Algae: The Double-Edged Sword

Mark Rasmussen | Leopold Center for Sustainable Agriculture Director

We humans seem to have an affection and fascination with the color green—the green of money, the green grass of spring after a long winter, the green of a Christmas tree or the expanse of leaves in a deciduous forest.

Photo credit: Iowa Department of Natural Resources Beach Monitoring Program

But there are some forms of green that we look upon with suspicion or have grown to dislike—the green water of an algae bloom or the pond scum that covers the surface of our favorite beach.  We tend to lump different forms of life under the general term “algae” (including cyanobacteria, also referred to as blue-green algae, which are technically not algae at all!), so our relationship with algae can be confusing and somewhat complicated.

As photosynthetic organisms, algae use energy from sunlight to produce oxygen.  Over many eons of time, they are responsible for much of the oxygen in the atmosphere, and they are the original source of fossil carbon transformed deep in the earth into crude oil and natural gas. Algae are also the basis of many food chains in aquatic environments.

We look upon algae with favor when they are used to produce biofuels and nutrient rich dietary supplements. But then there are the “other” algae that are more suspect—blue-green algae.  (Remember, the blue-green algae are technically not algae at all, but early taxonomists used the term and it stuck.)  We especially need to be concerned with the blue-green algae that produce toxins as we enter another growing season here in Iowa.

Cyanobacteria, or blue-green algae, tend to do well in warm, slow-flowing, or stagnant water when both nitrogen and phosphorus are abundant and available. These nutrients, along with sunlight and temperature are the primary drivers of their growth. Some species can grow very rapidly in what is called a bloom.  In a pond they can be part of the natural process of turning a water body eutrophic when dense growth can cause a reduction in animal life due to the absence or limitation of oxygen.  In our agricultural world, blue-green algae growth can be the result of poor nutrient management when high levels of nutrients get into surface waters and stimulate growth.

Along with rapid growth, the production of harmful toxins from certain species of blue-green algae is of great concern. Children and small pets with less body mass are highly susceptible.  The toxins can also impact wildlife when they drink contaminated water.  Dried biomass on shore can also be toxic if inhaled as dust. Research has discovered that people who live or spend a lot of time near contaminated water have a greater risk of health effects just from being near this kind of water.

Toxin production in critical species is also stimulated by increased water temperature.  Therefore, we see more problems later in the summer as bodies of water warm.  Iowa began testing surface water in 2000, and every summer, beach closings and alerts are issued for water that has elevated levels of algae toxins. Climate change and hot summers which warm the water faster also stimulate toxin production and can be expected to increase the problem. 

It is difficult and expensive to purify water for drinking when water sources are contaminated, and most water treatment plants do not have that kind of purification capacity.  Last year the water in the Des Moines River in central Iowa was not useable for many weeks as a primary source due to the high level of toxins contained in the water.  Once contaminated, dilution with cleaner water is about the only solution. 

Given that we can expect this problem to get worse, we must redouble our effort to keep nutrients out of the water.  We can’t control the water temperature nor the hours of sunlight, but we can do something about the nutrient loading in our surface waters.  Unless we do more, we can expect there to be more problems with water quality in Iowa.

Mark Rasmussen

Conservation Learning Lab: Implementation of Cover Crops at Small Watershed Scale

Matt Helmers, director, Iowa Nutrient Research Center, shared the results of three years of water quality monitoring data after cover crop implementation during the Iowa Learning Farms webinar on Wednesday. The Conservation Learning Lab (CLL) project, started in 2016, posed the question, “Can high levels of cover crop implementation and reduced tillage be obtained on a small watershed scale, and water quality improvement documented accordingly?” The project focused on small watersheds—between 500 and 1,300 total acres in size.

Two pilot watersheds were chosen in Floyd County and Story County. These watersheds were chosen based on their size and that they had existing Conservation Reserve Enhancement Program (CREP) wetlands that provided baseline water quality monitoring data. This allowed for the comparison of water quality before and after conservation practice implementation and to a similarly sized control watershed that did not implement conservation practices. The figures above show the adoption of cover crops and strip-tillage in the two pilot watersheds for the CLL project.

The results of the study indicated that, to date, there has not been a noticeable reduction in nutrient loss at the small watershed scale due to the implementation of cover crops within the watershed. This may be because the entire watershed area was not treated with cover crops and a higher rate of adoption may yield noticeable water quality benefits. There may also be some lag time between implementation and noticeable results, which emphasizes the importance of continuing to monitor the results over several years. Growth of the cover crops is another factor that may impact the water quality benefits, as shown in other research, and may be the critical factor in this study. Some fields in the study were seeded with rye, while others were seeded with oats and it expected that oats will have less of an impact on water quality.

To learn more about this project, watch the full webinar!

Join us next week, on Wednesday, March 10 at noon, for the webinar, “Cropping System Diversification is a Path to Greater Sustainability,” presented by Dr. Matt Liebman, professor of agronomy and H. A. Wallace Chair for Sustainable Agriculture at Iowa State University (ISU).

Hilary Pierce

Nutrient Retention Capacity of Newly Restored Wetlands in Southwestern Ontario

During the webinar on Wednesday, Bryan Page, research biologist with Ducks Unlimited Canada, shared the first year of results investigating the nutrient retention capacity of newly restored wetlands in the Canadian portion of the Lake Erie watershed. In 2016, the US and Canada adopted a goal to reduce phosphorus in Lake Erie by 40% and wetlands were identified as natural infrastructure to help protect downstream water quality. The goal of this project was to assess the nutrient retention capacity of newly restored wetlands and provide a quantitative value to determine if wetland restoration should be used as a best management practice to help restore and protect Lake Erie water quality.

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This project measured all of the phosphorus and nitrogen species, rather than just total phosphorus and nitrogen, to allow for a greater understanding of nutrient retention and how biologically available the nutrients that were not retained are. Some species are more biologically available than others, making it important to consider the species when assessing nutrient retention capacity. The project assessed eight newly restored wetlands in southwestern Ontario, which had an average age of 4 years, average basin area of 0.33 hectares, and average contributing area of 16.4 hectares.

To learn more about this project and the first year results, including a breakdown of the different phosphorus species, watch the full webinar!

Join us next week, on Wednesday, February 24, for the webinar “Silvo-what?: Exploring Opportunities for Livestock with Silvopasture Management” with Ashley Conway, PhD, PAS, assistant research professor at the University of Missouri Center for Agroforestry.

Hilary Pierce

February 17 Webinar: Nutrient Retention Capacity of Newly Restored Wetlands in Southwestern Ontario

The Iowa Learning Farms webinar on Wednesday, February 17, will highlight research being done on the nutrient retention capacity of newly restored wetlands in Ontario, Canada.

Wetlands have been identified as natural infrastructure to help protect downstream water quality. However, wetland drainage has resulted in widespread loss of wetlands across the rural working landscape of southwestern Ontario, Canada. Bryan Page, research biologist with Ducks Unlimited Canada, will report on the first year of results investigating the nutrient retention capacity of newly restored wetlands in the Canadian portion of the Lake Erie watershed.

“In settled areas of Canada, up to 70% of our wetlands have already been destroyed or degraded. As they continuous to disappear, so too do the many benefits they provide,” said Page. “Newly restored wetlands retain nutrients on the landscape and help protect our lakes.”

Page received his B.Sc. majoring in Environmental Science and his M.Sc. in Chemistry both at the University of Manitoba. Since he joined Ducks Unlimited Canada’s Institute for Wetland and Waterfowl Research in 2008, his research has focused on the behavior of nutrients in restored, constructed, and intact wetlands across the prairie pothole region and southwestern Ontario.

Webinar Access Instructions

To participate in the live webinar, shortly before 12 pm CST on February 17:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

    Or, go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923

    Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

A Certified Crop Adviser board-approved continuing education unit (CEU) has been applied for, for those who are able to participate in the live webinar. Information about how to apply to receive the credit will be provided at the end of the live webinar.

Hilary Pierce

Around the World in 80 Bioreactors

Attendees of the Iowa Learning Farms webinar on Wednesday joined Dr. Laura Christianson, assistant professor, Department of Crop Sciences, University of Illinois, for a “stay-cation” tour of bioreactors around the world. Denitrifying woodchip bioreactors are promoted in the U.S. Midwest to clean nitrate from tile drainage, but they are also being tested around the world for a variety of applications.

Denitrifying woodchip bioreactors are a practical and flexible technology. They involve routing tile water through a bed of woodchips and often do not require land to be taken out of production. Bacteria use the woodchips as a carbon source and, through the process of denitrification, convert the nitrate in the water into nitrogen gas. The use of bioreactors is driven by the local context, needs, and goals, and the practice can be adapted as needed.

Stops on the tour included Denmark, Germany, Spain, Iran, and Madagascar. In Denmark, the local goal is to remove nitrogen and phosphorus from agricultural drainage water and the bioreactors are paired with wetlands to address excess nitrogen and phosphorus. A stop in Germany showed how bioreactors can be used in drainage ditches to remove nitrogen, an idea that has also been trialed in Illinois and Belgium.

In Spain, desalination of groundwater for irrigation led to the concentration of nitrate in the brine and on-farm desalination systems were banned after a eutrophication event in the nearby saltwater lagoon. Woodchip bioreactors have been proposed as a course of action to denitrify the nitrate-rich brine from the desalination process. In Iran, bioreactors are being used to treat nitrogen in their irrigation and drainage effluent. In Madagascar, bioreactors are being used to treat human fecal sludge using locally sourced filter materials.

To learn more about how bioreactors are being used around the world, watch the full webinar!

Join us next week, on Wednesday, January 27 at noon, for the webinar “The Iowa State Rural Drinking Water Survey: Some Preliminary Results and Insights” presented by Gabriel Lade, assistant professor of economics, Macalester College.

Hilary Pierce

The Cost and Benefits of Agricultural Water Conservation: An Economist’s Perspective

Our webinar on Wednesday featured Wendong Zhang, assistant professor and extension economist at Iowa State University, who presented an economist’s perspective on the costs and benefits of adopting agricultural water conservation practices.

Zhang shared research done in the Western Lake Erie Basin, where an integrated model was used to quantify the changes that might occur as the result of conservation practice adoption. This model involved the research done by economists, hydrologists, and ecologists. With these combined frames of reference, it is possible to begin to quantify the costs and benefits of certain policies and come up with some policy recommendations.

The webinar also featured survey results, from both the Lake Erie area and Iowa, which help to describe attitudes toward water quality and harmful algal blooms. The survey in Lake Erie found that anglers were willing to pay more per trip for in exchange for one less mile of boating through harmful algal blooms to reach their fishing sites. The survey in Iowa, of the general public and farmers, found that half of the general public and 30% of farmers think that algal blooms are very harmful. The survey also asked respondents about their familiarity with the Iowa Nutrient Reduction Strategy and what policies they support to reach nutrient reduction goals.

To learn more about the costs and benefits associated with conservation practice adoption, the Western Lake Erie Basin example, the survey results in Iowa, and the relationship between land ownership and conservation practice adoption, watch the full webinar here!

Join us at noon on Wednesday, December 16, for our final webinar of 2020: “Perennial Groundcovers for Achieving Soil & Water Conservation with Large-Scale, High-Yield, Row Crop Production,” presented by Cynthia Bartel, research scientist at the Iowa State University Biomass Cropping Systems Lab.

Hilary Pierce

Nutrient Reduction Progress at Iowa Wastewater Treatment Facilities

The Iowa Learning Farms webinar on Wednesday discussed the progress that has been made by Iowa’s municipalities and industries toward reducing point source pollution reaching Iowa’s waterways. Adam Schnieders, water quality resource coordinator with the Iowa Department of Natural Resources (DNR), shared information about the progress to date, after eight years of implementation.

Iowa’s largest communities and industries have a significant role to play to help meet the state’s nutrient reduction goals. Understanding that role and the progress to date paints a clearer picture of how the many facets of Iowa’s Nutrient Reduction Strategy fit together and work today. Schnieders shared some background information about how far Iowa has come in terms of water quality, and the importantce of wastewater treatment facilities integrating nutrient removal technology into their operations.

The data from 1992 to 2013 in the chart above is an estimate that is based on population growth and increased flow at the wastewater treatment facilities. With the finalization of the Iowa Nutrient Reduction Strategy, total nitrogen and phosphorus annual load began to be measured at the facilities. Although there appears to be a sharp increase after 2013, this is likely due to the limitations of the previously estimated loads. Now that the loads are being measured, progress toward the goals of the strategy can also be measured.

To learn more about the nutrient reduction progress at Iowa’s wastewater treatment facilities, watch the full webinar here!

Join us on Wednesday, November 11 at noon for the webinar “Finding the Right Fit for Soil Health Practices” presented by Dr. Abbey Wick, associate professor & extension soil health specialist at North Dakota State University.

Hilary Pierce

November 4 Webinar: Nutrient Reduction Progress at Iowa Wastewater Treatment Facilities

Iowa Learning Farms will present a webinar at noon Wednesday, November 4, which will assess the progress made by Iowa’s municipalities and industries toward reducing point source pollution reaching Iowa’s waterways.

Iowa’s largest communities and industries have a significant role to play to help meet the state’s nutrient reduction goals. Understanding that role and the progress to date paints a clearer picture of how the many facets of Iowa’s Nutrient Reduction Strategy fit together and work today.

In 2013, the Iowa Nutrient Reduction Strategy called for significant nitrogen and phosphorus reductions from Iowa’s largest municipal and industrial wastewater treatment plants. The strategy laid out unique policy approaches to achieve these ambitious reductions. During the webinar, Adam Schnieders, water quality resource coordinator with the Iowa Department of Natural Resources (DNR), will discuss the progress to date, after eight years of implementation.

“I hope participants take away an appreciation of the magnitude of the lift Iowa’s communities and industries are undertaking to meet the point source goals of the Iowa Nutrient Reduction Strategy,” said Schnieders, who is responsible for management and coordination of clean water programs and policies for the DNR. “These efforts are resulting in significant progress not only toward nutrient reduction at Iowa’s wastewater treatment facilities, but also in partnerships and collaborations with farmers to help each other improve Iowa’s water quality for a variety of mutual benefits.”

Webinar Access Instructions

To participate in the live webinar, shortly before 12 pm CDT on November 4:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

    Or, go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923

    Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

Hilary Pierce

Prairie Strips – Saving Soil, Cleaning Water, and Creating Wildlife Habitat

The final practice included in the Whole Farm Conservation Best Practices manual is prairie strips. These areas of perennial vegetation address three main resource concerns (soil erosion, nutrient loss, and wildlife habitat)

Prairie species have stiff stems and deep roots that slow down water, allow it to infiltrate, and filter out sediment and nutrients. Patches of native perennial vegetation create valuable habitat for a wide variety of birds, insects, and mammals.

Prairie strips can be placed around the edge of a field, within the field, alongside or perpendicular to waterways, and in terrace channels. To provide erosion control, improved water quality, and wildlife habitat, a minimum of 10% of the field should be converted to prairie. Prairie strips should have a minimum width of 30’ and be spaced at intervals that work with your farming equipment.

Check out the decision tree below to see if prairie strips can work for you!

Prairie flowers and grasses take time to establish, typically requiring two to three seasons of establishment management. Annual and perennial weeds grow quickly and can outcompete prairie plants in the first two growing seasons. Mowing prairie is an essential management practice that must be done during the first year whenever the height of the vegetation reaches twelve inches. Mower height should be set to four to six inches.

This helpful graphic can help identify which seed mix is right for your field.

Be sure to join us for two prairie strips events coming up this summer:

July 9, 1pm CDT – Virtual Field Day: Prairie Strips – Small Footprint, Big Impact

July 29, 12pm CDT – Webinar: Tim Youngquist, STRIPS Farmer Liaison

Find all our upcoming virtual field days and webinars on our Events Page.

Liz Ripley

June 24 Webinar: Environmental Performance of Wetlands Receiving Non-Point Source Nutrient Loads: Benefits and Limitations of Targeted Wetland Restorations

Iowa Learning Farms will host a webinar on Wednesday, June 24 at noon about the potential targeted wetland restorations have to reduce agricultural nutrient loads.

William Crumpton speaks to a water quality field day group at a CREP wetland in Pocahontas County

Over the past 15 years, over 90 wetlands have been restored through the Iowa Conservation Reserve Enhancement Program (CREP) with the explicit goal of intercepting and reducing non-point source nitrate loads. William Crumpton, Professor at Iowa State University, will summarize results from 15 years of work on Iowa CREP wetlands, including nutrient removal, GHG emissions, and hydrology. The research presented in this webinar is one of the largest and longest running projects of its kind and helps to clarify the potential benefits and limitations of targeted wetland restorations. The research methods are also being used to monitor the impact of in-field practice changes through the Conservation Learning Lab project.

“The Iowa Nutrient Reduction Strategy includes a wide range of in-field and off-field practices, but will likely require restoring thousands of wetlands targeted to intercept and reduce nitrate loads from cultivated cropland,” said Crumpton, who studies wetland processes and functions, including the dynamics of energy flow and nutrient transformation in wetlands, the fate and effects of agricultural contaminants in wetlands, and the role of restored and constructed wetlands in watershed hydrology and water quality.

Wetland restored to intercept and reduce nonpoint source nutrient loads from approximately 950 hectares of cultivated cropland in Palo Alto County, Iowa

“I hope participants will better understand the effects of targeted wetland restorations on water quality and hydrology and thus appreciate the potential benefits and limitations of this practice in Iowa’s agricultural landscapes,” Crumpton said about Wednesday’s webinar.  

To participate in the live webinar, shortly before 12:00 pm CDT on June 24:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

    Or, go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923

    Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

A Certified Crop Adviser board-approved continuing education unit (CEU) has been applied for, for those who are able to participate in the live webinar. Information about how to apply to receive the credit (if approved) will be provided at the end of the live webinar.

Hilary Pierce