Writer: Kathleen Davis Phillips, (979) 845-2872, ka-phillips@tamu.edu
Contact: Dr. Lloyd Hossner (979) 845-3814, Dr. Ed Colburn (979) 845-2935
COLLEGE STATION — A team of soil scientists who started digging up facts about lignite coal mining in the 1970s have unearthed the secrets to reclaiming disturbed land.
For their efforts in “minimizing the harmful environmental effects from surface mining of lignite coal,” five Texas A&M University research and extension scientists recently received the U.S. Department of Agriculture’s distinguished service award through the Cooperative State Research Service.
Lignite mining can be traumatic for the land as the topsoil and overburden (soil between the top and lignite layer) are shoveled out and stored in piles while the coal is extracted. Federal laws were passed in 1977 requiring surface mined land be returned to as good or better than its pre-mined condition.
The scientists began studying the problem in 1971 to determine how to best establish vegetation in soil that was returned after extracting the lignite, according to Dr. Lloyd Hossner, professor of soil chemistry.
“We found that one of the problems was that iron sulfides deep under the ground make sulfuric acid when brought to the surface,” Hossner said. The team determined that the iron sulfide minerals had to be separated from the surface soil to prevent contamination during the restoration process.
By understanding the response of the minerals in the soil, Hossner said, the scientists learned that the reaction could be prevented by deeply burying the material before acid had a chance to form.
Hossner said that as new problems with reclamation arose, additional experts were included in the research including Dr. Larry Wilding, soil morphology; Dr. Joe Dixon, soil mineralogy; and Dr. David Zuberer, soil microbiology.
The need for reclamation is vast in Texas, the sixth largest lignite coal producer in the nation. Getting the research findings applied required a comprehensive educational effort. That’s when Dr. Ed Colburn joined the team as a Texas Agricultural Extension Service soil management specialist to educate the lignite industry on ways to prepare and conduct mining for the best chance of reclamation.
According to the Texas Railroad Commission, more than 100,000 acres in Texas have surface mining permits, about 6,000 acres of which are disturbed annually for lignite extraction. Texas produces about 53 million tons of lignite a year. The problem with land reclamation is similar throughout other southern states where surface mining is conducted.
Colburn estimated that between 1977 and 1992 some 56,000 acres were permanently revegetated, including 54,760 acres mined during that time plus some land that had been mined prior to 1977.
“Now, as quickly as they can get on it after mining, the land is revegetated,” said Colburn. “And some work can be done while mining is in progress, often up to 150 feet from the edge of the mine.”
He said complete reclamation usually takes one or two years after mining.
“We’ve studied revegetating with forage grasses and legumes, field crops such as corn, sorghum and soybeans, trees and other crops that normally would not have been grown on these soils,” Hossner said. “Another discovery has been that the land has a lot more capability to produce crops than it would have prior to mining when the proper reclamation techniques are used.”
The advanced technology developed by the team is being used in Louisiana, Mississippi and Alabama. The research on acid formation in the soils also is being used in coal mining states and throughout the world, according to the USDA award documents. Their work has attracted more than $2.5 million in grants.
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