Cover Crops: One Piece of the Puzzle in CLL Project

Cover crops are an important tool for helping keep soil, nitrogen and phosphorus in the field – instead of our water bodies. Because they grow outside the typical corn/soybean growing season, cover crops help reduce soil erosion and take up nutrients that could otherwise leave the field. It is also the most popular practice among our Conservation Learning Lab (CLL) farmer partners.

The CLL project is studying the impact of conservation practices implementation at the watershed scale in Floyd and Story County.  The conservation planning process within the watersheds has yielded cover crop contract enrollment of 675 acres and 1,081 acres, respectively, starting this fall covering 50-68% of the crop acres within the watershed.

Cover_crop_April_Berger_FarmThe farmer partners chose to seed either winter cereal rye and oats.  These grass species are easy to establish, relatively inexpensive and are the leading biomass producers in our cover crop research projects – keeping that soil covered (reducing the loss of phosphorus) and taking up nitrogen.

The Iowa Nutrient Reduction Strategy team reviewed cover crop research results from across Iowa and the Midwest and found that cereal rye and oats reduced nitrogen loss by 31% and 29%, respectively.  Similarly, the reduction of phosphorus when adding cereal rye is about 29%, primarily as a result of reduced soil erosion. According to our RUSLE2 calculations, a cereal rye cover crop added to a no-till system can reduce soil erosion by 30-80% and can be even larger when transitioning from a conservation tillage system.

Be sure to keep checking back as we will be providing updates as the cover crops are seeded this fall!

The 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.

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

Now Available! Evaluating Cover Crop Seeding Techniques Publication

Seeding Tech LocationsThe Iowa Cover Crop Working Group (ICCWG) has wrapped up a two-year study evaluating planting techniques for the successful establishment of cover crop mixtures and single species in Iowa. We are grateful to our partners: Hagie Manufacturing Company, famer partner Tim Smith, and Iowa State University Northern Research and Demonstration Farm.

Replicated cover crop strips were established in fall of 2014 and 2015 to compare three different seeding techniques:

Evaluation was completed through fall and spring biomass collection and crop yield. A no cover crop plot was included in the replications as a yield comparison check strip.

The mixtures species were selected based on the upcoming crop and their winter hardiness. Because the species seeds are different sizes, a goal of one million seeds per acre was used for seeding calibration to provide a fair comparison between treatments.

Seeding Mixtures

Oats and rye win the day

Results show that earlier seeding with the high clearance interseeder resulted in more cover crop biomass, both fall and spring, than the later seeding with a drill. For Iowa, oats and rye work better than any other species tested at this time. The single species (oats and rye) resulted in more total biomass than the mixtures providing better soil erosion protection. Oats and rye were also the predominant species in the mixtures, accounting for the majority of the biomass.

Seeding Tech Biomass

There are no statistical differences in corn or soybean yields across the different cover crop treatments and no cover check plots. This yield neutral response following a cover crop is consistent with a long term ICCWG cereal rye cover crop project now entering its ninth year.

The publication is now available online and at upcoming ILF field days.

This research project was made possible with a State Conservation Innovation Grant through the Iowa Natural Resource Conservation Service.

The ICCWG includes core members from: Iowa Learning Farms, Practical Farmers of Iowa, Iowa State University Extension and Outreach, USDA-Agricultural Research Service, Leopold Center for Sustainable Agriculture, Iowa Department of Agriculture and Land Stewardship.

Reducing Nutrient Losses While Building Iowa’s Soils and Economy

Today’s guest post is by Marty Adkins, Assistant State Conservationist for Iowa Natural Resources Conservation Service (NRCS), a member of the Iowa Learning Farms Steering Committee.

Iowa’s soils are globally precious and unique. These soils are the cornerstone of a vibrant and productive farming sector and make Iowa’s overall economy strong.  Protecting and building the productive capacity of Iowa’s soils is essential to Iowa’s future.  Happily, many of the same practices that help protect and build soils also have a positive impact on water quality.  This is especially true of cover crops, crop rotations that include small grains and forages, and no-tillage and strip-tillage planting.

Marty Adkins and his other passion in life; playing the ukulele.

The widespread adoption of cover crops will require increased availability of seed and seeding equipment.  There are new business opportunities related to the growing, cleaning, transportation, sales and custom planting of cover crop seed.  Iowa’s farm machinery industry can continue to design, build, sell and service equipment needed for cover crop seeding and management, and increased adoption of no-till and strip-till.

There are other farm business opportunities to consider when it comes to conservation farming practices.  Cover crops and extended rotations could provide more grazing for more livestock in more places, with more small-town businesses selling all needed goods and services to livestock farms.

In addition to increased economic activity in the farm and industrial sectors, there are other economic benefits to be gained from conservation practices.  An Iowa countryside that is green nearly all year-round, with the land covered and protected, would be a more attractive landscape for Iowa residents, and could attract visitors and new entrepreneurs.

Economic research shows that cleaner streams and lakes result in increased recreational opportunities (swimming, canoeing, boating, and fishing) and more tourism to towns and cities associated with these amenities.  More dollars stay in Iowa when Iowans vacation and recreate within the state.

The environmental benefits associated with better soil management are well documented.  But improved soil management can also contribute to Iowa’s economic well-being, now and long into the future.

~Marty Adkins

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.

Field day highlights cover crops & soil health

Well, the groundhog indeed saw his shadow yesterday, so we are in for six more weeks of cold weather. While the temperatures outside were certainly brisk, it was a great day to be inside learning some new perspectives on cover crop management, soil health, and even earthworms!

covercropssoilhealth-title

I was invited to be a part of a Cover Crop & Soil Health Field Day in Houghton yesterday, put on by the Lower Skunk River Watershed & Soil Health Initiative. Approximately 55 farmers, landowners, crop advisors, and NRCS staff from across southeastern Iowa and northeastern Missouri gathered together to spend the morning digging in with cover crops and soil health issues.

Dave Otte, of Green Valley Seed (Kahoka, MO) kicked things off by sharing his experiences with cover crops over the years, both in corn/soybean farming systems and as a “cattle guy.” He explained the many different benefits that he’s seen with cover crops, including soil health and quality (feeding the biology under the ground surface), water control (promoting infiltration), erosion control, moderating soil temperatures, nutrient management (creating, capturing, holding, and releasing fertility), weed suppression, and forage. He was also very open in discussing the challenges with cover crops, but emphasized that the benefits are well worth it. We were quite entertained by his analogy that cover crops are a lot like marriage. As he put it, “I’ve been married 40 years, and there have certainly been ups and downs. But the positives definitely outweigh the negatives!” I liked how he emphasized that going with cover crops will make you THINK more – rethinking your farm management in a positive way.

Rebecca Vittetoe, ISU Extension field agronomist in south central Iowa, was up next, helping the attendees think ahead to creating a game plan for cover crop termination in advance of planting in the spring. She shared a number of different termination options, ranging from mechanical means (like mowing, rolling, or roller-crimping) to chemical means (herbicide). It was very interesting to hear her discuss data from the University of Missouri Weed Science program regarding the effectiveness of different herbicides on different cover crops, and how much that effectiveness can vary with termination date. Lots of food for thought!

mizzou-ryetermination

mizzou-hairyvetchtermination

After a short break, NRCS soil scientist Jason Steele shared his wealth of knowledge on all things soil health, offering perspectives on what exactly soil health is, improvements in soil organic matter that can be realized with practices like no-till and cover crops, and the benefits of increasing water infiltration across our landscape. He also performed the Slake test, demonstrating aggregate stability and how healthy soils are “glued together” biologically.

Steele also offered some great analogies about how cover crops fit into our farming operations … “Cover crops are a lot like small children. For those of you that have small children (or have raised kids), you know that it takes patience and it takes time.”

And regarding earthworms and soil health, “It’s a lot like the movie Field of Dreams … ‘If you build it, they will come’ …  well, with earthworms, they’re probably close by in your fencerows. If you make them a home, they will come!”

That was a great transition, because I concluded the learning portion of the field day by sharing findings from our  ILF study of earthworm populations related to cover crops!  I highlighted the fact that we found 38% more nightcrawlers in corn/soybean fields with a cereal rye cover crop compared to those without, and how earthworms can serve as a tangible, early biological indicator of soil health. There were also questions earlier in the day about tenant/landowner relationships regarding the implementation of cover crops, so I also promoted our new Talking With Your Tenant publication series which offers tips for starting that conversation, as well as ways to potentially share the cost of implementing a conservation practice like this.

While we are certainly still very much in the throes of winter, take a look at these beautiful cover crops that I spotted while journeying through southeastern Iowa yesterday (Feb. 2)!  I’ll leave you with a few photographs from just south of Swedesburg in Henry County.

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Ann Staudt