Grass species most popular cover crops among Iowa farmers

Grasses, brassicas, legumes – oh my! With so many cover crop species to choose from, how does one decide?

One way is to look at what the producers in your area are using and observe how well those species will help reach the goals you have for your land. Here are some examples of cover crops by group:

  • Grasses = cereal rye, oats, wheat, triticale, barley
  • Brassicas (plants producing a tap root) = radishes, rapeseed, mustards
  • Legumes = red clover, crimson clover, hairy vetch, peas

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To help identify what cover crop species are being used across the state, we asked our 2017 field day attendees.  Responses to our 2017 Field Day Evaluation Report are similar to our conclusions of what works best in our cover crop species research projects. Grasses are the best choice of cover crops for a corn/soybean system. Cereal rye was the mostly widely used species, with 85% respondents listing it as what they seeded in 2017. Reported brassica and legume usage is down overall compared to 2016 data.

Cover Crop Species

For those looking to get started with cover crops, we recommend the following:

Oats Before Corn & Cereal Rye Before Soybeans

These cover crop species are relatively inexpensive, readily available and easy to establish. Oats will winter kill whereas cereal rye is winter hardy and requires spring termination. That is why we recommend using it before soybeans to provide the best opportunity for first time cover croppers to learn how to manage the cereal rye and minimize negative yield impacts.

Liz Juchems

Farmer Profile: Ben and Andy Johnson

Ben and Andy Johnson_cropCLLThe Johnson brothers farm in Floyd County where they grow corn and soybeans and manage a ewe flock and feeder lamb operation. The duo are no strangers to conservation and trying new practices. They began no-tilling soybeans over fifteen years ago and have nearly ten years of experience strip-tilling corn. Other conservation methods they have employed on their farm include buffer strips, prairie CRP, pollinator habitats, field windbreaks, a pheasant safe program and cover crops.

Ben began using cover crops in 2013 when a wet spring delayed planting on hundreds of acres until it was too late to plant a cash crop. Not wanted the fields to remain empty all year, Ben planted oats and radishes for the first time. As to why he does it, Ben explained, “I want all my black soil still on top of my hills and not at the bottom of all of them, not in my road ditches and not in the Cedar River.” Within his no-till system for soybeans and strip-till system for corn, he found that using cover crops helped control erosion and improved organic matter and overall soil structure.


“I want all my black soil still on top of my hills and not at the bottom of all of them, not in my road ditches and not in the Cedar River.” – Ben Johnson


In 2016, Iowa Learning Farms approached Ben and Andy to be a part of a new Conservation Learning Labs* (CLL) project that is studying changes in nitrogen and phosphorus loss at the delivery scale. The Johnsons farm near an existing Conservation Reserve Enhancement Program (CREP) wetland in Floyd County that has measured water quality for about three years.

Using the CREP wetland monitoring system, the project will be able to measure changes in water quality after cover crops are planted in the project area over the next three years. The Johnsons agreed to participate in the CLL project, and in fall of 2017 they seeded cover crops on over 54% of the nearby research watershed acres.

Ben says, “The easiest place for somebody to start is no-tilling their beans. They don’t really seem to respond to tillage and it’s such a labor and money eater. That’s the biggest reason we switched. The most precious resource on my farm is time.”

Ben Johnson and his wife Amy have two sons, Jackson and Riley. Andy Johnson had his wife Abbie also have two young sons, Kyle and Carter. Ben was featured in our Conservation Chat podcast – listen to the episode to hear more about his operation and what drives his conservation ethic.

Julie Winter

*The Conservation Learning Labs project is funded by the Iowa Department of Agriculture and Land Stewardship (IDALS) and the United States Department of Agriculture – Natural Resources Conservation Services (USDA-NRCS) of Iowa.

Reducing Soil Erosion with Cover Crops: New Infographic

Iowa Learning Farms is pleased to announce the release of a new infographic publication titled Reducing Soil Erosion with Rye Cover Crops.

This visually engaging document highlights one of the biggest benefits of cover crops — the ability to significantly reduce soil erosion. Based upon long-term cover crop work conducted by Korucu, Shipitalo, and Kaspar, colleagues at the USDA-ARS National Laboratory for Agriculture and the Environment here in Ames, this study looks specifically at one of Iowa’s most popular cover crops, winter cereal rye.

The USDA-ARS team conducted in-field simulated rainfall studies on plots with and without cereal rye cover crops, and their findings are powerful in terms of quantifying erosion reduction – 68% less sediment in surface runoff water with a rye cover crop. Further, the amount of surface runoff water decreased, while the amount of water infiltrating was found to increase with the cover crop.

This study was conducted in central Iowa, in the heart of the Des Moines Lobe, on land with a 2% slope. Substantial erosion reductions were found here with rye cover crops — consider the benefits of cover crops to reduce erosion on more sloping lands across the state!

The full infographic is available as a free PDF download on the Iowa Learning Farms website. Clicking on the image below will also take you right there.

Ann Staudt

Do cover crops reduce phosphorus loss?

Cover crops are proven to reduce nitrate loss and decrease soil erosion on our agricultural landscape, but field scale studies on phosphorus loss are still in their infancy. Drs. Antonio Mallarino, Matt Helmers, Rick Cruse, John Sawyer with Iowa State University and Dan Jaynes with National Laboratory for Agriculture and the Environment have completed two years of a long-term field study and have released their preliminary results.

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The Hermann farm site south of Ames allowed Mallarino’s team to observe the effects of cover crops on phosphorus in the runoff study funded by the Iowa Nutrient Research Center.

The study is located at south of Ames on Iowa State’s Hermann Farm. The study includes replication on 12 areas ranging from one to three acres in a field that tested very high in soil phosphorus and is managed with a corn and soybean rotation. The study compares the use of winter cereal rye cover crops with and without tillage.

After two years, Dr. Mallarino observed:

“It is confirmed that cover crops reduce soil loss with tillage or no-till but mainly with tillage. Results also show that with tillage a cover crop reduces phosphorus loss. But it is not so clear that with no-tillage management a cover crop reduces phosphorus loss,” Mallarino said. “With no-tillage, there seems to be a small reduction in particulate phosphorus loss, but an increase in dissolved phosphorus loss.”
revisedherman-flowing-runoff-6-14-17

Surface runoff at the testing site is evaluated for total solids and several forms of nutrients.

Why the focus on dissolved phosphorus? The Iowa Nutrient Reduction Strategy is a technical, scientific and voluntary approach to reducing the loss of nitrogen and phosphorus to our waterbodies and the Gulf of Mexico that is home of a large hypoxic or dead zone.  Both particulate and dissolved phosphorus are part of the reduction goal, however dissolved phosphorus is responsible for algae blooms and has a visible impact on aquatic ecosystems.

Caution should be taken when drawing conclusions from only two years of data. Environmental factors play a role in nutrient dynamics with surface runoff, and during the two years of the study, major rain events at the test site had been minimal with very low runoff.

“We can’t make a strong conclusion from these two years of data. There needs to additional data collection from this site and better science-based projecting so we can encourage the addition of cover crops for the right reasons,” Mallarino said.

Click here to read the full article and learn more about project.

Questions about the project contact:

Antonio Mallarino, Agronomy, 515-294-6200, apmallar@iastate.edu

 

Liz Juchems

Can cereal rye cover crops suppress weeds?

A question recently arrived in my email inbox: What is the potential for weed suppression when using cereal rye cover crops?

To help answer the question, I reached out to Dr. Bob Hartzler, ISU Extension Weed Specialist and Professor of Agronomy, and Meaghan Anderson, ISU Extension Field Agronomist.


There is pretty good evidence that a thick, consistent Slide1stand of cereal rye can effectively suppress winter annual weeds.  In soybeans, rye with even cover and a lot of biomass (>4000 lb/ac) may provide some early season weed suppression, but generally the weeds will begin to emerge as the cereal rye breaks down.

Ann and I saw this first hand yesterday (photos below) when visiting our long term rye site in Page County to collection biomass samples. In the cereal rye strips only one or two field pennycress plants were found. However, in the neighboring strips without cover crops, the winter annual weed was thriving.

No evidence yet that cereal rye will help control perennial weeds, but it may help Slide2suppress perennial weeds germinating from seed or perennial rootstalks like dandelion, Canada thistle, field horsetail, etc.  Perennials normally develop from established root structures with a lot more energy reserves, so they are going to be tolerant of the competition from the cover crop.  If repeatedly used, cover crops could provide some suppression of things like dandelion and such.

Whether or not it provides some suppression or control of  resistant weeds would depend on whether those weeds fall into the categories listed above (early-season weeds or winter annuals) and whether the cover crop stand is consistent.

To keep up to date on weed issues, follow Dr. Hartzler on Twitter @ISUWeeds!

Liz Juchems

Cover crop researcher Tom Kaspar receives Spencer Award

Congratulations to our friend and collaborator, Dr. Tom Kaspar, on receiving the Spencer Award for Sustainable Agriculture yesterday!

Long regarded as the grandfather of cover crops here in the state of Iowa, USDA-ARS plant physiologist Tom Kaspar is certainly one of the leading voices on cover crops across the Midwest.  He was one of the “founding fathers” of the Midwest Cover Crops Council, and his collaborative work over the years has investigated and documented the benefits and challenges of cover crops in corn and soybean cropping systems, ranging from impacts on water quality, soil health, nutrient cycling, and more.

We are grateful to Tom for serving as a guest speaker at countless Iowa Learning Farms field days and workshops over the years, sharing his findings with farmers, landowners, and other ag partners across the state. We are also grateful for his efforts in guiding the work of the Iowa Cover Crop Working Group, including our long-term on-farm rye study and our study of earthworms and cover crops.

Kaspar has amassed years of experience investigating not only soil health and cover crops, but also connections with no till, minimum tillage, climatic variations, disease, pathogens, and more. To hear some great perspectives from the man himself, check out Episode 6 of the Conservation Chat podcast, in which host Jackie Comito talks cover crops with Dr. Tom Kaspar.

Kaspar was also featured in our August 2015 Iowa Learning Farms webinar, presenting on Reaching the Full Potential of Cover Crops in Iowa.  Stay tuned to the blog, as well — we’ll be highlighting some of Kaspar’s cover crop findings here in the next week or so.

In the meantime, congratulations to Tom for an honor that is very well deserved!

Ann Staudt

 

5 Lessons Learned with Rye Cover Crops

Here at Iowa Learning Farms, we’ve been working with cereal rye cover crops since 2008. That’s not nearly as long as our good friend and colleague Tom Kaspar with USDA-ARS, but we can certainly say that, with our partners in the Iowa Cover Crop Working Group, we’ve been exploring and promoting cover crops long before they were cool!

Our longest ongoing study involves the use of cereal rye as a winter cover crop in on-farm trials within corn/soybean cropping systems across the state of Iowa. Over the years, twelve farmers have participated as partners in this project, with each demonstration site featuring field-length replicated strips with a cereal rye cover crop as well as replicated strips without a cereal rye cover crop.

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In our eight years of on-farm cover crop demonstrations, what have we learned?  Here are our Top 5 takeaways regarding cereal rye cover crops:

1. Rye cover crops are largely yield neutral.
In the vast majority of this study (55 of 59 site-years), farmers found that a properly managed cereal rye cover crop had little to no negative effect on corn and soybean yields. Soybean yield actually increased in 7 site-years and corn yield increased in 2 site-years. There can be a learning curve up front, but in the long run, this study’s findings dispel the myth that rye negatively impacts crop yields (especially corn yields) in the following season.
yieldimpacts

2. Cover crops require active management.
Additional considerations/management factors when using a rye cover crop include seeding rate and method in the fall, and then cover crop termination and adjusting planter settings to accommodate additional residue in the spring. In the few cases of this study where crop yields were negatively impacted, farmers identified insufficient cover crop termination and improper planter settings as reasons for the few years where there were crop yield reductions.

3. Spring growth is key to realizing rye’s benefits.
Unlike winter wheat, oats, radishes and turnips, cereal rye survives over winter and continues its growth into the spring months. Large amounts of spring over crop biomass can be produced – variable to location and termination date.
springbiomass

4. Soil health is hard to define and even harder to measure.
Five years into the study, we found no measurable differences in soil health variables (soil organic matter, total carbon, total nitrogen, pH, infiltration and runoff) between the strips with and without the cereal rye cover crop at individual locations. A much greater intensity of sampling and additional time (years) may be required to quantify significant changes. Plus many of Iowa’s soils have relatively high levels of organic matter to begin with, so detecting very small changes can be challenging.

5. Earthworm numbers have increased with a cereal rye cover crop. Looking at the common nightcrawler (Lumbricus terrestris), our 2016 midden count data indicate a statistically significant difference of 38% more earthworms with a cereal rye cover crop. Earthworms can serve as tangible, early biological indicators of soil health.
earthworms

These findings and more will be highlighted at ISU’s Soil Health Conference coming up later this week. Stop by and see our poster, and let’s talk cover crops – we hope to see you there!

Ann Staudt

 

Additional information on our work with rye cover crops:

ILF Cover Crop Research webpage
Additional ILF Cover Crop Resources
Earthworms, Cover Crops and Soil Health

The Iowa Cover Crop Working Group is a collaboration of Iowa Learning Farms and the following organizations:

  • Practical Farmers of Iowa
  • Iowa State University Extension and Outreach
  • Iowa Dept. of Agriculture and Land Stewardship
  • USDA-Agricultural Research Service, National Laboratory for Agriculture and the Environment
  • USDA-Natural Resources Conservation Service
  • Midwest Cover Crops Council

Funding for this demonstration project has been provided by Iowa’s State Soil Conservation Committee, Iowa Department of Agriculture and Land Stewardship, Leopold Center for Sustainable Agriculture, Iowa State University Extension Water Quality Program, and NRCS Conservation Innovation Grant 69-6114-15-005.