Tag Archives: nitrogen scavenging cover crop

Understanding the Nitrogen Advantage of Annual Ryegrass

Let’s review the facts about nitrogen, in the context of growing corn in the Midwest, and the connection to ryegrass as a cover crop.

One, corn needs a lot of nitrogen, and if corn is planted year after year in the same field, you will need to add nitrogen to bring the corn to harvest.

You already know that no-till will help stabilize the soil and help it regain its natural health. However, unless you plant a cover crop, you will continue to have to add a lot of nitrogen to feed the corn.

Secondly, it’s known that annual ryegrass “sequesters” nitrogen. As it grows, annual ryegrass absorbs available nitrogen from the soil and then sequesters, or stores, the nutrient in the foliage. When the cover crop is terminated in the spring, all that residual, stored up nitrogen is released. Annual ryegrass, because of its leaf structure, decays quickly in the spring, thus making its nitrogen available to the new corn as it begins to mature in late spring.

Lots of study has been done in the past 10 years about how much nitrogen is absorbed by annual ryegrass, and how much it can contribute back to the corn plants when the grass decays.

At best, the nitrogen that annual ryegrass adds back to the field substantially reduces the need to supplement nitrogen during the year. And, at a minimum, annual ryegrass reduces the costs associated with planting and managing a cover crop.

In an experiment studying annual ryegrass, Farm Journal Field Agronomist Ken Ferrie recorded per-acre costs for annual ryegrass and then calculated the value of the residual nitrogen left over in the spring, when corn was planted. the following graphic box indicates the costs/acre for seed, machinery, herbicide and application costs for terminating the ryegrass.

At the bottom of the graphic box, Ferrie estimates that the amount of nitrogen added back to the soil from annual ryegrass was $75/acre. That is an average and some will experience less, especially if you are just adding cover crops to your management repertoire. However, some farmers have experienced better than $75/acre return of nitrogen from their annual ryegrass cover crop.

So, according to Ferrie, “after subtracting the value of the nitrogen saved, the total cost of the cover crop was $5.75 per acre.” Not bad, especially when you then factor in the added benefits of cover crops: improved soil structure, increased organic matter, increased water infiltration, controlled erosion and recycling additional nutrients, like Phosphorus (P) and Potassium (K). This “recycling” occurs due to annual ryegrass’s deep roots, which helps corn to develop deeper roots to access P and K from deeper soil structure.

Phosphorus is a major component in plant DNA and RNA. Phosphorus is important in root development, crop maturity and seed production. Potassium is required so than more than 80 enzymes in the plant can be activated. K is also important for a plant’s ability to withstand extremes temperatures, drought and pests. Potassium also increases water use efficiency.

Finally, those who plant cover crops consistently experience higher corn yields, which translates into a profit to the pocket as well as to the continued health of farm acreage.

Earth Fix Boosts Production and Profit

More than a decade ago, it was becoming clear that runoff from farm acreage was choking fresh water flowing south from the Canadian border to the Gulf of Mexico. Satellite images, water testing and production declines in fisheries pointed to a pending disaster if agricultural practices were not modified. At risk, the health of millions who depend on clean water, as well as industries that depend on healthy water.

Cover crops were introduced in a dozen states that border tributaries to the Mississippi, as well as along that great stretch leading into the Gulf. Last year, the Environmental Protection Agency produced a report for Congress outlining the “successes” in that gigantic project. Here’s a link to a summary.

Here’s one small result, from efforts in Indiana:

The 2014 fall transect [study] estimated 1 million acres of living plant cover such as cover crops and winter cereal grains were planted on Indiana farms. The report also shows most Indiana farmers left their tillage equipment in the shed in the fall to protect their fields with harvested crop residues. Results for residues and undisturbed soil on harvested acres during the winter months include: 77% of corn acres, 79% of small grain acres, and 82% of soybean acres.

The fall cover crop and tillage transect occurred again in 2015, and according to the data, over 1.1 million acres of cover crops were planted in 2015, which is an increase of nearly 10 percent compared to the previous year and 225 times more coverage over the past decade. The fall tillage and cover crop transect will be conducted again in late 2016.

Related image

In addition to keeping pollution from entering watersheds, the practice of cover cropping also makes a healthier environment for soil to heal. That, in turn, makes corn and soybean production more profitable, even in years when drought or low commodity prices carves into profits.

Ryegrass and other Cover Crops – Benefits the Purse and the Earth

You have undoubtedly read, or experienced, the following effects by stopping cultivation, adopting no-till agriculture practices and then planting cover crops, such as annual ryegrass.

Saving on fuel costs by reducing the trips over the field
Reducing or eliminating soil compaction and fragipan layers
Preventing soil erosion
Conserving soil moisture
Protecting water quality
Fixing atmospheric nitrogen while reducing the need for nitrogen fertilizer
Reducing the need for herbicides and pesticides
Improving organic matter, soil porosity and water infiltration
Increasing the population of healthy microorganisms and earthworms
Increasing yields by enhancing soil health

In the last year, another benefit has come to light, based on the collaborative work of two men working on opposite sides of the Atlantic ocean. They claim that cover crops help to mitigate the effects of climate change.

Professor Jason Kaye (Penn. State) and Miguel Quemada (Technical University of Madrid) looked at the following things:

Cover crops lower greenhouse gases by increasing soil carbon sequestration and, thus, the use of less fertilizer
Cover crop vegetation also lowers the proportion of energy from sunlight that is reflected off farm fields.

This last point, according to Professor Kaye, “may mitigate 12 to 46 grams of carbon per square meter per year over a 100-year time horizon.” Click here to read a longer description of the article. Or, click here for the academic study itself.

Annual Ryegrass Plugging Through another Winter

While the temperatures plunge and the snow whirls, annual ryegrass top growth has been dormant for months. But under the freeze, the annual ryegrass roots continue to flourish, adding depth, girth and mass to a system that builds healthy soil in numerous ways.

The depth of rooting alone is a benefit, because it opens channels in the soil profile. Those channels, next spring and summer, will allow corn roots to seek deeper veins of nutrition and moisture. Even in a dry year, corn that goes deep will continue to thrive. And, with any normal precipitation, those root channels will help the soil absorb the rainfall rather than allowing it to run off.

Annual ryegrass has an appetite for nitrogen, too, so it becomes a storehouse of nitrogen when it grows. Then, in the spring, after it is killed with herbicide (before planting corn or beans), the nitrogen stored in the residue becomes a fertilizer for the hungry corn plants. And the massive root structure of annual ryegrass, when it is killed, that mass degrades and decomposes, increasing the carbon content and organic matter in the soil, giving worms and microbiological organisms a food source.

Because of annual ryegrass’ nature to sequester nitrogen, it’s place in the crop rotation allows you to lighten up considerably on nitrogen inputs.

For more information about annual ryegrass, why it’s beneficial and how to manage it successfully as a cover crop, you can check out this free four-page management guide. Or you can click here to view a series of YouTube videos on the subject.

Cover Crops – Production Boost is Only the Start

The Conservation Technology Information Center (CTIC) has been a champion of cover crops for many years, and the Oregon Ryegrass Growers Commission takes a wee bit of credit for that being the case.

Since the early 1990s, Oregon’s annual ryegrass growers have worked with Midwest farmers to prove the value of ryegrass for cover crops. Gradually, universities and nonprofits began to take notice. Cover crops were, until then, seen as a threat to crop production.

Now it appears – given proper management of cover crops – that there’s practically no end to the benefits to planting cover crops. And yet, less than 10% of farms use the practice. Sure, it took a century of tillage to prove the damage of that system; it will take a few more decades before cover crops are uniformly adopted.

Take a look at this article, that quantifies the monetary value of cover crops. You’ll be amazed, and perhaps inspired to try cover crops yourself.

And, if you want to learn more, check out this brochure from the folks that started the cover crop phenomenon – the Oregon annual ryegrass folks.

Carbon Sequestration and Annual Ryegrass Cover Crop Acreage

Conservation tillage, in the best sense, includes cover crops. In addition to enriching the soil, cover crops literally inhale carbon dioxide from the air and use it for plant growth. What isn’t used for growth is eventually released back into the soil.

According to the Conservation Technology Information Center (and the United Nations Food and Agriculture Organization). upwards of ONE THIRD of the carbon emitted in our world (from power plants and internal combustion engines) could be offset if farmers worldwide would all make use of conservation tillage, including cover crops.

Annual ryegrass, as a cover crop, is adept at absorbing carbon and storing it in its massive network of roots. When killed in the spring, the annual ryegrass residue (including the roots) releases its sequestered nitrogen to help fertilize the new corn and beans in the field. At the same time, the carbon in the cover crop is released into the soil, improving the ratio of organic matter and adding to the food source for soil microbiology.

Would Mother Jones be Rolling in Her Grave? Probably not.

Mother Jones (Mary Harris Jones) was loathed by many during her 90 plus years as a tireless advocate for middle class workers. In 1902, already 65 years old, she was named “the most dangerous woman in America” because of her championing of coal mine workers who wanted more safety, better wages and union representation.

So, given her Socialist and anti-corporate leanings, it was a surprise to see a big feature article this year praising the benefits of cover crops in a magazine named after her: Mother Jones.

The article looks at the benefits of annual ryegrass (they called it rye) in battling the polluting effects of farm runoff into Chesapeake Bay. The article quantifies the subsidy to farmers to plant cover crops (up to $90 per acre) but also quantifies the savings.

Check out the whole article here. Mother Jones article on Cover Crops

What is gratifying, other than the value that cover crops bring to agriculture, is the fact that farmers and environmentalists can agree on a lot more than they used to. In fact, environmental groups have become important allies when it comes to conservation tillage practices espoused by the ag industry.

Annual Ryegrass Seed Sources

Annual ryegrass is a tool for improving soil health and increasing crop yield. In fact, annual ryegrass is like the durable Leatherman tool – just one application to fix a lot of problems.

Annual ryegrass puts an end to erosion and the loss of precious topsoil through your tile system and into the nearby waterways. In doing so, you are improving water quality and air quality at the same time.
The cover crop has deep roots that break up compaction, accessing nutrients and moisture in deeper soil. During dry years, this helps keep corn from shriveling up in the heat, creating drought resistant plants.
Using annual ryegrass also boosts organic matter by providing lots of decaying roots in a more friable soil. More food for the critters that inhabit healthy soil.
Among other attributes, annual ryegrass also sequesters nitrogen available in the soil, helping conserve it for use when the corn needs it in the spring, after the ryegrass has been terminated. This saves you money on the amount of nitrogen you need to add during the year.

But like every tool purchase, the buyer must beware. Just as there are Leatherman copies that are cheaply made and don’t last long, annual ryegrass also comes in varieties that are better designed for the tough work of Midwest cover cropping systems.

Take a look at the list of growers and suppliers at this link. Do some research and, if you have questions, call those who grow and sell annual ryegrass seed. Many of them have invested countless hours and considerable resources in developing varieties of annual ryegrass that are hardy over the winter. That helps to keep something growing year round and prevents wind and water erosion.

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.

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.

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.