by Randy Weckman

Las Vegas boasts “what happens here stays here.” In some ways, it's too bad that water isn't like that. With water, what happens upstream ends up downstream. That's why management practices that minimize untoward impacts all along a waterway are important. College of Agriculture researchers are discovering new ways to maintain the quality of water here—and elsewhere.

College of Agriculture forest hydrologist Chris Barton knows that beginning this spring and throughout the summer and fall, he'll be conducting research in Robinson Forest , the College's 11,000-acre maturing forest in Eastern Kentucky.

Barton said that because Robinson Forest hasn't been logged since the early 1900s, “we have a maturing forest that can serve as a great site to study the effects of logging on water quality as well as plant species composition and animal habitat.”

 

Chris Barton tests water quality in Robinson Forest.

 

 

 

 

He and his graduate students already have spent the last two years collecting benchmark data to assess the effects of logging on the forest's water supplies in anticipation of a major research project.

Starting this spring, several sites within the forest totalling about 1,000 acres will be harvested for timber. Barton will study the effects of various management practices now prescribed for logging. The research is important because current best management practices for logging in areas adjacent to streams are based on data collected in many other terrains, not Kentucky's.

Barton's research will evaluate whether the current prescriptions for logging in the Appalachians are the most effective in protecting habitat. On some stream banks he will use the currently recommended 55-foot buffer; on others he will cut that width in half; and on still others, he will double it.

“This research will provide the timber harvesting industry with better information on how much of these green zones of life need to be left to protect water supplies as well as plants and animal habitat,” Barton said.

A Big Idea That Works

“Mountaintop removal” can be fighting words in certain parts of Kentucky. The standard practice of leveling the mountaintop after coal extraction has left a bad taste in the mouths of some of those who rely on local drinking water. The reason is that iron, sulfate, and manganese sometimes move from the spoils into groundwater and streams.

A research team including Don Graves (forestry), Richard Warner and Carmen Agouridis (biosystems and agricultural engineering), and Chris Barton (forestry) has found a way to reduce the movement of iron, sulfate, and manganese into streams and, at the same time, return the mountains back to forest.

The concept is straightforward. Give trees what they need to thrive. Rather than leveling the spoils for pastureland—which usually results in high soil compaction—leave the soil nice and loose, and in little mounds. If you dump the spoil rather loosely onto the fill area, trees can sink their roots deep into the remains and grow.

 

Richard Warner's research is helping trees to grow as well as improve water.

 

 

Graves and Warner tried the technique on three sites in Eastern Kentucky. (Because this was a research project, they also had three sites that were conventionally filled with compacted spoils for a comparison.)

The difference between the two treatments was remarkable, and the response was quick. Trees grew quickly and robustly on the loose-dump site; some are now over 20 feet tall after just eight years. The sites with compacted spoils have a tree here and there, and those that are there look rather puny.

Warner also found, when he measured the seepage rate, that rainfall ran off the surface of the compacted spoil much faster than from the loose-dump sites.

“This points to one of the major advantages of the loose-spoil technique; that is, a large reduction in potential flooding,” he said.

As the forest grows, there will be high water usage by the trees, which should reduce the amount of iron, sulfate, and manganese that moves into streams.

Not only is the research of Warner and Graves reducing flooding and improving water quality in Eastern Kentucky, it also is a more economical method of reclaiming mine lands— about $1,200 cheaper per acre.

Kicking Nitrogen out of Soil

Agricultural engineer Steve Workman and agronomist Mark Coyne are researching the ability of plants and soil microbes in riparian areas (the banks of rivers, streams, and lakes) to transform fertilizer nitrogen into harmless nitrogen gas that becomes part of the air we breathe and to store carbon (which helps convert the nitrogen). “Free” carbon can bind with oxygen to form carbon dioxide, which has been linked to global warming.

Here's how the duo is conducting the research:

They dig 30-by-15-foot pits of soil that are three feet deep. The pits are lined with plastic and refilled with the soil. On each of these pits, one of three plant species is planted—a bamboo species of river cane or eastern gammagrass, both of which are native to Kentucky, or fescue grass, an interloper to the state.

They selected three types of plants because of their different rooting characteristics.

“This is important because water tables in riparian areas rise and fall seasonally. Different rooting depths may be associated with differing ability to convert nitrogen and store carbon,” Coyne said.

The scientists add a watery broth of fertilizer nitrogen at one end of each cell. Each cell is slightly tilted so that the liquid travels through the cell before it drains.

Workman and Coyne check the drainage for nitrogen and carbon and assess the different plants' uptake of nitrogen and carbon.

“After two years of data collection, it appears that the soil microbes transform nitrogen and carbon just as well with or without the plants, but that simply may be because the plants haven't yet established themselves enough to provide much help in converting the nitrogen,” Workman said.

Steve Workman walks a project designed to study the
effects of vegetation on water quality.

 

“Over time, we may find that plants enhance the transformation of nitrogen and the storing of carbon,” he said.

Their research findings may well help farmers and urban planners in the future make better plant selections in riparian zones to minimize—or even eliminate—the migration of soil nutrients into waterways.

Wetlands Get Better With Age

Elisa D'Angelo, soil biochemist, is researching this question: Can newly constructed wetlands sequester nitrogen and phosphorus as well as natural, forested ones? (Constructed wetlands are federally mandated when natural wetlands have been destroyed, such as those destroyed by coal extraction.)

In collaboration with plant and soils scientist Anastasios Karathanasis and Jerry Sparks with the Army Corps of Engineers, D'Angelo's research compares the nitrogen and phosphorus removal capacities of nearly two dozen forested wetlands of different ages in Western Kentucky

“Usually, researchers take a black box approach to determine an ecosystem's capacity to retain nutrients. We studied the underlying biogeochemical mechanisms by which wetlands sequester pollutants and protect water quality,” D'Angelo said.

As the team predicted, the wetlands' capacity to support anaerobic microbial processes, such as nitrate removal, depended on the soil's water-holding capacity, which in turn was determined by the amount and chemical composition of vegetation and soil organic matter.

“Molecular analysis of soil microbial communities showed clear shifts from aerobic to anaerobic populations in the organic matter-enriched older ecosystems. This is the first time that molecular microbial analytical tools have been used to assess wetland ecosystem functioning,” she said.

What the team didn't expect to find, but did, was that phosphorus retention was strongly affected by soil organic matter, through its influence on aluminum and iron chemistry.

“Soils from older forested wetlands had nearly four times more organically bound aluminum and iron oxides and phosphorus sequestration capacity than did younger sites,” D'Angelo said.

Based on the team's research, it will take more than a century for a constructed wetland to achieve the same capacity to function as well as a naturally occurring forested wetland.

“This research provides a clear, science-based method for identifying wetland mitigation sites and helps determine how large those sites need to be to protect water quality,” she said.

 

 

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