URBANA, Ill. – Farming crops with crushed rocks could help to improve global food security and capture CO2 from the atmosphere, a new study has found.
The pioneering research by scientists at the University of Illinois, together with U.S. and international colleagues, suggests that adding fast-reacting silicate rocks to croplands could capture CO2 and give increased protection from pests and diseases while restoring soil structure and fertility.
Stephen Long, Gutgsell Endowed University Professor of Crop Sciences and Plant Biology at U of I and co-author of the study, provides context: “Global warming is a problem that affects everyone on the planet. Scientists generally have done a poor job of getting across the point that the world must reduce emissions of greenhouse gases from fossil fuels and combine this with strategies for extracting carbon dioxide from the atmosphere to avoid a climate catastrophe.”
David Beerling, Director of the Leverhulme Centre for Climate Change Mitigation at the University of Sheffield and lead author of the research, explains the project: “Human societies have long known that volcanic plains are fertile, ideal places for growing crops without adverse human health effects, but until now there has been little consideration for how adding further rocks to soils might capture carbon.
“This study could transform how we think about managing our croplands for climate, food, and soil security. It helps move the debate forward for an under-researched strategy of CO2 removal from the atmosphere - enhanced rock weathering - and highlights supplementary benefits for food and soils. Adopting strategies like this new research could have a massive impact and be adopted rapidly.”
The research, published today (19 February 2018) in Nature Plants, examined amending soils with abundant crushed silicate rocks, like basalt, left over from ancient volcanic eruptions. As these minute rock grains dissolve chemically in soils, they take up carbon dioxide and release plant-essential nutrients.
Critically, enhanced rock weathering works together with existing managed croplands. Unlike other carbon removal strategies being considered, it doesn’t compete for land used to grow food or increase the demand for fresh water. Other benefits include reducing the usage of agricultural fertilizers and pesticides, lowering the cost of food production, increasing the profitability of farms and reducing the barriers to uptake by the agricultural sector.
Crushed silicate rocks could be applied to any soils, but arable land is the most obvious since it is worked and planted annually. It covers approximately 10 percent of the global land area.
Farmers already apply crushed rock in the form of limestone to reverse acidification of soils caused by farming practices, including the use of fertilizers. Managed crops, therefore, have the logistical infrastructure, such as road networks and machinery, needed to undertake this approach at scale. These considerations could make it straightforward to adopt.
“Our proposal is that changing the type of rock, and increasing the application rate, would do the same job as applying crushed limestone but help capture CO2 from the atmosphere, storing it in soils and eventually the oceans,” Long says.
James Hansen from the Earth Institute at Columbia University and co-author of the work, adds, “Strategies for taking CO2 out of the atmosphere are now on the research agenda and we need realistic assessment of these strategies, what they might be able to deliver, and what the challenges are.”
The article, “Farming with crops and rocks to address global climate, food and soil security,” is published in Nature Plants. Researchers participated from U of I, University of Sheffield, Lancaster University, James Cook University, Potsdam Institute for Climate Impact Research, University of California, Santa Cruz, and Columbia University. The work was supported by the Leverhulme Trust.
Biochar could replace unsustainable peat moss in greenhouse industry
URBANA, Ill. – Plant lovers are familiar with peat moss as the major component of potting mix, but harvest of the material is becoming unsustainable. Not only is peat being removed faster than it can re-form, its use in potting mix contributes to the release of carbon dioxide into the atmosphere.
“Peat bogs naturally store carbon. When peat moss is harvested, there’s a transfer of a global carbon sink into a net source. That’s because within a couple growing seasons, most of the peat moss from the potting mix is either mineralized by microbes or thrown out and decomposed. Either way, carbon dioxide is released,” says Andrew Margenot, assistant professor in the Department of Crop Sciences.
In a recent study, Margenot and colleagues from the University of California, Davis investigated a material called biochar as an alternative to peat moss in potting mix. Similar to charcoal, biochar is produced through a process called pyrolysis, or heating to high temperatures in the absence of oxygen. And like charcoal, it can be derived from virtually any organic substance.
“In our study, we used one made from softwoods from selective logging. But biochars can be made from corn stover, switchgrass, and lots of other organic waste products,” Margenot says. “Biochar could even be made from a greenhouse operation’s own waste, if there are trimmings from plants or old peat moss.” Margenot emphasizes that ‘biochar’ refers to a very broad class of material that can vary greatly in its properties depending on the pyrolysis temperature and the feedstock used.
When organic material decomposes naturally, the process releases carbon dioxide. But biochar decomposes very slowly – potentially on the order of centuries – so when organic material is turned into biochar, the carbon is essentially sequestered and can’t escape back into the atmosphere.
But how well does it work in potting mix? To find out, Margenot and his team grew marigolds from seed to flower in a number of experimental potting mixtures that replaced peat moss with an increasing proportion of commercially available softwood biochar.
In the biochar mixtures, pH soared. “The ones with lots of biochar had a pH up to 10.9, which is ridiculous for trying to grow things,” Margenot says. But this wasn’t unexpected for the type of biochar the researchers used.
Marigolds grew and flowered just fine, even when biochar replaced all of the peat moss in the potting mix. However, for plants growing with high concentrations of biochar, the early stages were a struggle.
“You could see that the plants took a hit in the early stages of growth – the first two to three weeks. They were shorter and had less chlorophyll, indicative of a nitrogen deficiency, which you’d expect at such a high pH. But these plants caught up by the end. By flowering stage, there was no negative effect of biochar versus peat moss,” Margenot says.
Not only did the plants suffer no long-lasting negative effects of the biochar, the pH in those pots neutralized by the end of the study. Margenot thinks this could have been due to a natural process of ion exchange between plant roots and potting mix, naturally occurring carbonates in the irrigation water, or the use of industry-standard fertigation – irrigation with low levels of dissolved nutrient ions such as nitrate and phosphate – in the experiment.
Although he only tested one type of biochar in one type of plant, Margenot is optimistic about the promise of biochar in nursery applications. “Because we used a softwood biochar known for its high pH, we really tested the worst case scenario. If it could work in this case, it could probably work with others.”
The article, “Substitution of peat moss with softwood biochar for soil-free marigold growth,” is published in Industrial Crops and Products. Margenot’s co-authors, all from UC Davis, include Deirdre Griffin, Barbara Alves, Devin Rippner, Chongyang Li, and Sanjai Parikh.
Phosphate rock an effective fertilizer in Kenya
URBANA, Ill. – Farming in western Kenya is challenging, to put it mildly. Although farmers can cycle two full crops in a single year, extremely poor soils and expensive traditional fertilizers, such as triple superphosphate (TSP), keep yields low. But results of a new University of Illinois study offer Kenyan farmers hope in the form of phosphate rock.
“Phosphate rock matches or slightly outperforms triple superphosphate if you’re looking at traditional agronomic assessments of soil phosphorus. But if you look at the benefits in terms of soil biology and health, phosphate rock skyrockets ahead of TSP,” says Andrew Margenot, assistant professor in the Department of Crop Sciences at U of I and lead author on the study.
Margenot and his team, which includes researchers from the University of California, Davis and the International Center for Tropical Agriculture (CIAT) in Nairobi, investigated the two phosphorus fertilizers in a long-term field trial on a typical Kenyan smallholder farm.
Triple superphosphate, which is about 45 percent phosphorus, must be imported from Moroccan mines. The fertilizer is highly soluble in the acidic, iron-rich soils typical of the region, but it presents several problems.
“It’s often not possible for farmers to afford the amount of phosphorus that’s recommended if you buy it in the form of imported TSP,” Margenot explains. “Plus, the iron in these soils combined with the low pH will bind up and immobilize the phosphorus in TSP. So you just wasted a pretty expensive investment.”
Phosphate rock, a fertilizer with only 8 to 12 percent phosphorus, is not only inexpensive, it is naturally suited for use in acidic soils.
“It’s the same mineral that our teeth and bones are made out of: calcium phosphate. For the same reason that acidic soda degrades your teeth, phosphate rock will dissolve best and be most useful as a fertilizer in low pH soils,” Margenot says.
In the study, the researchers applied TSP, phosphate rock, or no additional fertilizer to fields planted in a corn-bean rotation for a total of 13 cropping seasons. At the conclusion of the study, the team collected soil and measured crop-available phosphorus and the amount that was bound to iron.
In addition, the team also measured the amount of phosphorus that ended up in the soil microbial community. “The thinking is that microbes are able to outcompete geochemical sinks for phosphorus,” Margenot says. “The microbe can dart in and siphon up the pulse of phosphorus before it’s fixed forever by the iron. As microbial cells die, they free up their phosphorus, giving plant roots an opportunity to take it up.”
Traditional measures of crop-available phosphorus were similar for TSP and phosphate rock, but about 33 percent more phosphorus was bound to iron, and thus unavailable to crops, in TSP-fertilized plots. Impressively, 299 percent more phosphorus was present in the microbial pool in soils fertilized with phosphate rock.
“Phosphate rock is a form of slow-release fertilizer. TSP is a flood,” Margenot says. “There’s too much at once, it’s like trying to drink from a firehose. It’s too much for the microbes or the plant to take up, and so most of it just gets locked up by soil minerals forever.”
Yield effects of the fertilizers were reported in a companion study, which indicated that phosphate rock matched and, in some cases, outperformed TSP. Margenot says that’s partially due to the greater availability of phosphorus, but it’s also due to the fact that phosphate rock lowers acidity and provides additional nutrients – magnesium and calcium – to the soil and, ultimately, crops.
The article, “Biological P cycling is influenced by the form of P fertilizer in an Oxisol,” is published in Biology and Fertility of Soils. Margenot’s co-authors include Rolf Sommer and John Mukalama of CIAT and Sanjai Parikh of UC Davis.
Illinois researchers contribute to publicly accessible agronomy database
URBANA, Ill. – Data from the USDA-funded Sustainable Corn Coordinated Agricultural Project, which includes contributions from University of Illinois scientists, are now publicly available at https://datateam.agron.iastate.edu/cscap/. Comprising data from five years and 30 field research sites in the Midwest, it has been called one of the most comprehensive agricultural datasets ever to be published.
The research was funded from 2011-17 with a $20 million USDA National Institute of Food and Agriculture grant. The research included nine states, 11 institutions and a 140-member team, which was led by Lois Wright Morton and Lori Abendroth from Iowa State University, and included U of I researchers Maria Villamil and Emerson Nafziger, both in the Department of Crop Sciences.
“The team focused on management practices that could build resiliency to weather variability while maintaining crop yields and reducing negative environmental impacts,” Abendroth says. “It was our goal to make the data available to other scientists in a collaborative effort to advance our understanding of the interactions between the crops we grow, local soils, changing climate, and management decisions.”
The research areas included agronomy, soil science, greenhouse gas, water quality, drainage, and entomology. Data was collected at different frequencies ranging from yearly to sensor-based measurements collected in 15-minute intervals.
The U of I portion of the project was conducted at two western Illinois sites where Nafziger established crop rotation and tillage studies in the mid-1990s. “These studies have produced valuable data on long-term effects of crop rotation compared to continuous corn and soybean, and on how tillage affects yield and yield stability within different crops and rotations,” Nafziger says.
Villamil and her team focused on soil factors associated with different crop rotation cycles, including soil as a source of greenhouse gases. “We found that crop rotation, as opposed to continuous corn, helps to lower greenhouse gas emissions, and also helps to boost the yields for each cash crop,” says Gevan Behnke, graduate student in crop sciences at U of I and member of Villamil’s research team.
Nafziger adds that the use of nitrogen fertilizer on corn is the major factor in greenhouse gas emissions, so finding more emissions with continuous corn was not unexpected. “The major practical drawback for continuous corn in the experiment was that it yielded less than corn in rotation with other crops, and so was less profitable,” he says.
Standardized protocols were developed, as well as standards regarding data structuring and consistency for end-users. A data dictionary describes the measurements taken along with detailed field management data and notes to help users properly interpret the data. “This real-world data can be used in classroom exercises to better understand the responses and relationships inherent in agriculture. In addition, data can be used to train students in data sciences including visualization, analysis and interpretation,” Abendroth says.
“It’s public data; anyone can use it. I’m very proud of having been part of that effort,” Villamil says.
The team posted the data to the USDA National Ag Library Ag Data Commons, which is a long-term repository and provides additional access to the data. Teams receiving USDA-NIFA funding are required to make data publicly available once a project has ended. The Sustainable Corn CAP team encourages others to use the data to generate added value for research applications and educational purposes.
The Sustainable Corn CAP was a transdisciplinary team funded by the United States Department of Agriculture, National Institute of Food and Agriculture (USDA-NIFA, Award No. 2011-68002-30190).
Nickols-Richardson named Interim Associate Dean and Director of Extension
URBANA, Ill. – Shelly Nickols-Richardson has been named Interim Associate Dean and Director of Extension within the College of Agricultural, Consumer and Environmental Sciences (ACES) at the University of Illinois.
“Dr. Nickols-Richardson brings a tremendous amount of administrative leadership experience to this role, which will serve well as she works closely with all of us to evolve the Extension enterprise to the next level of excellence,” says Kim Kidwell, dean of the College of ACES.
In addition to serving as the head of the Department of Food Science and Human Nutrition (FSHN) for the past five years, Dr. Nickols-Richardson served as a member of the Extension 3.0 Task Force, which familiarized her with many of the opportunities and challenges Extension is facing. As the head of FSHN, she also had the opportunity to work with Extension faculty and staff on a regular basis.
“I consider Dr. Nickols-Richardson to be the ideal person to facilitate the implementation of the recommendations from the Extension 3.0 Task Force, and to create cohesion between Extension and the College of ACES based on the experience, perspective, and wisdom she brings to the position,” Kidwell says. “We will partner closely with college and Extension personnel to achieve this goal. It is imperative for our long-term success and sustainability that we frame an exciting vision that will allow us as a collective to manifest the land-grant mission that means so much to so many.”
While Nickols-Richardson is serving in this interim role, Nicki Engeseth, a professor in the Department of Food Science and Human Nutrition, has agreed to serve as the acting department head of FSHN. Having served in the interim head role several years ago, Engeseth brings experience and a deep understanding of the department to this role. Nickols-Richardson and Engeseth will assume their new duties and responsibilities on March 1.
Nickols-Richardson will succeed George Czapar, who will be retiring on March 1 as Associate Dean and Director of Illinois Extension. Czapar has served in this role for the past five years, activating the reorganization of Extension in an extremely challenging budget climate.
“Czapar’s dedication, compassion, and commitment to Extension and 4-H are unwavering,” Kidwell says. “The persistence and resiliency with which he has fought for the cause and has supported his personnel is truly impressive.”
U of I Extension receives grant to reduce nutrient loss in waterways
URBANA, Ill. - University of Illinois Extension has received a five-year, $1.5 million grant from the Illinois Environmental Protection Agency to help farmers and landowners reduce nutrient loss into Illinois waterways.
Extension will use the award to hire two watershed coordinators, who will work in high priority areas and help producers implement best management practices identified in the Illinois Nutrient Loss Reduction Strategy.
“Creating a strategy that addressed the concerns of everyone affected was a tremendous effort,” says Extension Director George Czapar. “What’s exciting about this grant is that now Extension has more capacity to help with implementation and making that vision happen on the ground.”
The watershed coordinators will focus on four high priority Illinois watersheds beginning in early 2018. A coordinator in the Embarras River and Little Wabash River watersheds will work closely with farmers to reduce nutrient loss, with an emphasis on phosphorus. In the Lower Rock River and Mississippi North Central River watersheds of northwestern Illinois, a coordinator will work to reduce nutrient loss, with an emphasis on nitrogen.
“We are excited to partner with University of Illinois Extension on this project. The watershed coordinators will play a key role in implementing the Illinois Nutrient Reduction Strategy by providing outreach and technical assistance to farmers and stakeholders in select priority watersheds,” says Illinois EPA Director Alec Messina. “This is yet another example of our Agency’s commitment to assist the agricultural community in reducing nutrient loss and improving water quality through voluntary efforts.”
Members of the agricultural community have already been heavily involved in nutrient loss education, reaching nearly 39,000 people at agricultural outreach events in 2016. According to the USDA, 70 percent of Illinois farmers were aware of NLRS conservation practices in 2016.
The grant to Extension also provides funding for an agricultural water quality science team composed of researchers from the University of Illinois College of Agricultural, Consumer and Environmental Sciences. The team will provide technical support and serve as a university resource to help develop new approaches for protecting water quality, and include faculty Laura Christianson, Reid Christianson, Cameron Pittelkow, and Maria Villamil in the Department of Crop Sciences; Jonathan Coppess in the Department of Agricultural and Consumer Economics; Paul Davidson in the Department of Agricultural and Biological Engineering; and Suzanne Bissonnette, assistant dean of Agriculture and Natural Resources in Extension.
Illinois EPA’s NLRS Coordinator, Trevor Sample, says, “Being connected to the scientists on this team is important. We want the watershed coordinators to not only provide outreach and education, but also serve as technical advisors on practices like cover crops and bioreactors.”
Study offers new tools to improve strategies for reducing nutrient runoff into Mississippi River
URBANA, Ill. – Every summer, the Gulf of Mexico is flooded with excess nitrogen and phosphorus from wastewater treatment plants and farm fields along the Mississippi River basin. And every summer, those nutrients create a “dead zone” in the Gulf. To address the issue, the U.S. Environmental Protection Agency formed a task force and required 12 states to develop strategies to reduce agricultural runoff.
According to researchers at the University of Illinois, the strategies show promise, and leave room for the addition of certain practical elements that could help decision makers choose specific conservation practices to adopt or avoid. In a new study, the researchers examine nutrient loss reduction strategies from three upper Midwestern states to help fill the gap.
The three state strategies analyzed in the study, Illinois, Iowa, and Minnesota, included science-based assessments of various conservation practices: things like cover crops, conservation tillage, bioreactors, modifications to nitrogen application rate, and more.
“We assessed the ability of each conservation practice to be stacked or layered with others and the ability to track the implementation of each practice. This gave us some very practical information that could be used to increase adoption by focusing on those activities that are affordable, easily tracked, and effective at reducing nitrogen and phosphorus runoff. Being able to track our efforts will also aid state and federal efforts in monitoring progress towards Gulf of Mexico hypoxia goals,” says Reid Christianson, lead author on the study and research assistant professor in the Department of Crop Sciences at U of I.
The researchers first compared how the three states rated the same practices in terms of their effectiveness, to come up with a consensus figure. For the most part, the ratings were similar across states. But a couple of practices stood out.
“Iowa and Illinois have very similar numbers on the cover crop front. But it’s much colder in Minnesota, and they have a hard time getting cover crop seeds to germinate after corn and soybeans have been harvested,” Reid says.
Woodchip bioreactors, an edge-of-field practice, were also ranked differently in the three states. The large trenches are typically filled with woodchips, housing microbes that consume excess nitrogen from drainage water. In this case, the differences were in sizing and design methodology in the three states.
Laura Christianson, co-author on the study and assistant professor in crop sciences, says, “Some practices, like cover crops, actually work differently north to south, but the other reason numbers varied is because the research was done differently in the three strategies. That represents a human decision process – critical to the state specific strategy effort.”
Although the comparison between state strategies was itself novel, the researchers believe their assessment of “trackability” and “stackability” of conservation practices will be even more useful to decision makers. They drew on expert opinions to assign a trackability score to each practice. For example, conversion of land from an annual row cropping system to a woody buffer strip is highly trackable using satellite imagery. But others? Not so much.
“Thinking of an in-field practice like how much nitrogen a farmer applies; there’s no reliable way to track that,” Reid notes. There are ways to estimate it, but not directly track,” Reid says.
“Because a farmer just decides it and does it,” Laura adds. “And we have x number of farmers across Illinois and the whole Mississippi watershed. How can we track that?”
The researchers say it’s important to know how trackable these practices are, because stakeholders investing in nutrient loss reduction need to be able to pinpoint what’s working and what’s not and be able to tell a story of improvement with the resources invested.
“We’re working towards developing a framework to keep track of what all 12 states are doing, and how many practices they’re adopting. It’s a big undertaking,” Laura says. “It’s not just research for us. We’re working towards coming up with something states could use for the next 20 years.”
The researchers also considered how easily the practices could be paired up, or stacked.
“For example, land use change doesn’t really pair with anything because you’re completely changing the way business is being done. For example, if you’re growing switchgrass, you don’t need a cover crop or conservation tillage. It just doesn’t stack well with anything. But cover crops, bioreactors, and others pair with many practices well,” Laura says.
Although the researchers assessed the feasibility of stacking, they still don’t know the potential effects of pairing the conservation practices. “You may have multiple practices on the same acre, but what is the resulting impact on water quality? We don’t know yet - that’s where we need more field research,” Reid says.
The study also touched on cost effectiveness of the various practices. For example, nitrogen management – changing the amount of fertilizer applied – is one of the least expensive practices. It is also relatively easy for farmers, and is highly stackable with other practices. But Laura says it’s important to consider its effectiveness and trackability, too.
“So even though it’s relatively cheap, is this something we should be telling states to invest a lot of money in? It’s not as effective as other practices and harder to track. With this study, we wanted to get a handle on how well the practices work, then take it a step further and ask whether the best practices are easiest or hardest to track. And, ultimately, what are farmers going to be interested in?”
The article, “Beyond the nutrient strategies: Common ground to accelerate agricultural water quality improvement in the upper Midwest,” is published in the Journal of Environmental Management. Reid and Laura’s co-authors include Gregory McIsaac, from U of I’s Department of Natural Resources and Environmental Sciences, and Carol Wong, Matthew Helmers, David Mulla, and Moira McDonald. The work was supported by the Walton Family Foundation.
In sweet corn, workhorses win
URBANA, Ill. – When deciding which sweet corn hybrids to plant, vegetable processors need to consider whether they want their contract growers using a workhorse or a racehorse. Is it better to choose a hybrid with exceptional yields under ideal growing conditions (i.e., the racehorse) or one that performs consistently well across ideal and less-than-ideal conditions (i.e., the workhorse)? New research from the University of Illinois suggests the workhorse is the winner in processing sweet corn.
“Experts say the ideal cultivar would have exceptional yield regardless of the weather, and across a large area, but it’s unknown if such cultivars are commercially available,” says Marty Williams, an ecologist with the Department of Crop Sciences at U of I and USDA-ARS.
Williams says a number of crops have been studied for yield stability, a cultivar’s ability to produce consistent yields across inconsistent environments. The work has resulted in several recommendations about where to grow specific cultivars for the best results.
“Stability analysis is valuable, particularly given the increased weather variability we’re facing. However, previous studies always stopped with recommendations. No one appears to have quantified if such recommendations are followed. Our work is about how yield stability of individual hybrids actually relates to hybrid adoption in sweet corn,” he says. Although the focus is on sweet corn, the study is the first to link a cultivar’s yield stability with adoption in any crop.
Williams obtained data from an anonymous vegetable processing company, representing more than a decade of sweet corn hybrid assessment trials across the upper Midwest and the Pacific Northwest. He pulled the number of cases produced per acre – a yield metric important to processors that he calls ”case production” – from each trial, and then incorporated environmental data to calculate yield stability for 12 of the most commonly planted hybrids grown for processing.
Performance of each hybrid was related to all other hybrids across a wide range of growing conditions. This enabled Williams to assign each hybrid to categories of high, average, and low stability and high, average, and low yield. He found 10 hybrids were average for both stability and yield. A few hybrids had above-average yield or above-average stability, but none had both, suggesting the ”ideal” sweet corn hybrid does not yet exist.
Williams then analyzed another dataset representing nearly 15,000 processing sweet corn fields over a period of 20 years. He was able to calculate the acreage planted in each of the 12 hybrids from the hybrid assessment trial. Those 12 hybrids accounted for most of the acreage planted to sweet corn over the 20-year period for the processor.
Most hybrids accounted for 1 to 4 percent of the planted acreage. However, he found a single hybrid was planted on disproportionately more acres: 31.2 percent, to be exact. That hybrid was the only one exhibiting above-average stability across variable growing conditions.
In processing sweet corn, vegetable processors – not growers – choose the hybrid for each field. Processors need hybrids that lend themselves to machine harvest, ears that hold up to processing, and kernels that maintain quality as a finished product. Williams says vegetable processors also consider the capacity of their processing facilities.
“When sweet corn is ripe, it must be harvested. Moreover, unlike grain corn which can be stored prior to use, sweet corn must be processed and preserved immediately after harvest,” Williams explains. “Midwest processors want to have their plants running at capacity throughout the approximately three-month harvest window. A plant running significantly above or below that capacity is costly. I suspect a racehorse hybrid is problematic because it’s difficult to predict its performance when the weather deviates from ideal growing conditions, which is common in the Midwest.”
Evidence that vegetable processors prioritize stability could inform future sweet corn breeding programs, and, according to Williams, it could provide a sense of security for growers. “Growers are more likely tasked with growing a workhorse over a racehorse. That decision buffers them, as well as the processor, from less-than-ideal growing conditions,” he says.
The article, “Genotype adoption in processing sweet corn relates to stability in case production,” is published in HortScience.
New study shows producers where and how to grow cellulosic biofuel crops
URBANA, Ill. – According to a recent ruling by the United States Environmental Protection Agency, 288 million gallons of cellulosic biofuel must be blended into the U.S. gasoline supply in 2018. Although this figure is down slightly from last year, the industry is still growing at a modest pace. However, until now, producers have had to rely on incomplete information and unrealistic, small-scale studies in guiding their decisions about which feedstocks to grow, and where. A new multi-institution report provides practical agronomic data for five cellulosic feedstocks, which could improve adoption and increase production across the country.
“Early yield estimates were based on data from small research plots, but they weren’t realistic. Our main goal with this project was to determine whether these species could be viable crops when grown on the farm scale,” says D.K. Lee, associate professor in the Department of Crop Sciences at the University of Illinois and leader of the prairie mixture portion of the study.
The project, backed by the U.S. Department of Energy and the Sun Grant Initiative, began in 2008 and includes researchers from 26 institutions. Together, they evaluated the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures in long-term trials spanning a wide geographical area. Due to shortages in plant materials, Miscanthus and energycane were grown on smaller plots than the other crops, but researchers say the new results are still valuable for producers.
“Although making real-world decisions and recommendations based on performance data from small plots is less desirable than from field-scale plots, we feel comfortable with the Miscanthus results since they were based on 33 data sets collected from five sites over seven years,” says Tom Voigt, professor in the crop sciences department at U of I and leader of the Miscanthus portion of the study.
Crops were grown for five to seven years in multiple locations and with varying levels of nitrogen fertilizer. Although most of the crops are known to tolerate poor soil quality, the researchers found that they all benefitted from at least some nitrogen. For example, Miscanthus did best with an application of 53.5 pounds per acre.
“When we didn’t fertilize with any nitrogen, yields dropped over time. But if we used too much, 107 pounds per acre, we were increasing nitrous oxide emissions and nitrate leaching,” says Voigt. “There is some need for fertilization, but it should be tailored to specific locations.”
Prairie mixtures, which were grown on land enrolled in the Conservation Reserve Program (CRP), also benefitted from added nitrogen. Yield kept increasing with the addition of up to 100 pounds per acre, but Lee says producers would have to weigh the yield benefit against the cost of the fertilizer.
“Even though it increased yield, it is economically not profitable to use more than 50 pounds of nitrogen per acre.”
And although most of the crops are somewhat drought-tolerant, precipitation made a difference.
“Miscanthus production was directly related to precipitation,” Voigt says. “In areas where precipitation was down, yields generally dropped. However, it did depend on timing. If there was a good amount of water in the winter, plants could get going pretty well in the spring. But if we had little rainfall after that, that hurt yields.”
Lee says prairie mixtures, which are normally made up of hardy grasses, suffered from the severe droughts in 2012 and 2013 in some locations. “In one year in our Oklahoma location, they didn’t even try to harvest. Yield was too low.”
No one feedstock “won” across the board. “It depends so much on location, nitrogen application rate, and year variability,” Voigt says. Instead of highlighting specific yields obtained in good years or locations, a group of statisticians within the research team used field-based yield and environmental data to create maps of yield potential for the five crops across the U.S. Dark green swaths on the maps represent areas of highest yield potential, between 8 and 10 tons per acre per year.
According to the new results, the greatest yield potentials for lowland switchgrass varieties are in the lower Mississippi valley and the Gulf coast states, whereas Miscanthus and prairie mixture yields are likely to be greatest in the upper Midwest.
Lee says the prairie mixtures, which are typically grown on CRP land to conserve soil, didn’t live up to their potential in the study. “We know that there are higher-yielding switchgrass varieties today than were included in the CRP mixtures in the study. If we really want to use CRP for biomass production, we need to plant highly productive species. That will bump yield up a lot higher.
“One of the biggest concerns now is that CRP enrollment is shrinking. When we started, we had 36 million acres nationwide. Now we’re down to 26 million. Farmers feel they could make more money by using that land for row crops. We need to find some solution if we want to save the soil. Biomass could provide revenue for farmers, if they were allowed to harvest it,” Lee says.
Energycane could reach very high yields, but in a relatively limited portion of the country. However, the crop that shows the highest potential yields in the greatest number of locations is sorghum. The annual crop is highly adaptable to various conditions and might be easier for farmers to work with.
“It fits well in the traditional annual row-crop system; better than perennial crops. It may not be environmentally as desirable as perennial crops, but people could borrow money in winter to buy seed and supplies, then plant, and sell in the fall to pay back their loans. It’s the annual cycle that corn and beans are in,” Voigt says.
Lee adds, “In terms of management, sorghum is almost the same as corn. It germinates and grows so quickly, weed control is not a big issue. If you plant by early June, it will be 15-20 feet tall by September. It also has good drought tolerance.”
Downsides to the biomass champ? It’s wet at harvest and can’t be stored. It also requires nitrogen and can lodge, or collapse, prior to harvest in wet or windy conditions. “Still, it’s a really spectacular plant,” Voigt says.
The researchers made all the raw data from the study available online for anyone to access. Lee says it can be useful for everyone: scientists, policymakers, and producers. “It should be helpful for number of different stakeholders,” he says.
The article, “Biomass production of herbaceous energy crops in the United States: Field trial results and yield potential maps from the multiyear regional feedstock partnership,” is published in a special issue of GCB Bioenergy. The project was funded through the U.S. Department of Energy [award number DE-FC36-05GO85041] and the North Central Regional Sun Grant Center at South Dakota State University.