Tag Archives: nitrogen scavenger

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.


Annual Ryegrass Video Series – for beginners and intermediate cover crop users

soil pit2The experts said it back in 1998, that no-till and cover crops were a winning combination for corn and soybean growers. Ten years later, a series of videos were done to introduce the idea and bring basic understanding of the what and how of cover crops. Back in 2005, the idea that a cover crop could sink winter roots down to 50 inches or more was revolutionary in the ag industry. Today, the practice is becoming widespread in the Midwest. The videos stand up to the test of time, and continue to be a solid source of information.

In the first video segment, you can get a glimpse of the main characteristics of annual ryegrass, and a couple of its major benefits.

Root depth: “Better than a deep ripper, in terms of its ability to break up compaction,” said Dan Towery, of Ag Conservation Solutions, an Indiana consultant on soil health.”Far deeper than other cover crops,” said Mike Plumer a former university agronomist and pioneer in cover crop development in the Midwest.

Nitrogen scavenger: those who use livestock manure in the field benefit by having the nutrient stay in the field.
“Annual ryegrass is a great nitrogen scavenger,” said another cover crop pioneer in Indiana, Dan DeSutter, …keeping it in the field instead of sending it down the tile lines in the spring with runoff.”

If the videos are of some interest, perhaps you would also like more information about the science and the management of annual ryegrass. If so, click here for a free brochure. Or, click here for a library of information on the annual ryegrass website.

Cover Crops and Carbon Penalty

In a recent issue of Ag Web, sponsored by Farm Journal magazine, an article written by Darrell Smith covered some ideas and advice given by the magazine’s resident agronomist, Ken Ferrie. The following paragraphs caught my eye:

Cover crops can reduce corn yield by acting as weeds in the row and by tying up soil nutrients when they decompose. “If cover crop plants are allowed to grow in the corn row, the corn plants see them as weeds, and it creates stress,” Ferrie says. “Stress lowers yield potential. The longer weeds and corn plants grow together in the row, the greater the reduction in ear size. Even if you take out the weeds, or the cover crop, a few weeks later, the damage has been done. Yield potential has been lost, and you will never get it back.” 

He goes on to say, “Another source of stress on young corn plants is the carbon penalty. When cover crops are killed, the influx of carbon in the residue leads to a higher population of soil microorganisms. They temporarily tie up soil nitrogen and other nutrients, leaving corn plants to go hungry in the critical early weeks. If a cover crop has a high carbon/nitrogen ratio, the longer it’s allowed to grow in the spring, the more residue and the higher the carbon penalty.”

This seems to make sense until you look at a couple of basics:  In most cases, cover crops are planted in the fall,  just after harvest or, increasingly, when the corn is still standing but already matured. (An exception is the relatively experimental “interseeding” of cover crops in the spring, after the corn is about knee high).Thus, the planting of a cover crop in August or September or October would have no bearing whatsoever on yield.

It appears that he may have planted another cover crop in the spring, because the fall planting had winter killed. Then,because of the bad spring weather (2014), he didn’t plant the corn until the end of May, six weeks after normal. He planted into a relatively new cover crop which, of course, would compete for available nitrogen. Then, as it turns out, he didn’t put any ‘starter’ nitrogen on the corn when he planted, but instead waited until weeks later when he sprayed glyphosate to kill the cover crop.

When he concludes that the reason for poor yield was because of “carbon penalty” (residue from dead cover crops creating more microorganisms and thus tying up nitrogen) it may in fact be more due to the anomalies in his experiment that year.

In any case, it’s important to remember to give corn plants a boost of nitrogen when planting – somewhere between 30 and 40 units. And if you’re planting into an existing cover crop, make sure you add the N then, not waiting until you burn down the cover crop, perhaps a month later.


Good News and More News about Cover Crops

Climate Change photoIn next week’s UN Climate Change Conference, cover crops won’t be center stage but certainly will be part of the mix of popular go-to strategies for long-term global health.

Cover crops, including the ever-popular annual ryegrass, continue to gain credibility as a low cost boost for soil, water and air quality. Reducing runoff from agricultural fields, cover crops can help to improve Earth’s water quality. In the US, cover crops are already showing their value in reducing the problems in Chesapeake Bay, the Great Lakes and the Gulf of Mexico.

In addition, cover crops including annual ryegrass and crimson clover are seen as crucial allies in reducing the need for extra nitrogen in mono-crop systems like corn and soybeans. By sequestering (annual ryegrass) or fixing (clover) nitrogen in the soil, cover crops save money while not sacrificing production.

Whatever comes out of the Conference in Paris will be good news for those adopting new conservation strategies including cover crops. Whether good practices like cover crops are further incentivized or regulated, their use will be good for agriculture and good for the health of the planet.

Mike Plumer 2012 Report on Annual Ryegrass and Other Cover Crops

“Why has there been such an increase in cover crops in recent years?” asked Mike Plumer at the Oregon Seed League meeting yesterday.

  • First, it’s about capturing the nutrients in the field, keeping nutrients from running off during winter and spring months. In a normal year, there can be 90 lb/ac of nitrate available for annual ryegrass or another cover crop to take up. In 2012, because of the drought, there was probably well over 100 lb/ac in many places. With the cost of nitrogen going to $1500 – $2000/ton, it’s easy math to see why cover crops make sense.
  • “Cover crops can double your yields,” Plumer said. Though rare, in a terrible weather year like 2012, there were lots of instances where farmers more than doubled their yields with annual ryegrass and other cover crops. The secret is rooting depth. Without cover crops, corn roots starve out quickly as they hit compacted layers. With annual ryegrass roots penetrating to beyond 6 feet, they allow channels for corn roots to follow.

Plumer’s caution to the group was in terms of cover crop seed quality. “There are about 7 varieties of annual ryegrass that are hardy enough to weather a Midwest winter,” he said. Because of the popularity of annual ryegrass, however, seed provided to unwary Midwest farmers may not be among those seven varieties. Plumer said it would be a tragedy to flood the Midwest with seed that won’t grow well. His advice to buyer’s;  beware…and ask lots of questions about the source and variety of seed. His advice to seed growers: make sure you’re sending us varieties that will withstand Midwest winter conditions.


Burndown of Annual Ryegrass

In the next month, all that lush annual ryegrass will become history…as you’ll have to terminate the cover crop to make way for soybean and corn seeds. But “history” is a relative term…in fact, the residue of the grass will quickly decompose, giving the precious nitrogen it has stored up to the new plants.

Here’s a website with specific data about the proper way to burndown annual ryegrass.

While the dead foliage provides nitrogen for the corn and soybean sprouts during critical times in the late spring and early summer months, the roots produced by the ryegrass will also play an important role, in two ways. First, as the roots decay, they’ll provide organic matter for the soil, and nutrition for the bacteria, microbes and earthworms that help create healthy soil. Secondly, and nearly as important: the channels created deep into the subsoil by the annual ryegrass roots allows corn roots to sink equally deep, thus giving the crop a summer-long supply of moisture and nutrients deeper in the soil profile.

Especially in dry years, annual ryegrass cover crops will give your corn harvest a huge boost. Growers regularly find that cover crop acreage outperforms no-till and conventional tillage acreage by as much as 100 bu/ac!