Giant Plant May Help Recovery Of Mine Lands

A WVU researcher is studying a plant that can help restore surface mine lands by creating missing topsoil and capturing carbon out of the air and storing it underground. The above ground plants can also be used as biomass which can be turned into biofuels or even particle board. 

News Director Eric Douglas spoke with Jennifer Kane, a postdoctoral student in plant and soil sciences from the WVU Davis College of Agriculture, Natural Resources and Design. She is studying the plant Miscanthus (Miscanthus × giganteus). She grew up in Raleigh County and has first-hand knowledge of the abandoned mine lands she is looking to improve. 

This interview has been lightly edited for clarity. 

Douglas: We’ve seen stories of people getting grants, we’ve seen efforts to plant on former reclaimed coal mine lands or even abandoned mine lands, to restore them with mixed success. And it’s just not worked because the soil is not topsoil anymore. It’s just not got the nutrients in it, so nothing’s growing real well. This kind of intrigues me as something that is actually growing and can actually serve a purpose on coal mine lands. 

Kane: My family specifically, we’re kind of a transplant, my parent’s generation moved here. So I don’t have a long line of multiple generations but certainly I went to high school in Coal City and went to school with many people whose family spent five generations in the mines. We would ride four wheelers on old mines that were pre-SMACRA. They weren’t reclaimed at all, some hazardous conditions and obviously, things weren’t going well. And what I would say about Miscanthus is we’ve been testing it on varying mine disturbance across a spectrum. Anywhere from it’s really bad. 

Douglas: SMACRA is? 

Kane: Surface Mining Reclamation and Control Act of 1977.

Douglas: Post 1977, the mining industry had to put money into a fund to help reclaim mine lands. It’s not near enough, but that’s a different story.

Kane: Yeah, some level of accountability with some basic reclamation requirements.

Douglas: Before 1977, they often just walked away.

Kane: We have one site like that, that was a pre-77 surface mine. It was just left as bare rock unreclaimed. The interesting thing, we do see lower yields of Miscanthus on those lands, but it’s still certainly alive and well. The two purposes of Miscanthus in our minds are maybe one day, we could use it for energy or materials, but it also literally builds soil under it. That’s a really great thing about it is that even on these really disturbed sites where the yields are pretty low, and it may not be viable for really high industrial use, it’s making the soil better under it. 

Douglas: This has a pretty significant root system underground as well. This is one of those that reaches down four or five feet, right?

Kane: Here they are four or five feet , yes, but some places out in the Midwest that we kind of watch their research and are jealous of because they have these beautiful deep soils, they’ll find roots 9 to 10 feet. Here, I would say four or five feet is a good estimate but that’s something we’re looking into. We’re looking into how much root biomass there is, how deep it goes. 

Douglas: That stabilizes the soil and then as it grows and decomposes, adding nutrients into the soil. 

Kane:  It certainly helps with things like hydrology, and you don’t see these lands kind of washing away, indirect effects on other indirect consequences of mining, like the devastating floods we see all over the state. 

Douglas: Describe for me what grows above land. This is such an interesting plant that it’s doing all these great things for the soil. But you’re also talking about harvesting it and using it for biofuels.

Kane: There’s a lot of interesting uses. We in the U.S. are not on the forefront, I wouldn’t say, of bioenergy technology, but some places in Europe are using Miscanthus. You can use it for more traditional bioenergy, cellulosic ethanol production, where you are fermenting it and it ends up as ethanol, but that may not necessarily be the best use of it. I mean, people have pellet stoves and things like that. It can be pelletized and burned similar to how wood is used for heat and energy. Also, there’s an interesting company, again in Europe somewhere I believe, and they’re actually making building material like particle board out of Miscanthus. It’s not a good forage grass, unfortunately, but it is really strong and tough. If you walk through a field of it, you’re all scratched up and in pain. It’s a strong plant. It has a really high photosynthetic efficiency, so for how well it can produce in terms of biomass, it uses relatively little water and nutrients.

Douglas: Is this like, three, four feet tall? 

Kane: Fifteen or 16 feet. 

Douglas:  You said the pre-77 plot is probably less than that. 

Kane:  It’s an interesting thing that happens on those plots. We’re seeing some tradeoffs in height versus less stems that are taller versus more stems. So it’s thinner, if that makes sense. And we see through the roots, you dig down four inches, and it’s refuse. It’s coal. It’s busted up rock, and there’s chunks of coal down there. We pull all kinds of stuff out of there. The roots adapt, and the plant adapts to survive, resulting in less total biomass. 

But again, we’re seeing an increase in soil organic matter. You can even feel it if you just look at the soil five years ago, when we planted them, versus now you can see we’re actually getting a topsoil layer now.

Douglas: What’s the long term goal of your research?

Kane: Essentially, the bacteria and fungi in the soil are living, they’re decomposing all of this dead plant matter and root matter that comes into the soil. And that decomposition results in some CO2 production as they use enzymes to break down the plant material. But they also take a lot of those carbon and nutrients into their own biomass. So think of bacterial cells, they need that stuff to grow, and live themselves. Once they take it into their biomass, it can stay in the soil through a couple different mechanisms. It can be actually stabilized for long periods of time, and we see that that’s favorable in terms of how much CO2 ends up in the atmosphere and continues to warm our planet.

Douglas: This plant is a net collector of CO2? 

Kane: I wouldn’t go so far as to say our plots are a total net positive, but we are seeing increases in soil carbon. In order to know that, we would have to do a landscape level carbon stock analysis, which we may do someday. But some people have done it and they’ve accounted for all the CO2 from all the cultivation — all of the machines they bring in, all of the production once they harvest it – and they found that it’s still more carbon in the soil than was released.

Douglas: If you’re harvesting these plants and then using them in something, doesn’t that release some level of CO2 as well?

Kane: Absolutely. Depending on what you do with it, I mean, obviously burning it will produce CO2, and I’m not sure if it’s a net positive in that regard. But it’s certainly better than something like fossil fuels where there’s no offset. And it’s renewable on a very short timescale.

Douglas: How long does it take to get 15 foot tall plants?

Kane: By year one and year two there is a little bit less yield, but in year 3, 4, 5, we were getting into the 10 feet 12 feet. I would say between years three and five is the standard for when you can expect the most biomass.

Douglas: Is there anything we haven’t discussed?

Kane: We’ve done several studies since 2019 on the whole system. My study specifically has to do with the roots and how roots interact with microbes at that very small scale because we have evidence that the Miscanthus roots may produce more roots or less roots or their tissue chemistry might change, and that can also impact the soil carbon cycle.

Douglas: How many plots are you working? 

Kane: In Morgantown, we have 64 plots. They’re not as big as you might think, they’re like five meters by five meters. Another key piece of this project is we’re testing how different common agricultural practices like fertilization impacts these dynamics. If the plant is relying on the microbiome to get nutrients from the soil, and the atmosphere in some cases, and if we add in fertilizer, does that disrupt that relationship? We’re testing those things and trying to understand what type of factors disrupt that plant-microbial relationship. We also have some studies going on with drought, and how when humans come in and change things, or when climate change changes things, what is that going to mean for the whole system?

Douglas: It’d be interesting to see what it does over the long term on reclaimed land. 

Kane: A collaborator of mine, Jeff Skousen, who’s the reclamation specialist here at WVU, has some plots that are 10 to 15 years old on places like the Hobet mine site. These are bigger reclamation sites, so there’s work there, but certainly not enough.