The Chemistry of Burndown of Annual Ryegrass

Glyphosate is the most common herbicide used to control annual ryegrass. It’s very important to use a rate that is adequate. The minimum rate of glyphosate recommended for annual ryegrass is 1.25-1.50 lb a.e./acre with ammonium sulfate and surfactant in late March to early April. Use 1.75 lb a.e./acre if needed.

Glyphosate products vary in concentration and this affects application rate. Here are two application examples to provide the necessary 1.25-1.50 lb/acre a.e.:

  • A 41% glyphosate product containing 3 lbs/gal of a.e. (acid equivalent). Application rate should be 53-64 oz/acre
  • Roundup PowerMax is a 48.7% glyphosate product with 4.5 lb/gal of a.e. Application rate should be 36-43 oz/acre

While one burndown application should provide control of the annual ryegrass, growers should plan for two applications, especially if the initial spray conditions were cool

  • Consider using an herbicide with a different mode of action if re-spraying is needed (Research is currently testing alternatives to glyphosate and tank mixes with glyphosate to reduce the dependence on this important herbicide)

Even when annual ryegrass is small it requires full rates of herbicides to achieve control. Low rates will often stress the plant making it more difficult to control at a later date

  • In years with marginal weather conditions, or where the ryegrass is in the jointing stage, use a higher rate of glyphosate (1.75 lb a.e./acre) to help insure complete control. Using a full label rate once is preferred to split applications of a lower rate.

 

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Killing Annual Ryegrass Cover Crops Adds to Soil Organic Matter

Cereal rye is a great cover crop. Sometimes, however, the amount of biomass in the spring creates difficulty for drilling corn seed. The excess vegetation can impede proper planting and can also take moisture out of the soil that crops will need this summer.

Annual ryegrass doesn’t create as much biomass,The residual left by the annual ryegrass after burndown quickly decomposes into the no-till soil. It becomes food for soil critters and microorganisms. And the massive root network slowly decomposes too, building organic matter. The channels created by ryegrass roots become channels for corn roots. The combination of root channels and more organic matter allows better infiltration of rain. but it is important to spray the crop out in a timely fashion.

Corn roots in ARG 6-06 Starkey
Annual ryegrass, if let grow too long, can be more difficult to kill. And letting it go to seed is asking for trouble…nobody wants to contend with a cover crop that gets away.

Last week’s blog discusses the proper guidelines for applying herbicide to kill the cover crop. Here’s a linkto the management guide where those instructions are.

 

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Terminating Annual Ryegrass Effectively – the 1st Time

The first important step in controlling annual ryegrass used as a cover crop is the timing of the burndown.

  • It is best done when the plant is small, 6-9” in height, and preferably before the first node has developed. Typically, this happens in late March to late-April depending on weather and farm location.
  • Make sure the crop is actively growing, so as to optimize the uptake of the herbicide (glyphosate).
  • Daytime minimum temperature should be at 55 degrees (F) and above 60 is better. •  If night temperatures drop below 38, wait three days before spraying. • Soil temperatures should be above 45.

Early termination of the cover crop makes control easier and reduces the amount of residue into which you’ll plant corn or soybeans.

  • Early control also facilitates soil dry-down, allows for significant decomposition of annual ryegrass residue and release of nutrients for uptake by the corn or soybean crop.

Some growers have found it easier to plant into the annual ryegrass first and then apply a burndown. Warmer weather conditions improve glyphosate activity and planting into green vegetation has been successful, and is often easier than planting into a “half-dead” cover crop.

Warm temperatures and actively growing annual ryegrass plants are a must for effective control.

  • Use a thorough spray coverage using moderate spray pressure and a medium spray droplet size. Don’t use air induction spray systems or nozzles that produce coarse droplets.
  • The application rate should be about 8-12 gallons per acre.
  • Spray at least 4 hours prior to sunset to allow for maximum translocation of the glyphosate within the plant.
  • While one burn-down herbicide application often provides control of the annual ryegrass. Inspect the results and then be ready for a second application if needed. (If you use too weak an herbicide solution, it will make the plant more resistant and more difficult to control later.)
  •  Apply glyphosate at 1.25-1.50 lb a.e./a with ammonium sulfate and surfactant. Follow label directions carefully with respect to pH and mixing order. It is important when adding ammonium sulfate, buffering agents or water conditioners that they be added to the full spray tank of water and agitated for 3-5 minutes before adding the glyphosate. Additional NIS surfactant, if called for, is normally added last.
  • Weather conditions affect how well glyphosate controls annual ryegrass and a second application may be required.

 

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Time to Terminate Annual Ryegrass Cover Crops

The fields may already be clear of snow. You may already be noticing that the annual ryegrass or other cover crops are starting to show life. Watch carefully and be vigilant about terminating the crop before the grass reaches the “joint” stage.

Here are a couple of timely resources to help you figure out the timing, the right chemicals, the right dosage and whether or not you need to spray again. It’s best to get it right with the first application but there is a plan B should the first spray application not do the trick.

ARG burndown

Click here for a free management brochure about annual ryegrass.

Click here for a quick guide to successful burndown of annual ryegrass.

Click here to learn about the residual effect of herbicides on corn and beans.

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Making a Nitrogen Bank Account with Ryegrass as a Cover Crop

Here’s how Eileen Kladivco put it: Even with well-managed corn and soybean production, there is always some leaching of nitrate that originates either from residual fertilizer N or from the natural decomposition of soil organic matter. Our annual cropping systems are “leaky” because there are long fallow periods between crop maturity in September and the active growth of the next cash crop in May. Most of the net downward flow of water to the drains occurs precisely during this long fallow period, when there is nothing to take up the nitrate. 

IMG_0145 (2)

Eileen is an agronomy department professor at Purdue University, a well-regarded researcher and teacher about soil and making agriculture more profitable. She goes on to say that, Non-legume cover crops will scavenge or “trap” soil nitrate that would otherwise move out of the rootzone into tile drains or groundwater. Cover crops actively take up nitrate during a portion of that fallow season, reducing the losses that occur to tile drains and recycling the nitrogen for later use. To read her Full article – click here.

In another publication, the author talked about the biomass of cover crops. Basically, he said that more biomass generally means more nutrients and organic matter returned to the soil.

The “plant available nitrogen” (PAN) released from a cover crop depends on what cover crop you’re growing and when you terminate the cover crop. As the cover crop plant matures, more nitrogen gets stored in the stems, so in general it’s best to terminate the cover crop before it reaches that stage. With annual ryegrass, terminating it before it reaches 6 or so inches in the spring is important…both to take advantage of the nitrogen available but also to keep the plant from reaching the joint stage.

As soil organisms decompose cover crop residues, part of cover crop is released as carbon dioxide. The rest decomposes and contributes to the soil organic matter…as well as giving up the stored nitrogen for the corn or beans maturing in the same soil.

The high price of nitrogen has growers looking for way to be more efficient. Using annual ryegrass may provide 60-80 lbs of nitrogen per acre. This alone could more than pay for the cost of the seed and planting the cover crop. For more information on annual ryegrass and its capacity as a nitrogen sink, click here.

 

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Satellite Imagery Helping Cover Crop Productivity

GPS and satellite technology have given agriculture a big gift, one that keeps on giving. With precision farming, growers now plant and fertilize based on field data and guidance systems calibrated to deliver the right input to the right locations. Productivity increases faster than costs, or at least that’s the goal.

Even a decade ago, there were only so many satellites and they were expensive to access the data for personal use. But now, nanosatellites scarcely bigger than a lunch pail provide far greater coverage at a fraction of the cost. Their low orbits and high resolution cameras give accurate, full time coverage. More importantly, the type of data available allows for greater application of data synthesized from aerial and ground sources.

satellite image cropland

Remote sensing is able to detect variability in soil and crop conditions.High-resolution, “multi-spectral” photos help understand what’s going on in the fields, and help reduce crop inputs. Pest and weed control are easier and less expensive. Imagery and field data help growers schedule harvest to maximize yields.

The latest in a new array of these tools is a collaborative effort called OpTIS (Operational Tillage Information System). Combining satellite and various on-the-ground data gathering methods, growers can now access information that allows field-specific tracking of crop residue management, types of tillage and cover crop use and value.

OpTIS uses multi-spectral satellite imagery to measure wintertime vegetation on agricultural fields and combines this information with site-specific knowledge of crop rotations and cover crop management practices. Images taken throughout the year are converted to show estimated cover crop coverage, the amount of cover crop residue, the type or classification of tillage practice, monitoring seasonal changes in cover crop residue and compiling all this with data from the field, the watershed and the wider county level.

According to a presentation by Applied GeoSolutions, LLC, about the OpTIS system, “Proximal sensors and on-farm sampling are used to calibrate imagery interpretation, and hyper-spectral, biophysical models are used to understand the impact of various components of ground cover (vegetation, soils, crop residue, and shadow) on field reflectance.  Using these methods, USGS researchers can map cover crop performance at the watershed scale and improve the understanding of conservation outcomes associated with various cover crop management strategies. This information is used by farmers and conservation agencies to promote adaptive management of winter cover crop programs to maximize environmental benefits.”

In a pilot program last year, OpTIS was used in a small number of Indiana watersheds. Based on initial feedback, the program will broaden this season to more sites in that state as well as other sites in Ohio, Illinois, and Iowa, according to Dan Towery, whose work with the Indiana Soil Health Management project intersects with the OrTIS project.

Towery also said that the data available will help growers understand more about their varied soil types, help them gauge the impact of cover crops on building organic matter in the soil, and even better understand how to adjust management practices more accurately based on annual precipitation.

 

 

 

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Seeding Annual Ryegrass as a Cover Crop

Need…the mother of invention.

Since the beginning of the cover cropping boom, in the 1990s, innovators have been making continuous improvements to cover crop seeding technology.

Part of the drive to innovate was the need to extend the window of opportunity for the cover crop to survive. Seeding annual ryegrass after harvest didn’t reliably leave enough of a growing season to establish the crop before winter.

Late Summer or Fall Seeding

  • Aerial seeding allowed growers to put down cover crop seed while the corn was still in the field. The seed would germinate and establish as the harvest took place, opening up the annual ryegrass to fall sunlight and precipitation.
  • Highboy equipment was adapted to do the same thing as planes, and perhaps with a bit more accuracy
  • Lately, growers have been mounting air seeders on combines, in those locations where seeding at harvest does leave sufficient time to establish before freezing weather
  • This technique takes advantage of doing two things with one pass, saving precious time and money.

Spring Seeding

  • The practice of “inter-seeding” began in Quebec and has quickly taken off in the US. The idea, discussed previously on this site, involves seeding cover crops like annual ryegrass after the corn has reached about knee high (v 5 – 7). That gives the grass an opportunity to establish before the shade of the corn puts it into a kind of dormancy for the summer.
  • It seems that ongoing research has shown that too much shade can kill the grass. So the innovators are suggesting to plant a shorter variety of corn (less than 7′ tall at maturity) or plant the field at a rate of about 32,000 corn kernels/acre. That will give a bit more sun filtering through for the grass.
  • Once the corn is harvested in the late summer, the ryegrass – dormant for the summer – quickly resumes its growth before fall
  • This technique has an advantage over fall-planted cover crops simply because it has more time to establish before cold weather.
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Annual Ryegrass – At the Root of it All

The Dust Bowl crippled the Great Plains states in the 1930s and 40s because of poor soil management in the decades before that.

The mistakes made were partly because of economics – farmers were rewarded for expanding their acreage in order to satisfy the demand for corn and wheat to supply troops in World War I. But the mistakes were also due to the fact that most farmers did not understand the effect of plowing under the native prairie grasses to make room for cash crops. And, after World War II, the popular thing was to make use of the bountiful supply of anhydrous ammonia (high in nitrogen) for supplying the nutrients lost to oxidation and erosion.

Annual ryegrass is akin to those native prairie grasses in at least one respect: they all have very deep roots. And, as you know, it is the roots that protect the soil surface from erosion. Modern agricultural methods include cover cropping, which prevents nutrients from eroding off the property. No more waste of topsoil; less need for adding nutrient inputs to bolster anemic soil.

Corn roots in ARG 6-06 Starkey

The other key factor with annual ryegrass’ deep roots is that they seek moisture and nutrients in deeper soil. Roots grow to depths of 6 feet in some places. The benefit is that roots from ryegrass create channels for the corn and soybeans to follow. Once the cover crop is killed in the spring, the roots die and add to the organic matter in the soil, in addition to creating pathways for new rooting crops and infiltration of snow melt and rain.

The annual ryegrass website has tons of good information about growing this cover crop. There are videos, too, and you need only click here. Finally, No-Till Farmer magazine has an article that talks more about the benefits of annual ryegrass.

 

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Mike Plumer Gets Acknowledged for His Contribution to Cover Crop Science

At the recent National No-Till Conference in St. Louis, a number of people were acknowledged for their contributions to agriculture. Mike Plumer was among them, and his recognition is well deserved. If there is ever a candidate for the Cover Crop Hall of Fame, Plumer is it.

Mike Plumer

Mike has made a career out of helping others, whether as an Extension Agent, Natural Resources Educator, Agronomist or Crop Consultant. Even during his 34 years working for the University of Illinois, he was also farming his own land, researching and testing ideas on his own crops.

Since leaving the University, he has been at the forefront of cover crop innovation. It was he who managed the early field trials of annual ryegrass, when it astonished growers and academics about annual ryegrass’ deep rooting and compaction busting properties.

He started and continues to work with the Illinois Council on Best Management Practices. He was on the ground floor with the Midwest Cover Crop Council. He has helped thousands of growers learn quickly how to employ cover crops in various states, different climates and with many different soil properties. He has given selflessly to big and small audiences, from the Midwest to both U.S. coasts, and from  Austria to South Africa.

In recent years, as more government agencies and nonprofit environmental organizations began to recognize the value of cover crops, Mike was a consultant and patient guide in their steep learning curve. He has been a tireless advocate and champion of cover crops in whatever setting he finds himself.

With Mike’s consistent effort, the word spread quickly about cover crop benefits. From only hundreds of acres in cover crops during the 1990s when he began his push for use of annual ryegrass as a cover crop, the number of farms using cover crops has grown geometrically. Recent estimates indicate that between 2 and 4 million acres in the Midwest are planted in cover crops each year. The increases, year over year, indicate that the growth curve is not abating. SARE and the CTIC surveyed farmers and they said there was a 37.75 percent increase in cover crop acres from 2012 to 2013 alone.  And according to Practical Farmers of Iowa, the increase in cover crop seed flown onto to farmland grew 200 percent increase between 2010 and 2013.

But Mike has also been a keen observer of best practices and has continued to caution and educate people about making small steps to increase their chances of success. In a quote from a National Wildlife Federation publications on cover crop management, Mike said, “It’s important for farmers to have the right help when they are starting out with cover crops. Because cover crops require a totally different set of management skills to be successful.”

Congratulations, Mike. And thank you.

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How Hardy is Annual Ryegrass as a Cover Crop?

In the chart below, you can see color-coded bands that pertain to climatic zones. In the accompanying guide to growing ideal cover crops, the Pioneer and DuPont agronomists determined that annual ryegrass was not recommended for use above Indiana, except in Michigan surrounded by lakes Huron and Michigan.

Plant Hardiness Zone Map

But here’s the catch. If the extreme temperature and wind chills hit annual ryegrass uncovered, it can certainly kill it off, or knock it back significantly. What is key to know, however, is that if the plant has snow cover to protect it from the icy blast, it can survive winter perfectly well.

In southern Canada, Ontario and Quebec specifically, lots of farmers use annual ryegrass each year. Their usual snowfall almost guarantees a healthy winter for annual ryegrass. Farmers in Minnesota and North Dakota also find annual ryegrass a viable cover crop even with their harsh winters, again, because of adequate snowfall.

In the report’s other graphic, showing the attributes of different cover crops, it shows annual ryegrass as ideal for a variety of reasons, namely for scavenging nitrogen, busting up compaction, preventing erosion and building organic matter. Click here for more information on growing and managing annual ryegrass as a cover crop.

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