Energizing Marginal Lands
While it’s generally hypothesized that energy crop yields on marginal lands would be lower than if planted on prime agricultural lands, lower-value acres could still represent an opportunity to supplement biomass feedstock production. Current research by multiple organizations seeks to determine whether growing certain energy crops on marginal lands is productive, efficient and economic.
First-year yields from miscanthus plots on reclaimed mining lands in eastern Ohio show less-than-stellar results, but researchers say they don’t indicate an inability to produce meaningful biomass on those acres. “The first year is really insignificant,” says Rasto Ivanic, senior director of business development for Mendel Biotechnology Inc. The company is working with Ohio-based coal mining company Oxford Resource Partners on a pilot project growing Mendel’s proprietary miscanthus varieties on Oxford’s reclaimed lands. The trial will establish a baseline performance to conduct studies into the potential of growing perennial grass in the nutrient-poor soil. Reclaimed lands are those where the soil has been disturbed and then reapplied, mixing up the layers with rocks, mud, clay and hollows.
“It’s obvious that the performance of these plants early on in the disturbed lands is significantly lower than what we see in a more typical agricultural setting,” Ivanic says. “We would expect lower, more choppy performance in these areas.” Even so, he says the trial is performing quite well. “We certainly see a little bit less growth in these reclaimed lands, a little bit lower percentage of established plants than what we would observe in other situations but, by and large, looking at the first year of the trial data, we are happy with the way those trials established,” he says.
The big question, Ivanic says, is how does miscanthus grow below the surface on marginal lands? Does it establish a strong enough system to survive winter and accumulate nutrients to develop a thicker, stronger stand in the spring? “We don’t know yet,” he answers. “In a year, we’ll be much smarter.” Data collected from past research shows miscanthus might not need added nutrients to thrive, and some evidence suggests the plant can fix nitrogen from the air like a legume, Ivanic says. “Now that doesn’t mean that miscanthus may perform better on distressed lands, but for those lands that are nutritionally poor—either they’ve been overused or just don’t have enough nutrients—there is a hypothesis that miscanthus can, over time, improve that land,” he adds. But not all marginal lands will be candidates for such planting. “If I could venture a hypothesis, I would say there are certainly [marginal] lands that will be beyond reach.”
Growing energy crops on rocky, inconsistent soil with hollows and holes does represent new challenges and intricacies, sometimes requiring manual planting, as was the case at another of Mendel’s marginal plots in Indiana. “You either have a puddle of mud or you have a brick,” Ivanic says, adding that it will translate into an inconsistent stand. “It’s going to be much more varied than what you might expect on a traditional agricultural rotation.”
While those marginal lands may be able to provide meaningful yields after further research and improvements, the focus initially needs to be on agricultural lands in order for energy crops to be a regular part of the agricultural rotation, Ivanic says. “There certainly is a potential for marginal lands,” he says. “But I think we’d be shooting ourselves in the foot if we only focused on marginal lands.”
Mendel also has marginal land trials in West Virginia, but has a number of non-marginal acres planted west of the Mississippi River. “Because the hypothesis is to make this energy crop system economical, you will likely not end up planting in marginal land at the start,” Ivanic says. “Our trials focus on areas where we feel the economics and performance of the crop is most likely to be successful.” The company is experimenting with land on the outside fringes of the most productive agricultural lands, as well as former cottonwood acres in the South.
“Most of our trials are targeting those areas, and in most geographic areas you’ll find those acres that we would consider reasonable for an energy crop because they would represent marginal economics for corn or soy.”
The Meaning of Marginal
Besides soil nutrient content and productivity, economics are indeed a crucial determining factor in categorizing marginal lands. But the term can be confusing, according to Richard Hamilton, president and CEO of energy crop company Ceres Inc. “I don’t like using the word marginal,” he says. “It’s marginal for what?”
The word is often used generally to describe acres not used for producing food crops, he says. “I think that confuses the issue because at the end of the day, there’s no such thing as a nonfood acre. If you show me any acre in the world that can support photosynthetic life, I will grow you a human-digestible calorie.” Hamilton prefers the term low-rent land because all lands have a plethora of alternative uses, but factors such as drought, soil fertility and salt can make it difficult to get a high yield from traditional crops. “Economic rents determine what the highest and best value of the land will be,” he says, adding it’s unlikely that energy crops will be grown on high-yielding corn land because the economics dictate corn should be grown there.
Ceres is forging ahead with research into a salt-tolerant trait that enables energy crops such as switchgrass to grow in salt-damaged soil. Researchers discovered the useful property while screening for other agronomic traits and began to experiment with it, increasing the salt levels. The trait was still tolerant at salt concentrations equivalent to those of seawater, which are four times higher than concentration capabilities of any other salt-tolerant trait reported in scientific literature, Hamilton says.
The research is moving from greenhouse to field scale and is using a United States Agency for Internal Development grant to experiment with the trait in rice in India. “If those field results are positive, then of course it holds great benefit for food crop production,” Hamilton says. “[The trait] is simply illustrative of the point that low-rent acres like salt-damaged acres in southern Texas or Louisiana can be put back into valuable production in a way that reduces greenhouse gas production.”
Still, energy crop improvement is in its early stages and will undoubtedly grow exponentially, much like improvements to food crops such as corn, Hamilton says. “We cannot assume that yields will stay flat. We can’t look at it through the lens of what the yields are today, but we have to look at it through the potential of what we can accomplish with modern biology, and therefore, what might the yields be five and 10 years from now.”
Switchgrass and Sorghum
Ceres has a number of plots on marginal lands testing the viability of its commercialized switchgrass and high-biomass sorghum varieties, with no trait modifications in most areas, according to Frank Hardimon, director of sales for the company. Switchgrass has the natural and unique ability to grow on marginal soils because of its tremendous root system, he says. It is also a low-input crop, requiring smaller amounts of nitrogen, potassium and phosphorous than most crops, which makes it appealing for many farmers.
“We’ve got a tremendous ability in the U.S. to plant these crops,” Hardimon says. He adds that marginal lands don’t necessarily imply smaller yields of switchgrass because there are many different kinds of the crop. It generally fairs better, though, on southern marginal lands than northern because of the heat and moisture.
Sorghum, however, tends to produce smaller yields on marginal acres than it would on prime Midwest lands, but the crop has the advantage of being drought tolerant. The annual crop can also produce better yields in its first year than switchgrass can, at 15 dry tons per acre compared with switchgrass’s third-year maximum of 10, he says.
Hardimon agrees that planting energy crops on marginal lands can help increase yields for more biomass use, and incentives such as USDA’s Biomass Crop Assistance Program, which will issue matching payments to growers, will help spur farmer interest in planting on both nutrient-rich and -poor lands.
Pilot tests by companies such as Ceres and Mendel will help determine if and how much marginal land can be used for energy crop production, as well as whether it’s economical. “We’re in the stage now where we’re trying to establish what those economics would look like on different types of land, marginal and nonmarginal, and then we’ll go from there,” Ivanic says.
Author: Lisa Gibson
Associate Editor, Biomass Power & Thermal