plants in soil leached by polluted rain drink more water.
Downpours of torrential rain more frequent with global warming
The number of extreme downpours increased steadily between 1964 and 2013 -- a period when global warming also intensified, according to research published in the journal Water Resources Research.
Was the restaurant really that bad -- Or was it just the rain?
There are a few things that will result in poor customer reviews of a restaurant: bad service, bad food -- and bad weather.
Unexpected rain on sun links two solar mysteries
Researchers find rain on the sun in an unexpected place.
How does the Amazon rain forest cope with drought?
The Amazon rain forest isn't necessarily a place that many would associate with a drought, yet prolonged dry spells are projected to become more prevalent and severe because of climate change.
First detection of rain over the ocean by navigation satellites
In order to analyse climate change or provide information about natural hazards, it is important to gather knowledge about the rain.
More Acid Rain News and Acid Rain Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Clint Smith
The killing of George Floyd by a police officer has sparked massive protests nationwide. This hour, writer and scholar Clint Smith reflects on this moment, through conversation, letters, and poetry.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Nina
Producer Tracie Hunte stumbled into a duet between Nina Simone and the sounds of protest outside her apartment. Then she discovered a performance by Nina on April 7, 1968 - three days after the assassination of Dr. Martin Luther King Jr. Tracie talks about what Nina's music, born during another time when our country was facing questions that seemed to have no answer, meant then and why it still resonates today.  Listen to Nina's brother, Samuel Waymon, talk about that April 7th concert here.