Webinar highlights cover crop, water quality connections

In case you missed it, this past week’s Iowa Learning Farms webinar offered an excellent overview of the research findings related to the potential of winter cover crops to reduce nitrate leaching in corn and soybean cropping systems. Dr. Tom Kaspar, plant physiologist with the USDA-Agricultural Research Service, shared results from numerous studies that show the ability of cover crops to reduce nitrate concentrations and loads in tile drainage water.

The press headlines about nitrates and water quality are seemingly ubiquitous, and Kaspar provided solid data that help to paint a complete picture of the challenges and opportunities. Our land uses have changed dramatically, and over the past 60-70 years, our cropping systems have likewise changed dramatically with significant reductions in small grains, hay and perennial vegetation.  With corn and soybeans having a 7-month brown gap when they are not actively uptaking nutrients, that leaves a significant amount of time with nutrients vulnerable to leaching.

However, Kaspar’s research clearly demonstrates that cover crops help transition that brown gap to a green gap, providing the ability to “capture” nutrients in the soil that would otherwise be vulnerable to leaching loss. One of Kaspar’s long-term research studies in central Iowa found that rye cover crops in a corn-soybean cropping system reduced nitrate concentrations in tile drainage water by 57%. Additional studies by Kaspar and collaborators around the state found nitrate reductions of anywhere from 20% to 40%. This variability is expected, with different amounts of cover crop growth, weather, rainfall, soil types, tile systems, and field histories.

Kaspar also pointed out that it takes quite some time for nitrate to move through the system – there is a noticeable lag effect.  For instance, Kaspar and collaborators found that nitrate concentrations in subsurface tile drainage continued to decrease through the summer, long after spring cover crop termination.

Check out the full webinar, Lessons Learned from Using Cover Crops to Reduce Losses of Nitrate for 15 Years, on the Iowa Learning Farms webinar archives page.  And to hear more perspectives from Dr. Kaspar, tune in to Episode 06 of the Conservation Chat podcast!

Ann Staudt

Why the delivery scale?

When it comes to monitoring water quality, there are quite a number of factors to consider: What are you monitoring for? How is land utilized within the targeted area?  How, when, where, and for how long will water samples be collected? Under what flow conditions? The scale at which you monitor really makes a difference!

The plot scale is valuable for looking at the impacts of specific in-field management practices. Plot scale (or field-scale) monitoring is where most of the pollutant export and delivery data come from that informed the Iowa Nutrient Reduction Strategy. Treatments can also be easily replicated on the plot scale. However, it’s challenging to properly scale up plot-level measurements to the area of practice implementation to truly assess water quality impacts across landscapes and with multiple practices.

Monitoring on the watershed scale allows us to look at the collective impacts over a much larger land area.  For instance, watershed-scale monitoring provides a broad picture of water quality challenges and aids in the identification of impaired waters. When monitoring on the watershed scale, measurements inherently include what’s happening on the land (field scale practices), plus field-to-stream transport, plus in-stream processes (bed and bank processes).  It certainly provides a comprehensive look the big picture, but you can’t “sort” out the different contributions of what’s happening in-field versus in-stream.

In between these two lies the delivery scale.  Delivery scale monitoring occurs at the point where water is delivered to a creek or stream. For instance, with drainage research, this would be the point where the tile main surfaces and water empties into a stream. In a nutshell, the delivery scale reflects the direct water quality impacts from an agricultural area, minus the potential confounding effects of in-stream processes like bed and bank erosion. Here at the Iowa Learning Farms, we’d argue that this is truly a sweet spot for looking at the impacts of specific conservation practices.

You need to monitor at the delivery scale if you want to know specifically what the agricultural impacts are.  That’s exactly what we’re striving towards with the Conservation Learning Labs project.

Within a small watershed area (several hundred acres), can we get a substantial percentage of producers adopting a conservation practice, like cover crops, and then measure corresponding water quality improvements at the delivery scale?  Modeling suggests so, and this project will quantify what nutrient load reductions are actually realized thanks to large scale, targeted adoption of cover crops.

Cover crops were seeded for the first time in fall 2017 within our two Conservation Learning Labs project sites.  Stay tuned for results as we look at the water quality (and soil health) impacts of substantial cover crop adoption on the delivery scale!

Ann Staudt

On-the-Ground Experience with Cover Crops

“What’s building organic matter worth to you?”

For Prairie City, IA farmer Gordon Wassenaar and tenant farmer Will Cannon, it’s worth using no-till and cover crops on every single one of their 1300 acres of cropland.  In a field day hosted by Iowa Learning Farms, Jasper Co. NRCS and SWCD, Wassenaar and Cannon shared their perspectives on cover crops and how they can be very successfully integrated into corn and soybean cropping systems.

Wassenaar, who has farmed for over 50 years, stated that he first got into cover crops for the purpose of protecting the soil from erosion. He started with cereal rye, broadcast seeded from an airplane.

As time has gone on, Wassenaar’s reasons for using cover crops have evolved from simply erosion control, to improving the structure and functioning of the soil — raising soil organic matter, aggregate stability, and water holding capacity. Cannon commented that on top of that, another big benefit is feeding the biodiversity of the soil, like the beneficial mycorrhizal fungi, all while growing a healthy crop.

Timing and seed-soil contact are two big factors with establishing successful cover crop stands, and it’s a balancing act between the two. Aerial broadcast seeding (or interseeding with a high clearance vehicle) allows for a larger window of time for fall growth, while drilling provides greater seed-soil contact. Today, Wassenaar and Cannon have moved to drilling all of their cover crops, ideally getting them in the ground 24 hours or less behind the combine.

When asked about the financial considerations of cover crops, Cannon responded, “We’ve got to be willing to be a little creative and inventive to make it work.”  And they certainly are.

Cannon outlined several approaches they are taking to minimize costs and improve efficiencies in their operation:

  1. Shop around for cover crop seed.
    Compare prices with different cover crop seed houses in order to get the best bang for your buck. Wassenaar and Cannon are even considering growing their own cover crop seed down the road.
  2. Consider your seeding techniques.
    Aerial broadcast seeding and custom planting carry a significant cost.  Cannon explained that they have moved to seeding all of their acres now with a drill, which has provided greater seed-soil contact, and thus improved the seeding efficiency in terms of the number of seeds that actually grow (they’ve subsequently optimized/reduced seeding rates accordingly).  They are also saving dollars through the use of a smaller 120hp tractor and a cover crop drill that was bought used.
  3. There are a lot of good programs out there that can help.
    Take a look at the conservation programs and personnel on the federal, state, and local levels that can help out.

With years of experience implementing conservation practices of no-till and cover crops, Wassenaar reflected on how much the technology advances make conservation readily doable today.

“Back in the day, we plowed because we didn’t have planters that could plant into high residue. The equipment is so good today, that now we can plant into just about any residue.  … With cover crops out there, it’s almost like planting onto a mattress.”

Wassenaar is clearly passionate about conservation, and left field day attendees with the following thoughts:

“I don’t know any other way you can farm and save your soil than with no-till and cover crops.  … I’m convinced that if Iowans take care of their soil, the soil will take care of Iowa.”

Ann Staudt

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

Cover Cropping on the Lobe

Last evening, a group of 40 area farmers, Soil & Water Conservation District commissioners, and a nice delegation of ISU students from the Ag & Biosystems Engineering department gathered up at Gilmore City, Iowa for a conservation field day hosted by Iowa Learning Farms. Located between Humboldt and Pocahontas, in the heart of the Des Moines Lobe, the Gilmore City research site is home to some of the longest running research in the state on nutrient management and drainage water quality. Last evening’s field day focused on conservation practices that could be utilized in-field (emphasis on cover crops) as well as edge-of-field (bioreactors, saturated buffers, and wetlands).

Kicking things off were father-son duo Bob and Jay Lynch, who farm just outside of Gilmore City. The Lynchs have been long-term ridge tillers, and in recent years, have largely transitioned to strip tillage. In addition, they began integrating cover crops into their corn and soybean operation in 2012, and they have continued to increase cover crop usage since then. With five plus years of cover crop experience under their belts, Bob and Jay shared some words of wisdom and lessons learned with field day attendees.

 

Benefits of Cover Crops
Bob and Jay Lynch see soil health as the biggest reason to use cover crops. Bob commented, “To see the real benefits of cover crops, you need to go below the ground surface. I go out in my fields where I had rye, and take a shovel out there – the biologicals in the soil are a big deal. I hope I get an earthworm in EVERY handful of my soil! The cover crop roots give them something to eat for much more of the year. In addition to the earthworms, you have all of the other beneficial microbes, too.”

The “feel” of the soil is improved with cover crops, as well. The Lynchs spoke about cover crops giving their soil “a really nice spongey-ness.” The benefits of soil aggregation are there, too, with a cover crop – Bob referenced that the ground would come apart just like cottage cheese with a rye cover crop!

While the Des Moines Lobe is known for its rich, fertile soils, cool temperatures can pose a challenge. The Lynchs commented that cover crops help to moderate soil temperatures, and those results are consistent with data collected from the research plots at Gilmore City, as well.

The Lynchs have also seen some weed suppression benefits with cover crops – when the rye gets knee high in the spring, they’ve seen its potential for blocking out/reducing the abundance of some competing spring weed species.

 

Fall — Cover Crop Seeding
Aerial application of the rye cover crop has resulted in the best cover crop stand for the Lynchs. They emphasized that fall growth is a function of light availability, so the amount of crop canopy cover will be a big factor with the cover crops starting out.

With adequate moisture, rye cover crops will germinate quickly and begin their fall growth. Here is some emerging rye at the Gilmore City research site, just five days old!

 

Spring – Cover Crop Termination
With rye and other overwintering cover crop species, spring termination is necessary ahead of planting your row crops. The Lynchs prefer to terminate their rye via chemical in the spring. For the greatest effectiveness, Bob and Jay have found success in separating out herbicide application into two passes – even on the same day — applying glyphosate first to begin the rye termination process, then following with the pre-emergence residual herbicide.

While rolling, roller crimping, and tillage are also possibilities for cover crop termination, they require very particular conditions for success, and as Bob puts it, “It you try to till rye, you’re just making it mad … and then it comes back with a vengeance!”

 

Spring – Planting into Cover Crop Residue
When rye is growing ahead of corn, the Lynchs presented two options for termination timing: plant your crop the same day you terminate your rye, OR it needs to be dead for 14 days before planting corn.

With abundant cover crop growth, they emphasized that planter settings should definitely be taken into consideration. When planting soybeans into rye residue, the Lynchs recommend that your soybean seeds be planted using similar settings as if you were planting corn. If you use the same bean setting as you would without cover crops, you run an increased risk of the bean seeds sitting on top of the surface.

 

Management Matters
Bob and Jay concluded, “With cover crops, it all comes down to management. What works with YOUR individual farm?

 

Wetlands in the Spotlight
The evening field day concluded out at a CREP wetland just a few miles from Gilmore City, sited specifically for nitrate removal. It was a stunning end to the field day as the sun dropped lower and lower on the horizon!  The beauty of the wetland and its ability to benefit water quality clearly piqued people’s interest, as the questions and conversations continued even after the sun went down.

Ann Staudt

Exploring whether cover crop mixtures make sense on Iowa farmland

Last week I had the opportunity to attend the Soil and Water Conservation Society’s 72nd Annual Conference in Madison, Wisconsin.  In addition to attending some great sessions, meeting fellow conservationists, and exploring Madison, I participated in the Conservation Innovation Grant Showcase poster exhibition.  On display were early results from our cover crops mixtures project that began in 2013.

NCIGCoverCropsPoster-170721

 Some preliminary observations from the study: 

  • Achieved more biomass from the single species (oats or rye) than mixtures
  • Oats and rye resulted in the majority of biomass from the mixtures
  • Cereal rye was the only species to over-winter consistently
  • Generally lower pore water nitrate concentrations following rye and mixture of rye, radish and rapeseed

As we continue to analyze the data collected, the project indicates:

  • Cereal rye and oats establish readily and provide the most biomass growth when seeded on their own.
  • Cover crops can offer some water quality benefits, reducing nitrate concentration in pore water.
  • Rye and oats provide the best biomass return on seed investment! Single Species are the way to go in Iowa for corn and soybean producers.

Be sure to subscribe to our blog and check back for updates on the project, including analysis on crop yields.

Liz Juchems

 

 

The Nutrient Reduction Strategy: Creating A More Resilient Iowa

Have you ever fallen in love with a new car at the dealership and wanted to take it home until you look at the sticker price? Well, as I travel around Iowa, it seems like folks are pretty enthusiastic about the Iowa Nutrient Reduction Strategy (NRS) until they hear the “sticker price,” i.e. the scale of practice implementation and cost.

NRS Goals_3-24-2017

One example scenario to reach the nitrate-N reduction targets of the Iowa Nutrient Reduction Strategy includes 60% of corn-soybean and continuous corn acres having cover crops (~12.5 million acres), 27% of all agricultural land being treated with a wetland, and 60% of the tile-drained acres being treated with a bioreactor.

For wetlands, it was assumed that each wetland (10 acres of wetland surface area with 35 acres of buffer) treats 1,000 acres of agricultural land, which would result in approximately 7,600 wetlands for this scenario. For bioreactors, it was assumed that each bioreactor treats 50 acres of subsurface-drained land, which would total approximately 120,000 bioreactors in Iowa alone.

See what I mean – quite a sticker price!

BioreactorInstall_HamiltonCo_IA Soy Assn_Christianson_credit

But, while the scale of implementation and costs associated with reaching the NRS goals seem daunting, it is important to recognize the additional benefits that could come from pursuing nutrient reduction such as the economic benefits of cleaner water as well as the employment and labor opportunities to implement the various strategies.

Throughout the Midwest, discussions have begun on resources needed to implement the various state nutrient reduction strategies. While this is encouraging and exciting, most of the discussion has focused on the resources needed to implement the practices. There is very little discussion of the labor needed to successfully scale up the practices.

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I believe that for large-scale implementation of the NRS to be successful, we need to make the necessary investment in people. We need trained individuals that can work with farmers and landowners on implementing these practices. We need them both in the private and public sectors. Developing and delivering programs and classes that can train individuals to promote and assist in NRS practice implementation is crucial if we are going to make significant progress on reaching our nutrient reduction goal. There will be a significant increase in job opportunities for individuals who are trained and willing do this work.

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I firmly believe that if we accelerate the rate of practice implementation, we will see numerous small business opportunities throughout rural Iowa to site, design, and maintain these various practices and provide technical assistance to farmers and landowners.

 

It is a win-win for our state. Yes, it is a big investment, but it could stimulate our economy and make for a more resilient Iowa in every way.

Matt Helmers

Matt Helmers is an Iowa Learning Farms team member and Professor of Agricultural and Biosystems Engineering at Iowa State University. To hear more about implementing Iowa’s Nutrient Reduction Strategy, listen to Matt’s Conservation Chat with ILF Program Director Jacqueline Comito.