Plant Cover Crops

Learning about the benefits of planting cover crops.

scavenge nitrogen

Fertilizing Cover Crops & Planting Legumes After Soybeans

If you spend any time at all in cover crop meetings, you may have heard that it’s a good idea to add 20-50# of Nitrogen per acre to your cover crop – if you don’t have a legume in the mix or you don’t have manure available. You also probably heard (or participated in) the grumbling that predictably starts from the crowd. Who wants to fertilize a crop that they will not harvest?

While it’s true that producers will not “harvest” the cover crops, they will have healthier cover crops which should lead to healthier soils and healthier profits.

Manure as the No-Brainer

Obviously if manure is available it is a smart move to put manure where you will have or already have cover crops.  We know from research that cover crops can hold as much as 90% of the nutrients from manure applications.

We have also know that where manure is applied without a cover crop being present (even if worked in) we can lose a significant amount of nutrients into ground water or as surface run-off.

What About Adding Commercial Fertilizer?

The Radishes on the left had manure applied and those on the right did not have any additional nitrogen applied.
The Radishes on the left had manure applied and those on the right did not have any additional nitrogen applied.

But, what if there is no manure to apply and for some reason you do not want to include a legume in your system?

Is it worth applying 50# of nitrogen to produce a cover crop?

Let’s look at what we think we know:

  • Pages 22-24 of Managing Cover Crops Profitably provide formulas to figure out the value of using cover crops as a green manure in a cover crop system –  whether with legumes, manure, or fertilized.

Look especially at the section on “Potential losses” to see that there can be nitrogen losses even in this scenario.

  • Cover crop experts say to count on 50% of the N captured or N produced by a cover crop to be available to the next cash crop.
  • It appears that adding a grass with legumes or brassicas will help “slow down” the release of the N in the spring making it more slowly released to the next crop.

 

Here is a photo of the Ingham County Michigan Cover Crop Plot. Where there was a legume in the mixture there was considerably more growth and earthworm activity
Here is a photo of the Ingham County Michigan Cover Crop Plot. Where there was a legume in the mixture there was considerably more growth and earthworm activity

What can we expect if we plant a cover crop and we don’t add more nitrogen?

How will that cover crop do?

I will utilize work that Dan Hudson did when he was an Extension educator in Ingham County Michigan in cover crop plots he planted back three or four years ago.

  • Radish tubers are considerably smaller and the roots appear to not be as deep  (I have not dug a root pit in this scenario).
  • Grasses have a more shallow root system in forage settings when fertility is lacking.
  • The cover crops were pale green.
  • The “hungry” grass cover crops had less earthworm activity than in the grass + legume mix plots.
  • “Hungry” radishes and turnips had much less tuber and top growth, thus sequestering less nutrients (one of their main functions).
  • Winterhardiness on cover crops is potentially not as good when the cover crop is undernourished.

What can we expect after soybeans?

Do we need a legume in the cover crop mix following the beans or is having a grass and/or brassica to sequester the N from the soybeans good enough?

Let’s investigate the difference between adding a legume to a cover crop mix following soybeans compared to planting scavengers only.  The charts are from our family farm trials.  The charts show the chlorophyll readings of the corn in the year following the soybeans (and then following a cover crop).

It is important to look at the “Y” axis as each chart is slightly different in how it shows the top reading.

When Austrian Winter Peas were added to a scavenger (Radishes) the chlorophyll readings were very favorable compared to the no cover crop check plot and plots with just scavengers.
When Austrian Winter Peas were added to a scavenger (Radishes) the chlorophyll readings were very favorable compared to the no cover crop check plot and plots with just scavengers.
Just like the peas gave us an advantage over the no cover crop check the crimson clover showed very favorably.
Just like the peas gave us an advantage over the no cover crop check  and scavengers, the crimson clover also showed very favorably.

 

While the Oats and Radish showed exceptionally favorable in the early part of the season the plot are "ran out of gas" as the corn was pollinating.
While the Oats and Radish showed exceptionally favorable in the early part of the season the plot “ran out of gas” as the season progressed.
Straight Winter Cereal Rye was impressive early season but also did not fare as well against the check as the mixes with legumes
Straight Winter Cereal Rye was impressive early season but also did not fare as well against the check as the mixes with legumes.

As we looked at the yield of the corn in these plots we saw a considerable difference – suggesting that even after soybeans we might want to add a legume to improve the corn yield the following year.

Yields from the different cover crop plots shown above were:

Check Plot                                    105.24 bu/ac

Winter Cereal Rye                      126.86 bu/ac

Oats and Radish                          138.79 bu/ac

Crimson Clover + Radish           153.99 bu/ac

AW Peas + Radish                        164.82 bu/ac

Conclusion

All indicators seem to point that adding manure, a legume, or additional N might very well pay off when planting a cover crop, even after soybeans.  However, adding a nitrogen source is not necessarily vital to having a successful cover crop system.  I would suggest that you try different scenarios on your own farm and in your own system and see what works best for you.

Cover Crop Field Day Set at Robison Farms

CISCO Seeds, Robison Farms, and Dougherty Fertilizer are sponsoring a Cover Crop Field Day and Root Dig at the Greenwood, Indiana farm. If you’ve not had an opportunity to see cover crops in a real life farm setting, this will be a great meeting for you . There will be multiple species available to look at and expert agronomists on hand to answer questions.

 

When:

Wednesday, November 30, 2011 from 2-4 P.M.

Location:

Corner of Five Point Road (300 East) and Main Street (Rocklane Road) east of Greenwood, IN

Contact:

If you have questions or need further information contact  Don Robison at donrobison@ciscoseeds.com or 317-357-7013

  • Rain or shine we will have a gathering (call if the weather is bad for “plan B”)

 

Cover Crop Field Day Highlights

Come see ten different mixes and/or species of cover crops in a large plot setting.
  • 1100’ lineal feet of cover crop plots
  • 10 different mixes or straight species shown
  • guaranteed weather! (not saying what kind)
  • working with NRCS, SWCD, and Dougherty Fertilizer
  • root digs (weather contingent)
  • Cover Crop Agronomists on hand for tours and Q/A sessions
  • See over 150 acres of various Cover Crops withing 1/2 mile of plots

 

Purpose of the cover crop field day

To see different species of cover crops in a real to life situation. This was a soybean field that had the cover crops applied over the top of the standing crop at roughly 50% leaf drop.

 

Species You Will See

 

  • Radishes
  • Turnips
  • Crimson Clover
  • Oats
  • Winter Rye
  • Annual Ryegrass
  • Austrian Winter Peas
  • Several Mixes including the above species

 

 

 

Directions:

From Indianapolis

  • Take I-65 South to Exit 99. Turn Left at end of ramp and travel 1.5 miles east to the plots

From Louisville

  • Take I-65 North to Exit 99. Turn Right at end of ramp and travel 1.5 miles east to the plots

From Columbus, OH

  • Take I-70 West to Indianapolis, follow 465 South to I-65 South to Exit 99. Turn Left at end of ramp and travel 1.5 miles east to the plots

From Terre Haute

  • Take I-70 East to Indianapolis, follow 465 South to I-65 South to Exit 99. Turn Left at end of ramp and travel 1.5 miles east to the plots

 

Just down the road we plan on digging another pit where Annual Ryegrass and Appin Turnips were applied after hog manure was knifed in after wheat.

Radish / Pea Mix Video

I have been visiting a  farm in eastern Whitley County Indiana over the past month and have seen a few fields of an Austrian Winter Pea/Radish mixture.  These fields were wheat fields that had dairy manure knifed into them after they had been harvested and deep tilled.  The video shows what a great stand the farmer got and the growth of the radishes!  We found one plant that had a 28+” deep tuber/tap root.  That’s how much was in the soil!  At 4″ below the soil surface I found where there had been quite a bit of compaction.  The radish was “crumpled” or “wrinkled” at the 4″ depth range.  Out of the 15 radishes we dug up only one radish had not bored through the compaction layer.

This GroundHog radish had a 28+" deep tuber/tap root.
The Austrian Winter Peas were growing very prostrate in this field. When I lifted the plants up they measure over 12" tall to up to almost knee high.
The radishes showed where there was compaction that caused some wrinkling of the tuber. The tubers grew through that compaction which shows the powerful ability of the cover crop radish.

Cover Crops and Manure are a Great Combination

Manure was captured by the annual ryegrass cover crop and was available for the following year’s corn crop.

During my past five years with the Midwest Cover Crops Council, I have heard cover crop experts say that “the farmer who has access to manure is the perfect candidate to use cover crops.”

I witnessed this truth up-close and personal this fall when visiting the Leman farm in NW Indiana.  The Leman family has a dairy farm and several acres of corn silage (the acres are usually planted to corn silage each year).  For years they fall applied manure to their fields with little nitrogen value being realized in the spring.

The soil is rather sandy and the manure had little to keep it in the soil root zone (but it had not been running off).  These past three years the Leman’s have been using cover crops in their corn silage fields with impressive results.  This year Scott Leman told me that he will “never stop” using cover crops because of the value they are finding.

Each year they leave sections of 30-36 rows in the silage fields that they leave for grain harvest.  In these areas they did not plant cover crops (until this year).

This fall Mark Perry, from CISCO Seeds, and I went to the farm with Randy Davis (Country Acres in Francesville, IN) and Curt Leman to see what difference we might find between where they had a cover crop planted (N-Vest® Soil Builder Annual Ryegrass Blend) and where there was no cover crop planted. The results were astounding…but not totally unexpected!

Where there was a cover crop there was much better plant health and bigger ears on the corn.  Curt was convinced that there would be a 20 bushel/acre or more advantage where there was a cover crop.

I did not take plant samples to send off to the lab to test forage quality on the silage, but I wish I had.  All I know is that there was more grain on a green stalk where they had the cover crop.  Where there was no cover crop the stalks were pretty dry nearly up to the ear and ~2” less grain per ear of corn.

The Lemans also cut back 50#/acre on their nitrogen application on their fields.  So, they saved $20+/acre on N cost and added 20 bu/acre on yield (at $4.50/acre) = PROFIT.  Save $20/ac — add $90/acre on yield = $110/acre. The seed cost was approximately $30/acre with $10 cost of application.

$110 – $40 = $60/acre added profit from using a cover crop.

Add in the benefits of cleaner water, less wind erosion, improved soil biology, increased soil organic matter, and less potential for manure run-off, I’d say that the Lehman’s are right in using cover crops each year.

The photos below show some of the value. Click on them to see a larger view.

These ears were typical where manure was applied but no cover crop was utilized.
These ears were typical from the area where the Lemans used cover crops. There was approximately 2” of “extra” grain on each ear where they had cover crops.
This photo shows the silage corn where there was no cover crop utilized. The stalks were “firing” up to the ears.
This photo shows Curt Leman in the silage corn where there was a cover crop utilized. The stalks were healthy and green.These stalks were approximately 30’ away from the stalks shown at the left.

Cover Crop Selection – What to plant after wheat or other cereal grains?

I was in a meeting yesterday and the gentlemen from SWCD asked me:

“What should we recommend for our producers to plant as a cover crop after the wheat comes off?”

After running through a number of scenarios I determined that I’d better make sure I don’t confuse folks with too many ideas.  So, here are a few scenarios that I hope you find useful.

If you want to scavenge Nitrogen and other nutrients, then a good choice would be Oats and Radishes mixed together.  This mix generally should be planted at 1 1/2 bu Oats and 2-5# of Oilseed radish/acre.  This mix also requires manure or around 40# N applied for it to be the ideal mix for this situation.  This mixture will die in the winter and provide excellent winter annual weed control.  Best planting time is Mid August…so you have plenty of time to get weeds killed and manure applied.

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Sudangrass and Sorghum-Sudangrass are excellent crops after wheat if you need animal feed.

If you have livestock to feed, other great nutrient scavengers to plant after wheat are Sudangrass, Pearl Millet, or Sorghum-Sudangrass. These summer annual grasses require 100+# of N or equivalent manure. Tonnage of 4 1/2 tons Dry matter/acre have been common in northern Indiana following wheat the past three years. These grasses are excellent soil builders as well. Mycorrhizae fungus find the roots of these plants a very good place to multiply and build soil structure.

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Oats and Radish Mixture following wheat. Hog manure was nitrogen source.
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When properly inoculated, Austrian Winter Peas are prolific producers of nodules (and nitrogen).
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Oilseed Radishes are "nutrient sorage facilities"! These big tubers take in significant amounts of nitrogen and other nutrients.

If you want to produce nitrogen and also scavenge nutrients as well, then an excellent choice will be Austrian Winter Peas mixed with Oilseed Radish .  This mixture works very well without the addition of additional nitrogen.  Count on the peas to deliver 60-120# of N and the oilseed radishes to keep most all of it in the top soil root zone. This mixture does a great job of controlling weeds.  The radishes will die in the winter and the peas will “probably” die too…depending on your location, planting time of the mixture, and snow cover.  If they overwinter they are easily killed in the spring.

If you are looking mainly for nitrogen production with a species that will winterkill, then choose cowpeas.  The past few years cowpeas have been very expensive to plant.  Be sure to check pricing and also be sure to inoculate the seed at planting time.  Sow 60-100#/acre of cowpeas.

If you want the nitrogen production with a crop that will overwinter, then crimson clover is a top choice.  Excellent new varieties have come on the market the past few years.  Be sure to inoculate this seed as well. Sow 20-25#/acre of crimson clover.

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Crimson clover planted after wheat is an excellent nitrogen producer.

There are several other options but these will certainly give you a good start in making selections.