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.
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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.
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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.
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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.

Earthworms serve as Indicator of Soil Health

A friend of the farmer, gardener, and angler alike, the earthworm may help to unlock the secrets of the soil by serving as an early indicator of soil health!  Anecdotally, farmers have expressed benefits to using cover crops and noted improvements to their soil, but quantifying changes in soil health can be complex to measure (and require years of intensive sampling). That’s where earthworms come into play!

Thanks to funding from a USDA-NRCS Conservation Innovation Grant, the Iowa Learning Farms team is studying the common nightcrawler, Lumbricus terrestris, and investigating its population dynamics in agricultural ecosystems.

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In particular, we are conducting midden counts at seven sites across the state (6 on-farm demonstration sites, 1 research site), all managed as a no-till corn/soybean rotation.

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Within that system, we are evaluating earthworm populations on side-by-side strips with and without cereal rye cover crops.  Read more about the study in our earlier blog posts Guest Blog: Digging for Worms and Midden Madness.

What have we found?

The midden counts conducted in June 2016 indicate that on each site, strips with a cereal rye cover crop have comparable or higher earthworm counts than those without a cereal rye cover crop …

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Looking at all sites together across the board, we see statistically significant differences between the strips with a cereal rye cover crop and those without. Based upon this preliminary data set, we are seeing 38% more earthworm middens with a cereal rye cover crop!

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If you’d like to learn more, I just gave a webinar earlier in the week on this topic. The archived webinar can be viewed on the Iowa Learning Farms webinar page (along with all of our previous webinars). Click on the November 16 webinar to view Earthworms and Cover Crops: Unlocking the Secrets in Soil!

Ann Staudt

This material is based upon work supported by the Natural Resources Conservation Service, U.S. Department of Agriculture, under NRCS Conservation Innovation Grant 69-6114-15-005.

Cover crops key to N retention + soil health, especially before soybeans

How can we increase nitrogen retention and soil health in Iowa’s corn and soybean cropping systems? There is not just one single quick fix, but Dr. Mike Castellano, William T. Frankenberger Professor of Soil Science and Associate Professor in the Department of Agronomy at Iowa State University, made the strong case for cover crops in last week’s Iowa Learning Farms webinar.

Castellano framed the webinar with a discussion of nitrogen budgets. As he put it, we don’t typically think about financial management without a budget – nutrient management is the same way! He then explored the potential of cover crops, especially cereal rye, to aid farmers in retaining nitrogen (via the cover crop plant biomass) and building soil organic matter. Watch the full archived webinar on the Iowa Learning Farms website: https://connect.extension.iastate.edu/p6kfk1qr4te/.

OR, if you’d like the CliffsNotes version, here are the Top 5 key take home points that jumped out at me…

cc-top5takehomepoints-iiAgain, you can check out the full presentation on the Webinar Archives page of the Iowa Learning Farms website.

Save the date…
The next Iowa Learning Farms webinar will be Wednesday, October 19 at 1:00 p.m., featuring our own Dr. Matt Helmers. He will be addressing common questions and misconceptions regarding cover crops, drainage, and more … think Mythbusters meets water quality! It’s sure to be a lively conversation.

Ann Staudt

 

Research Rocks!

Hi! I am Emily Rehmann, and I am one of the high school interns for Water Rocks! and Iowa Learning Farms this year. I will be a freshman at Washington University in St. Louis next year, and I am excited to start a new adventure there.

MeetTheInterns-EmilyThis is my second year interning with Water Rocks!, and while I enjoyed a second season of counting middens and attending fairs with the Conservation Station, I also wanted to try something new: data analysis. I had already experienced collecting water samples in the field from lysimeters, and now I wanted to take it further and see the results of the project and finally the implications of the results and the effects that they could have.

In the most recent blog post, Getting Dirty and Getting Samples, Mary described how the water samples from lysimeters are collected. Where she left off, Jessica, another high school intern and my sister, and I come in.

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The Rehmann sisters out and about with the Conservation Station — Emily is on the left and Jessica (who blogged earlier this summer) is on the right!

We have been working on analyzing the lysimeter project data from 2014 and 2015. Lysimeters collect groundwater samples, which are sent to the lab and analyzed for nitrate. The Iowa Learning Farms team is comparing the amount of nitrate in the subsurface water for corn vs. soybeans, and single cover crop vs. a cover crop mixture vs. no cover crop.

There are five sites where the Iowa Learning Farms team has collected water quality data for three years now: ISU Research Farms at Lewis, McNay, Crawfordsville, Kanawha, and Nashua. Each site has 24 plots (and thus 24 lysimeters), with 12 plots each for corn and soybeans. Within each cropping system, there are three treatments: plots with no cover crops, plots with a single cover crop (oats before corn; rye before soybeans), and plots with a cover crop mixture (oats, hairy vetch, and radish before corn; and rye, rapeseed, and radish before soybeans).

 Data are collected about eleven times per year from each lysimeter (from approximately April through November, as the weather allows). This all adds up to a lot of data to analyze–almost 800 samples per year!

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We had ten of these big spreadsheets, plus summary sheets, by the end of the process!

Jessica and I compared the lysimeter results from one plot with itself throughout the year, from one plot with a certain treatment to other plots with the same treatment, as well as comparisons between treatments. We also looked at precipitation data and the volumetric water content at 12 and 24 inches deep in the soil, measured at each site (from Iowa State Agclimate Automated Weather stations). We lined up the data from the lysimeters with the precipitation and volumetric water content data at each site to look for patterns and correlations.

Analyzing data was a fun and challenging experience. It was fun to figure out how what would be interesting to look at and compare, and how to best present the data. As we worked through the data, we kept coming up with more ideas for what to do with it and what graphs to make.

Our preliminary results indicate a positive water quality benefit comes from using a cereal rye cover crop ahead of soybeans. Cover crop mixtures can also help, but so far, across multiple sites, we have found that having a single species cover crop of rye ahead of soybeans is the most effective treatment for having a low amount of nitrates leaving the field. Preliminary results from Kanawha are shown below as an example. Since I do not know what a statistical difference between measurements would be, I cannot claim any definite results of the data yet.

Kanawha Preliminary ResultsThe water quality trends were less clear with corn. While a single species cover crop (oats) is also the most effective for corn, it is far less effective than rye is for soybeans. The cover crops used ahead of corn (oats, hairy vetch, and radish) all either die off over the winter OR yield very little spring growth. The biggest difference in the soybeans was the use of cereal rye and its winter hardiness — the spring cover crop growth made a huge difference in terms of water quality benefits! As the rye on the soybean plots has more to time grow in the spring, it uptakes more nitrate. Corn is planted earlier in the season, so if rye were growing prior to corn, it would have to be terminated earlier, yielding less benefit for the nitrate uptake by the cover crop.

Ideally, the amount of nitrate leaving the field (represented by the water that a lysimeter collects) would be low. Nitrate is most useful on the farm field, as it is dangerous in high concentrations to humans and pollutes water. Depending on the final results of the data, this research could potentially be used to show how and which type of cover crops are most effective in holding the nitrate in place without letting it move into water sources.

IowaNutrientReductionStrategyThis research and its results are important for water quality across the state of Iowa. The Iowa Nutrient Reduction Strategy aims to reduce nutrients in water coming from point sources, like wastewater treatment plants, and nonpoint sources, like farms. A high concentration of nutrients can cause hypoxia, a condition of an area of water that cannot support marine life because it does not have enough oxygen. Hypoxia is a problem in the Gulf of Mexico, and currently the states along the Mississippi River have (or are working to develop) nutrient reduction strategies to help solve this.

This research is made more relevant with the current lawsuit between Des Moines Water Works and three Iowa counties. The Des Moines Water Works uses the Raccoon River for their half million consumers, and they want the amount of nitrates coming from farms in the counties to decrease.

Farmers can make a huge impact on the amount of nitrate in water. I attended a meeting of the Ames City Council in the spring, and the Water and Pollution Control Administration presented to the Council. They could put $36 million into reducing nitrate leaving their facility, but there would be little overall effect. Since farms contribute 92% of the nitrogen load, while municipalities only contribute 8%, we need to consider how much focus there is on reducing the contribution from the point source pollution sources in the municipalities as well as on farms. The research that we are doing will hopefully help show farmers that cover crops are a great way to reduce the amount of nitrate leaving their fields, while also helping to build soil health and protect our soil from erosion.

Overall this internship has been very influential in what I am interested in. I am undecided on what I would like to major in at WashU, but I know that I would like to continue studying science and the environment, including taking a class on environmental science. I care about protecting the water, soil, and climate, and this internship has helped me to realize that.

Emily Rehmann

Let it GROW, let it GROW!

The mild fall and winter gave cover crops across the state a great start. Now it’s time to begin thinking about plans for spring management and termination. However, when preceding soybeans, hold off on cover crop termination as long as possible… later spring termination dates can offer outstanding environmental benefits!

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recently released study by Iowa State University describes the impacts of winter cereal rye cover crop termination dates preceding a soybean crop. Side-by-side trials were carried out in which the cereal rye termination date was varied – the early termination date coincided with termination before planting a corn crop, while the later termination date was delayed three weeks (one day before planting the soybean crop). Researchers found amazing differences in those extra three weeks of growth!

KeyFindingsISU Associate Professor of Agronomy Mike Castellano summarized the project’s findings as follows:

“At the present time, we can say with confidence that we can retain a lot more nitrogen in the system and lose less to the environment with increased biomass production. In the short term, that’s a great benefit for water quality challenges. In the long term, adding that biomass and keeping that nitrogen in the system will build soil health.”

Read more about this Iowa State University Extension and Outreach project and its findings at Research Shows Extra Cover Crop Growth Prior to Soybeans Provides Benefits.

Ann Staudt

Cover Crops: Spotlight on Grasses

The benefits of cover crops are undeniable: helping to protect from soil erosion during the “brown” months, uptaking nutrients that would otherwise be vulnerable to leaching, forage value for livestock, and, over time, helping to build soil organic matter. Cover crops can be readily integrated into corn and soybean cropping systems, as farmers are doing on hundreds of thousands of acres across Iowa. However, up front there are a number of important management considerations that must be taken into account:

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This blog post will focus on the first question above. There are three major types of winter cover crops used in Iowa: brassicas, grasses, and legumes. Over the last few weeks, we’ve introduced the “Top 10” cover crop species in Iowa, and we’re in the process of highlighting each of those in individual blog posts. So let’s get the low down on using grasses as winter cover crops!

When considering grasses as cover crops, there are wide variety of species to consider:NSRW_Rye_and_other_Grains

  • Cereal Rye
  • Oats
  • Winter Barley
  • Sorghum Sudangrass
  • Winter Triticale
  • Winter Wheat
  • Annual Ryegrass

Grasses are the most abundantly utilized type of cover crop in Iowa, offering many benefits to the user. First and foremost, the ease of establishment in the fall is a definite plus! Grasses can be successfully established via a variety of seeding techniques, including drilling, broadcast seeding, overseeding, and aerial seeding. With sufficient moisture for germination, they tend to quickly establish a nice green carpet across the surface of the field, while also establishing an extensive root system underground.

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While they do not grow a taproot that helps break up compaction like the brassicas, the quick-growing grasses have a more fibrous root system with outstanding abilities to hold soil firmly in place, anchor corn and soybean residues in the field, and promote water infiltration. Further, the grasses like to scavenge vulnerable nitrogen in the soil profile. Two cover crop grasses are featured in the Iowa Nutrient Reduction Strategy, with cereal rye and oats offering nitrate-nitrogen reduction rates of 31% and 28%, respectively.

Grasses tend to produce large amounts of residue. Depending on the grass species chosen, some will winter kill (e.g. oats) while others are winter hardy (e.g. cereal rye, winter wheat, winter triticale), offering the opportunity for additional biomass growth in the spring. Another benefit offered by winter hardy cover crops is the potential for helping with weed suppression in the spring as the cover crops can outcompete weeds for resources including light, moisture, nutrients, and space.

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For these overwintering cover crops, they must be terminated in the spring prior to planting your corn or soybean crop, whether that be via herbicide (e.g. glyphosate), mowing, tilling, or rolling. If using a glyphosate herbicide, the general recommendation for termination is 14 days in advance of planting to minimize adverse impacts on the following corn crop.

To the best of our knowledge, Iowa Learning Farms and Practical Farmers of Iowa have the longest on-farm cover crop research and demonstration project going on in Iowa, investigating the use of cereal rye as a winter cover crop across the state. In 25 of the 28 site-years of this study, farmers experienced no adverse impacts to corn yield following a cereal rye cover crop. The three instances in which corn yield was reduced by the cover crop occurred only in the first two growing seasons of the trial (2009 and 2010). Farmer inexperience with terminating cover crops or adjusting the planter to plant into the cover crop residues could have contributed to the yield losses in these instances. Want to dig in deeper? Full results of this ongoing study (through Year 6) can be found in the document Winter Cereal Rye Cover Crop Effect on Cash Crop Yield.

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Cost is always an important consideration in evaluating conservation practices on the farm, and even more so with the tighter margins that farmers are facing today. Grasses are a big plus in the cover crop world as they offer a significantly lower cost in comparison to other cover crop species.

How about seeding rates, seeding dates, and other considerations? Check out the USDA-NRCS’s recommendations in Cover Crops: A Guide for Iowa Producers and Cover Crop Recommendations from Practical Farmers of Iowa. Another excellent resource is the Midwest Cover Crops Council webpage, which includes information on a variety of cover crop research trials as well a robust cover crop selector tool.

In summary, cover crop grasses are versatile, well-tested across the state of Iowa, and offer numerous benefits to the producer. As our friends at Practical Farmers of Iowa like to say, “Don’t Farm Naked!

Additional Cover Crop Resources:
Cover Crops in Iowa: A Quick Guide (Iowa Learning Farms)
Iowa Learning Farms Cover Crop Resources page
Cover Crops: A Guide for Iowa Producers (USDA-NRCS)
Cover Crop Recommendations (Practical Farmers of Iowa)
Cover Crop Business Directory (Practical Farmers of Iowa)
Overview of Nonlegume Cover Crops (SARE)
Managing Cover Crops Profitably: Third Edition

Ann Staudt