- Although soybeans are one of the most widely grown crops in the U.S., few soybean farmers are using organic practices.
- A new University of Illinois report details organic products and practices to combat pathogens and insect pests.
- New growers may be motivated by a strong profit margin for organically produced soybeans.
URBANA, Ill. – Soybeans were planted on nearly 84 million acres in the U.S. in 2016, but only a tiny fraction—less than 1 percent—were grown organically. This number has been increasing in recent years, and a group of University of Illinois researchers wants to give organic growers the tools they need to combat pathogens and insect pests.
“We wanted to give organic growers some opportunities. We summarized some practices to fight diseases and pests organically. It’s not an easy task, but it can be done,” says U of I and USDA ARS crop pathologist Glen Hartman.
Hartman, along with colleagues in the Department of Crop Sciences, produced a comprehensive report summarizing the disease and pest problems faced by soybean growers in the United States. For the first time, the report compiles specific organic management practices and products tailored for each scenario. By detailing the tools needed to successfully grow organic soybeans, the researchers hope more growers will give it a try.
“There is a movement for organic agriculture, but so far, soybeans haven’t been a major player,” Hartman notes.
The researchers want to encourage small-scale vegetable farmers that are already using organic practices to add soybeans to the mix. The expansion of the organic meat and dairy markets, combined with strong consumer interest in organic soy-based foods like tofu and edamame, are increasing the demand for organically grown soybeans. Over half of organic soybeans are imported, but several companies and entrepreneurs are working to increase the domestic supply.
Those who are selling organic soybeans today are getting almost twice as much per bushel compared to conventional soybeans. “Organic meat is probably double or triple the price compared with conventionally raised meat. And that’s partly from the cost of organic feed. Whoever’s producing this is going to make some money,” Hartman says. “Bags of frozen edamame sell for about $3 at the grocery store, and there might be 40-50 pods per bag. That’s equivalent to one or two plants. You can grow maybe 100,000 plants in an acre. You can do the math, and that’s a rough calculation, but there could be a lot of profit involved.”
Graduate student Theresa Herman also sees the potential for increased edamame production in the United States. “I have talked to school food service companies about incorporating edamame in school lunch programs. It’s a good source of protein, and kids eat the beans voraciously. They’re crazy about edamame,” she notes.
Soybeans grown for edamame appear to be more prone to insect and disease problems than grain soybean, and non-GMO grain varieties available to organic growers may not have the disease and pest resistance that is present in many elite conventional cultivars. However, there are organic solutions for both. In the report, the researchers lay out strategies in a number of categories, including biological control, cultural practices, breeding priorities, and organic pesticide products.
“Rotations to different crops are commonly used by organic growers,” Hartman says. “Organic producers have cover crops and alternative crops that are not used in most corn and soybean systems. They might have a four- to six- to eight-year rotation, which is one of the best ways to reduce diseases.”
Although the researchers point to the promise of longer rotations and cover crops, they would like to know more about the effectiveness of organic products and practices in real-world settings.
“We want to be able to experimentally test some of the products growers are using in organic soybean systems. We want to learn what their constraints are, and how we can help them,” Hartman says.
Herman adds, “A lot of people are happy with the way they do things, but they want to know more about why and how their system is working.”
Current and potential organic soybean growers can contact Hartman directly, and can read the new report, “Organically grown soybean production in the USA: Constraints and management of pathogens and insect pests,” published in Agronomy.
Pumpkin crop looking good in time for Halloween and Thanksgiving
URBANA, Ill. – This time last year, the threat of a major pumpkin shortfall was in the news. Sources were predicting that the 50 percent yield losses—due to early rains, cooler-than-normal weather, and fast-spreading disease—would mean fewer pumpkin pies at Thanksgiving. But thanks to manufacturer decisions not to reserve stock for after the holiday, the doom and gloom scenario was largely not borne out. Still, the lead-up to Thanksgiving was a tense time for the pumpkin industry.
This year, according to University of Illinois plant pathologist Mohammad Babadoost, the pumpkin outlook is much improved.
“The season started out very well,” Babadoost says. “There was enough rain to germinate seeds, but not too much. Then there was a period of relatively warm and dry conditions, which pumpkins love. Germination and plant establishment were good and fruit set was very good. Harvesting was timely. The product, I’ve been told, is very good.”
A scare came in mid-August, when downy mildew reared its head in some fields. This fast-spreading fungus was one of the pathogens that wreaked havoc on the pumpkin crop in 2015. Fortunately, its occurrence has been confined to a small area in Tazewell County, Illinois, and it has not been a significant problem elsewhere.
Other isolated diseases have been detected. For example, a bacterial disease has been on the rise in jack-o’-lantern pumpkins across the Midwest and worldwide for the past seven to eight years.
“This bacterial disease affects leaves and fruit. When the disease gets onto pumpkins, it produces tiny spots, or lesions. Growers can’t see them unless they are very carefully examining the fruit. Those tiny lesions are then colonized by opportunistic bacteria and fungi, and then the fruit just collapses. We are working very hard to find good management, but it takes time,” Babadoost explains.
A few farms in Illinois and Indiana have observed fruit rot after seemingly healthy pumpkins were placed into bins for sale. Babadoost investigated and discovered that the problem was worker sanitation.
“The workers cut and collect the fruit and put it in the bin, which goes to the warehouse and finally to the stores,” Babadoost says. “A few pumpkins in the field are affected by phytophthora—a fungal pathogen—and are rotting on the soil side. Workers pick them up and realize the pumpkins are decaying. They put the infected pumpkins down, but their hands are now contaminated. When they pick up healthy pumpkins and put them in the bin, their contaminated hands transfer the pathogens to the uninfected pumpkins. After a few days, the pumpkins start rotting from the top or sides, wherever the worker touched them.
“Growers should be very careful. If workers touch infected pumpkins, they have to decontaminate their hands. Use alcohol or wash before touching uninfected pumpkins. That was a new observation this year. I saw spectacular rotting in the bin,” Babadoost notes.
Some farmers have complained of rodent damage in the field this year. Jack-o’-lantern carvers can relate, recognizing those unwelcome chew marks on Halloween pumpkins. Babadoost says the squirrels and mice are after the seeds inside, even though most are scooped out before carving. If pumpkins are displayed on porches, it is not uncommon for them to rot after only a few weeks. But if they are kept dry, Babadoost says, most pumpkins can last a very long time. A large uncarved white pumpkin has decorated his lab space for over 14 months, with no sign of fruit rot.
Babadoost is an enthusiastic champion for the pumpkin industry, and hopes the public will take advantage of everything the season offers. “Pumpkins bring people together, through baking, family visits to pumpkin patches, and other autumn traditions. And this year, there will be no shortage of pumpkin pie at the Thanksgiving table.”
New booklet gives farmers strategies to reduce nitrogen runoff
- Water draining from farm fields in the Midwest is typically loaded with excess nitrogen, polluting local and distant waterways.
- A new booklet published by University of Illinois Extension describes ten nitrogen loss-reduction strategies for farmers.
- Using the information in the booklet, farmers can choose the most appropriate and cost-effective solution for their specific circumstances.
URBANA, Ill. – The Midwest, blessed with rich soils and abundant precipitation, leads the country and the world in corn and soybean production. It also contributes the majority of the nitrate load in the Gulf of Mexico, leading to its large low-oxygen “dead zone.” Nitrate applied to farm fields also winds up in local drinking water supplies, which must be removed at a major cost to municipalities. Fortunately, there are ways for farmers to reduce nitrogen loss, and a new University of Illinois Extension booklet provides details on 10 suggested practices.
“In this booklet, we present a consistent source of information about a variety of practices that can reduce nitrate in drainage water,” says University of Illinois assistant professor of water quality Laura Christianson.
The 10 practices described in the booklet are broken down into three categories: reducing nitrate in the plant root zone, reducing delivery of nitrate to the field’s edge, and removing nitrate at the edge of the field or downstream.
“We wanted to present a variety of options that are practical for farmers, and provide some comparison between the practices. Where does each practice work? How much will it cost? How well does the practice work? People can get a good idea of what’s going to work for them,” Christianson says.
To reduce nitrate in the plant root zone, farmers can improve nitrogen management, plant winter cover crops, or increase their use of perennials. These practices minimize the amount of nitrogen that enters drainage tile pipes in the first place.
Christianson explains that many farmers in Illinois are already applying nitrogen fertilizers at the university recommended rate. “For them to reduce their rate wouldn’t make any sense and wouldn’t provide water quality benefits. The timing of nitrogen application and use of nitrification inhibitors are probably the management changes I’d focus on more rather than rate, as long as you’re following university guidelines,” she says.
Farmers might instead choose to change the physical drainage system in their fields. The practices recommended in the booklet include adding controlled drainage structures to keep drainage water in the soil; recycling drainage water; and reducing drainage intensity by increasing spacing between drains and decreasing drain depth.
“The new practice of drainage water recycling is especially exciting because there is a significant potential to increase crop yields by storing drainage water and reapplying it when it’s needed by the crop. This practice doesn’t come cheaply, but could be good for yields and downstream waters,” Christianson notes.
The final category consists of edge-of-field practices including adding bioreactors or constructed wetlands, converting drainage ditches to two-stage ditches, or using saturated buffers. Christianson is a vocal advocate of bioreactors, and admits that this practice is her personal favorite. But she knows other practices might hold more appeal.
“The important thing is just trying something new—getting a new practice on the landscape to improve water quality. A bioreactor might not work for someone, but they might want to do a cover crop and that’s great,” Christianson says. “In fact, cover crops might have the biggest chance of adoption. And if everyone started planting cover crops, especially grass-based cover crops that overwinter like cereal rye, that would be our best chance of having a positive water quality impact.
“Really, the best practice is the one that works for each individual farmer. That’s why providing a list of options and being able to compare them is important,” Christianson says.
Each practice comes with a detailed description explaining what it is, how it improves water quality, how effective it is, where it will work, whether it has any additional benefits, and its level of acceptance. The booklet also contains a chapter on economic considerations of each strategy. An online course for certified crop advisors is being developed to accompany the booklet, with a likely launch near the end of spring 2017.
The booklet, “Ten ways to reduce nitrogen loads from drained cropland in the Midwest,” is co-authored by Extension faculty from Purdue University, South Dakota State University, Iowa State University, and the University of Minnesota, and collaborators at the Iowa Soybean Association. It is currently available as a free download at Christianson’s website, or printed copies can be purchased for a nominal fee at PubsPlus.
New method provides a tool to develop nematode-resistant soybean varieties
- Many soybean varieties have a naturally occurring genetic resistance to the soybean cyst nematode, a major pest affecting the crop.
- The number of copies of the resistance gene varies among cultivars; a new method, developed by University of Illinois researchers, is able to efficiently quantify this variation for the first time.
- The new method has been tested in greenhouse trials to show that the more copies of the gene, the greater the resistance to soybean cyst nematode.
- Breeders can use this method to develop new soybean varieties with greater and more reliable resistance.
URBANA, Ill. – Soybean cyst nematode is the number one soybean pest worldwide, accounting for estimated annual losses of nearly $1.3 billion in the United States. Some soybean varieties have resistance to the tiny parasitic worms through conventional breeding of naturally occurring resistance genes, but the current level of resistance is becoming less reliable.
“Our interest is in finding new sources of resistance, because the sources that people have been using are breaking down. Nematodes are becoming better at overcoming the resistance we have in current cultivars. We are also, interested in improving our understanding of how this resistance works so we can do a better job of selecting for it,” says University of Illinois plant breeder, Brian Diers.
In 2012, U of I geneticist Matthew Hudson, Diers, and Andrew Bent, a collaborator at the University of Wisconsin, discovered the naturally occurring genetic locus (region on a chromosome) that is critical in controlling resistance to soybean cyst nematode, but that was only the beginning.
“It turns out that at this locus, there’s a repeat of four genes,” Diers explains. “Different diverse soybean types that are resistant have different numbers of repeats. For example, in PI 88788, which is the original source of SCN resistance for most soybean varieties in the Midwest, there are nine repeats of those four genes. In the susceptible varieties, there’s only one copy of those four genes. Another source of resistance, Peking, has three copies of those repeats.”
This difference in repeat number is known as copy number variation, and is more common than previously thought. But before now, there was no easy or cost-effective way to quantify the number of gene repeats. Using a method recently developed in Hudson’s laboratory, the number of gene repeats can be accurately monitored by measuring the ratio between two genes.
Although the researchers suspected that having more copies of the gene sequence might confer a greater degree of resistance, they had no way of testing their suspicions before the new assay was developed. After getting the new assay, the team set to work again.
“We grew soybean plants in a greenhouse, inoculated them with nematodes, and then used the assay to determine how many repeats each plant had. As predicted, we found that the more repeats a plant had, the more resistant it was,” Diers explained. “This proved that the number of repeats is important.”
Armed with this information, the researchers plan to look at the number of repeats present in existing nematode-resistant soybean varieties in an attempt to explain why some display better resistance than others in field settings. They also plan to improve breeding programs by ensuring parental lines have the maximum number of repeats available in a given genotype, and to select for new variants with additional copies that may show superior resistance.
“Ultimately,” Diers adds, “if we can select for more copies, that could benefit farmers because we could get stronger resistance. Breeders will now have better tools to select for and verify resistance.”
The research described here is published in two articles. “An efficient method for measuring copy number variation applied to improvement of nematode resistance” is published in The Plant Journal. Lead author Tong Geon Lee is now at the University of Florida. Diers and Hudson, from U of I, are co-authors. “Impact of Rhg1 copy number, type, and interaction with Rhg4 on resistance to Heterodera glycines in soybean” is published in Theoretical and Applied Genetics. Lead author Neil Yu is now at Monsanto, and co-author Daniele Rosa is at the Federal University of Vicosa, Brazil. Lee, Hudson, and Diers are additional co-authors. Both studies were supported by the United Soybean Board.
Soil microbes flourish with reduced tillage
- Microbes improve soil quality by cycling nutrients and breaking plant residues down into soil organic matter.
- In an effort to detect consistent patterns across a large geographical area, University of Illinois researchers conducted a meta-analysis of 62 studies examining the effect of tillage on soil microbes.
- No-till systems had greater soil microbial biomass and enzymatic activity. Tilled systems that used a chisel plow were equivalent to no-till systems, in terms of microbial biomass.
URBANA, Ill. – For the past several decades, farmers have been abandoning their plows in favor of a practice known as no-till agriculture. Today, about one-third of U.S. farmers are no longer tilling their fields, and still more are practicing conservation tillage—using equipment that only disturbs the soil to a minimal degree. No-till and, to a lesser degree, conservation tillage maintains or improves soil quality by preserving soil structure and moisture, increasing soil organic matter, and providing habitat for soil microbes.
It’s the microbes that matter most.
“Soil microbes are the workhorses of the soil. They break down crop residues and release nitrogen, phosphorus, potassium, and other nutrients back to the soil so they’re plant-available. We want a healthy, diverse microbial community so that those processes can happen and improve our soils,” says University of Illinois doctoral student Stacy Zuber.
Until now, most studies linking tillage intensity and microbial activity have been done at the scale of individual farms. Most of these studies do find more soil microbes with no-till management, but the magnitude of that result varies a lot from farm to farm. That’s because each farm is influenced by different environmental factors, agronomic practices, and soil type. Where no-till is compared with tillage, the type of equipment and tillage depth also differs.
Zuber wanted to cut through the confusion to detect a true “signal” of the effect of tillage on soil microbes. To do that, she compiled and analyzed data from 62 studies from all across the globe.
“When you’re doing individual field experiments—even if you have several in one area—you’re still focused on the one region,” Zuber notes. “Sometimes it’s hard to see the big picture because there’s so much variability. The meta-analysis allowed us to look at different field studies from around the globe to determine the overall effect. This process lets us see that big picture.”
Zuber compared measures of microbial biomass and metabolic activity in no-till and tilled systems. For tilled systems, she included categories that accounted for the type of tillage equipment and tillage depth. She also accounted for the nitrogen fertilization rate, mean temperature and precipitation, the presence or absence of cover crops, and other variables.
When the data from all 62 studies were analyzed together, it turned out that microbial biomass and enzymatic activity were greater in no-till than in tilled systems. In tilled systems, the type of tillage equipment mattered. In contrast to other tillage equipment, such as moldboard plows or disc plows, the use of chisel plows was associated with greater microbial biomass. Chisel plows, which theoretically result in minimal soil disturbance, are commonly used as part of a conservation tillage system.
But experimental use of a chisel plow, as represented in the studies Zuber analyzed, may be different from how they are used in the real world.
“Tillage seems simple: you break up the soil or you don’t. Things get complicated when you start looking at tillage implements, because there is no clear definition and common use for them. You can have two implements called chisel plows, but they can work the soil completely differently. For example, if they go across the field in one pass, that’s not much disturbance. But if they make two or three passes, it’s a lot more disruptive,” Zuber explains.
The study suggests that since soil microbial biomass and enzymatic activity can stand in as proxies for soil quality, farmers should consider moving toward no-till or conservation tillage systems.
Zuber says, “Helping the soil function better helps your crops grow better, and can also maintain high quality soil for sustainability purposes. In Illinois, we have such great soil; it’s our biggest resource. Farmers can help protect it by making sure the microbial community is healthy.”
The article, “Meta-analysis approach to assess effect of tillage on microbial biomass and enzyme activities,” is published in Soil Biology & Biochemistry. Zuber and co-author Maria Villamil are in the Department of Crop Sciences at U of I. The work was part of a regional collaborative project entitled “Cropping Systems Coordinated Agricultural Project (CSCAP)” and was supported by USDA-NIFA.
Diplodia ear mold at harvest: What can be done now?
URBANA, Ill. – Corn producers in western and west-southwestern Illinois should be on the lookout for symptoms of Diplodia ear mold during harvest. An informal survey of several grain elevators and farmers in Western Illinois reported up to fifty percent kernel damage in some locations. Factors such as planting date, the timing of rain events after fertilization, and hybrid susceptibility can result in a range of damage within the larger region and even within a farming operation, according to University of Illinois Extension educator Angie Peltier.
“Diplodia ear mold can cause lightweight kernels with a dull grey to brownish color and sometimes small black fruiting structures call pycnidia,” Peltier says. Infected kernels are prone to breakage and can result in poor test weights, poor grain quality, and fine materials in the hopper or grain bin. Peltier recommends adjusting combine settings to maximize grain cleaning and minimize breakage.
Elevator and ethanol facility personnel suggest that the threshold for accepting damaged grain can vary depending upon the local market and end-use. The price at which a farmer can market grain begins to decrease for every percentage point of damaged kernels above five percent.
“Some grain elevators will set a damage threshold above which they will not accept the grain. I have heard anywhere from above 15 to 50 percent damage, depending upon the end use and how quickly the grain will leave the elevator,” Peltier says.
Stenocarpella maydis, the fungus that causes Diplodia ear mold, metabolizes the starches in corn kernels leaving them lighter weight than non-infected kernels. The ethanol manufacturing process uses bacteria to turn corn starch into simple sugars, eventually fermenting them to yield ethanol. Diplodia-damaged kernels can yield less ethanol and may explain why elevators that supply ethanol plants may have a lower threshold for damaged kernels than others.
One positive is that unlike Aspergillus, Fusarium, or Gibberella ear molds, Diplodia ear mold is not associated with a mycotoxin. Regardless of whether infected kernels are in the field, in the combine hopper, semi-trailer, or grain bin, the fungus will continue to grow and metabolize starches unless the grain is cooled and dried to below 15 percent moisture. Unless properly dried, the fungus can colonize uninfected kernels that are damaged during harvest or storage operations.
With on-farm storage, many crop producers have the option to hold onto their grain to market it at a later time.
“I recommend storing diseased grain separately and for only short periods of time to reduce the chance of additional losses,” Peltier says.
It is important for producers that encounter Diplodia ear mold to be in communication with their crop insurance agent. While the high yields expected this year may offset lower grain prices overall, those farmers with low sale prices due to a lot of dockage may be able to recoup some of their losses.
For additional resources on drying and storing grain, and for more general information on Diplodia, visit the Bulletin.
Farming with forests
- In the race to feed a growing population, it is important to consider sustainability.
- University of Illinois researchers are promoting the practice of agroforestry—the intentional planting of trees and shrubs with crops or livestock—to achieve sustainability goals.
- A number of practical and policy challenges have prevented adoption of agroforestry practices on a large scale in the U.S.
- If adopted more widely, agroforestry could benefit wildlife, soil and water quality, and the global climate.
URBANA, Ill. – Feeding the world’s burgeoning population is a major challenge for agricultural scientists and agribusinesses, who are busy developing higher-yielding crop varieties. Yet University of Illinois researchers stress that we should not overlook sustainability in the frenzy to achieve production goals.
More than a third of the global land area is currently in food production. This figure is likely to expand, leading to deforestation, habitat loss, and weakening of essential ecosystem services, according to U of I agroecologist Sarah Taylor Lovell and graduate student Matt Wilson. To address these and other problems, they are promoting an unconventional solution: agroforestry.
Agroforestry is the intentional combination of trees and shrubs with crops or livestock. Or, as Wilson simply puts it, “You stick trees or shrubs in other stuff.”
The researchers describe five agroforestry practices:
- Alley cropping: field crops planted between rows of trees.
- Silvopasture: trees added to pasture systems.
- Riparian buffers: trees planted between field edges and river edges.
- Windbreaks: trees planted adjacent to planted fields and perpendicular to the prevailing wind pattern.
- Forest farming: harvest or cultivation of products—such as mushrooms, ginseng, or ornamental wood—in established forests.
Each of the five practices can benefit conventional and organic agroecosystems in similar ways. Woody plants can provide habitat for beneficial wildlife, prevent soil erosion, sequester atmospheric carbon, and absorb nutrient runoff while providing farmers with additional streams of income in the form of lumber or specialty products like nuts or berries. Each specific practice also provides unique benefits. For example, trees added to pasture landscapes provide shade to grazing livestock.
Farmers might be concerned about the trees casting too much shade on crops, but it is simply a matter of choosing the right complement of species. For example, the combination of winter wheat and walnut trees in an alley cropping system works well.
“Winter wheat grows in the late winter or early spring, but the walnut doesn’t leaf out until late spring,” Wilson explains. “So, when you mix the two together, you’ve got the benefit of having two crops growing in different parts of the year.”
Lovell adds, “The grain crop growing near the trees can actually force the trees to grow deeper roots. This can benefit individual trees because the root zone they’re forced to occupy gives them greater access to water.”
European farmers are ahead of their U.S. counterparts in terms of their adoption of agroforestry practices. “It’s very common in Europe. A lot of farmers are already doing hedgerows, which are similar to windbreaks, as part of their agroforestry systems, and even more integrated systems are fairly common,” Lovell says.
Wilson suggests that there are cultural barriers to adopting agroforestry practices in the U.S. “We’ve had some farmers share sentiments like, ‘why should I plant trees? My grandpa spent his whole life tearing trees out so he could put crops in.’ There’s definitely some perception that trees are not good in a farm landscape. Trying to overcome that has been a challenge,” he says.
Another obstacle in the U.S. is a policy mindset that treats production and conservation as completely separate functions of the land. For example, farmers are prohibited from harvesting or selling products from land designated for conservation, as in the USDA’s Conservation Reserve Program. There are USDA programs that support certain agroforestry practices such as wind breaks, but government support for more integrated practices is generally lacking. That’s why Lovell’s team is advocating for farmers to utilize marginal land.
“We are working with farmers to identify lands that are less productive, sensitive, or marginal, and suggesting those as the places to start transitioning,” Lovell explains. Or, she suggests, farmers could plant young “edibles” (trees and shrubs bearing fruit or nuts) in a CRP easement. By the time the CRP lease expires in 10 to 15 years, the trees would be mature, bearing edible—and potentially profitable—products.
The long timeframe needed for trees to establish and mature may discourage some farmers, but the researchers offer a strategy for the transition period. In an alley cropping system with hazelnut and chestnut trees, for example, they suggest growing edible shrubs and pasture between rows. Farmers can expect to start harvesting and selling hay almost immediately, and will start seeing fruit production from the shrubs within a couple of years. Eight to ten years after establishment, trees will begin producing nuts.
“We’re looking at economic strategies to maximize profit from the very beginning,” Lovell says.
Despite the challenges, the researchers insist the environmental benefits are worth the trouble. “If you have trees in a system, you’re holding soil, preventing runoff, and ameliorating greenhouse gas emissions. At the same time, you are getting a harvestable product. This combination of environmental services and agricultural production makes agroforestry an exciting opportunity to both feed the world and save the planet,” Wilson says.
The article, “Agroforestry—The next step in sustainable and resilient agriculture,” is published in Sustainability. The research was supported by the Jonathan Baldwin Turner Fellowship though the Department of Crop Sciences at the University of Illinois. The full text of the article is freely available at the journal’s website.
Soil management may help stabilize maize yield in the face of climate change
- Given that predicted climate changes are expected to affect maize yields, many researchers and companies are focusing on improving maize varieties to withstand more stressful environments.
- A new study shows that climate effects on maize yield can be mitigated by soil water holding capacity and soil organic matter.
- Cover cropping and other methods of improving soil organic matter may result in a more stable maize crop in future climates.
URBANA, Ill. – How will we feed our growing population in the face of an increasingly extreme climate? Many experts suggest the answer lies in breeding novel crop varieties that can withstand the increases in drought, heat, and extreme rainfall events predicted in the not-too-distant future. But breeding is only part of the equation, according to new research from the University of Illinois and several collaborating institutions across the Midwest.
“It might not be necessary to put all the stress of climate adaptation and mitigation on new varieties. Instead, if we can manage agroecosystems more appropriately, we can buffer some of the effects of climate instability,” says U of I and USDA Agricultural Research Service ecologist Adam Davis.
To find the management tool that could ameliorate the effects of climate instability, Davis and his collaborators had to go beyond the traditional field-scale experiment. “We had to think at a much broader spatial scale,” he notes.
The team obtained weather, soil, and yield data from every county in four states—Illinois, Michigan, Minnesota, and Pennsylvania—across a span of 15 years. They then used a new analytical approach, which borrowed from economic concepts, to determine the effects of weather and soil properties on maize yield.
“The things that were most effective at buffering against the different forms of yield instability were soil organic matter and water holding capacity,” Davis says. This pattern was true across all years and all study locations.
Greater water holding capacity, which increases with more soil organic matter, gives crops an advantage in hot, dry climates. They can continue to take up water from the soil, which means continued growth and strong yields even in adverse climates.
The good news for farmers is that they may be able to manage for improvements in water holding capacity, giving them a potential tool to support novel maize varieties. “In locations with coarse soils, you can see really quick and gratifying responses to soil organic matter amendments,” Davis says.
Davis suggests a number of practices to increase soil organic matter, including using cover crops, avoiding excessive soil disturbance, increasing crop rotation length, and adding composted manures. He points out that cover crops might be the best choice for some farmers.
“Cover crops are a great way for improving soil organic matter; even small amounts of cover crop biomass seem to have soil organic matter benefits,” Davis explains. “They also can have weed suppressive benefits, so cover crops may represent a win-win scenario.”
No matter which amendment practice farmers choose, he says, “soil organic matter amendments are an important place to start building a cropping system resilient to climate change.”
The study, “Soil water holding capacity mitigates downside risk and volatility in US rainfed maize: Time to invest in soil organic matter?” is published in the journal PLOS One. Funding was provided by the Agriculture and Food Research Initiative of the USDA’s National Institute for Food and Agriculture. The full article is accessible at the journal’s website.
Sustainable Student Farm open house and field tours
URBANA, Ill. – The University of Illinois Sustainable Student Farm (SSF) and Woody Perennial Polyculture (WPP) project will host an open house on Friday, Sept.16, from 3 to 6 p.m. at their site just south of the main Urbana campus.
The SSF serves as a production farm to provide U of I residence halls with locally grown, low-input sustainable food. In addition, the farm acts as a living laboratory to connect students, community members, and the state at large with regional, small-scale food systems.
The WPP project, located near the SSF, is the first large-scale, university-funded research site studying a savanna-based agroecosystem. Founded in 2012, the WPP site hopes to lay the foundation for a scientific understanding of the potential agricultural and ecological benefits of woody polyculture systems.
During the open house, U of I Dining Services will be serving delicious and free food and drink prepared from SSF produce. The SSF, the WPP, and the U of I Community Garden Plots will be giving tours throughout the afternoon.
Also included in the open house:
- The Fresh Press will be on hand for information about its new fiber garden and possible demonstrations.
- The U of I Architecture Department will be talking about farm stand display pieces and a washing/packing/shed complex members of the department built for the SSF.
- The Student Sustainability Committee, along with other affiliated groups will be on hand with information about projects happening on campus.
- College of ACES researchers will give presentations on current projects at the SSF and WPP.
Currently the SSF operates between 45 to 48 weeks per year, occupying 6 acres for outdoor field production and nearly 10,000 square feet of year-round high tunnel production. In addition to selling the majority of its produce to the residence halls, it also markets its produce directly to consumers on the U of I quad each Thursday from May to November.
The Sustainable Student Farm was created through a grant from the Student Sustainability Committee and is made possible by the continued support of the University of Illinois Dining Services, the Department of Crop Sciences, and the Student Sustainability Committee.
The farms are located at Lincoln Avenue and Windsor Road, just south of the main U of I campus in Urbana.
New corn disease identified in DeKalb County
URBANA, Ill. – A positive sample of bacterial leaf streak was found in a corn field in DeKalb County, Illinois, its identification verified yesterday by the USDA. With this presence in Illinois, bacterial leaf streak has been identified in 9 states: Colorado, Iowa, Illinois, Kansas, Minnesota, Nebraska, Oklahoma, South Dakota, and Texas. DeKalb is the only county in Illinois that has been verified to have the disease.
“Because this is a bacterial disease, fungicides cannot be expected to control or suppress it,” says Suzanne Bissonnette, University of Illinois plant clinic director and assistant dean for agriculture and natural resources with U of I Extension.
U of I Extension commercial agriculture educator Dennis Bowman adds, “Crop rotation and tillage are the best short-term management strategies if the disease is present in a field.”
Bissonnette says if growers suspect bacterial leaf streak in their field, they can submit a sample to the U of I Plant Clinic.
“We’d like to get a comprehensive idea of distribution in the state,” Bissonnette says. “Although there are currently no known methods to prevent it, differences in varietal susceptibility may point the way to sources of resistance.”
Bacterial leaf streak is caused by the pathogen Xanthomonas vasicola pv. vasculorum. The disease causes the formation of linear lesions between the veins on a corn leaf. The lesions look similar to gray leaf spot symptoms – although GLS lesions tend to be shorter, more rectangular, and to stay within their veinal borders.
“Bacterial leaf streak lesions are more irregular, often thinner and longer, will ‘bleed’ over the veinal border, and may have a halo when held up to the light,” Bowman explains.
In many Great Plains states where the disease has been found, symptoms first appear on the lower leaves and infection progresses up the plant. Typically these fields have been under pivot irrigation. Later infections may occur and show up primarily in the upper canopy. This was the case for the positive DeKalb County sample found in the survey of approximately 340 randomly selected fields in transects across 68 of Illinois’s 102 counties. The survey was conducted by APHIS-PPQ (Animal Plant Health Inspection Service), IDA (Illinois Department of Agriculture), CAPS (Illinois Natural History Survey’s Cooperative Agricultural Pest Survey) and U of I Extension.
Bissonnette says there is currently very little known about this disease. Further research is needed to develop a complete understanding of this disease, its impact, and strategies for long term management. However, APHIS notes it is not believed to present a health risk to people or animals.
For information about the biology, symptoms, or management of Xvv, visit http://cropwatch.unl.edu/bacterial-leaf-streak or http://broderslab.agsci.colostate.edu/corn-bacterial-leaf-streak/.