Plant Cover Crops

Learning about the benefits of planting cover crops.

manure management with cover crops

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 Crops in Wisconsin – Full Speed Ahead!

This cover crop field was ready for harvest in late September 2012.

I took a new management position in May of 2012 with Wisconsin based Legacy Seeds, Inc.

While my main responsibility lies in working with alfalfa and forages I also was pleased to find out that there were several folks in Wisconsin that were using cover crops!  Well, you would figure that I’d get involved more with cover crops in the Badger state, and I have.

Wisconsin Cover Crop Meetings

In February 2012 I conducted two cover crops meetings in the Fox Lake, WI area with over 75 producers present. The purpose of these meetings were to teach farmers about how cover crops can work in their farming operations.  I was very pleased with the outcome of those meetings as over 10,000 acres were planted on farms that were represented at those meetings.

In July I held three more cover crop meetings in Eau Claire, Waupaca, and Brillion, WI. All combined, there were over 150 farmers present and I’m confident that there were at least 30,000 acres of cover crops planted by those farmers.

While I don’t have figures of how many cover crops were planted in Wisconsin, I think there were as many as 250,000. Many of those acres were after wheat was harvested and a surprising number after corn and soybeans.

Cover Crops for Forage & Manure Management

Feed was one reason so many acres were planted. The severe drought has created a forage shortage.

But many farmers planted their cover crops because they want healthier soils and better production.  Still others planted because they want to hold onto the nutrients from their manure.  Whatever the reason, cover cropping is alive and well in Wisconsin – and growing.

You can click on the pictures below to see a larger image of each.

The Oats, Appin Turnip and Cowpea combination should make excellent haylage for the Wisconsin dairy market.
The nodules on the Austrian Winter Peas were multiple and large. This field will be planted to corn next year and it sure appears that a good amount of nitrogen will be in the soil and available for that corn crop.
This field of Austrian Winter Peas and Radish east of Green Bay, WI was planted after wheat in severe drought conditions. Thankfully some later rains came to get the mixture up and going.

Cover Crops in the Great Plains – a view from a long time cover crop user- Part 1

I’ve had the privilege of meeting a gentleman from Kansas named Paul Conway.  Paul is an avid “cover cropper” and he has been for nearly 20 years! Paul reminds me of my father, who was an early pioneer of no-till (over 40 years of no-tilling on our farms).  I have asked Paul to give a more western feel to this blog since he has a different perspective on some of the cover crops that work well in the Great Plains that I typically don’t share.  I will be using Paul’s writings with his full permission.

In this post I will share Paul’s perspective on how and where cover crops fit in different systems.  Again, these are Paul’s views from his perspective, of which I find myself agreeing with.

Vegetables:  Using cover crops is vital for long term sustainable vegetable production.  Vegetables are fertility hogs. Intensive vegetable production will ruin soils no matter how much fertilizer you use. Fortunately the quick maturity and low residue of most vegetables allows many opportunities for the use of cover crops, more so than with field crops.

This is good and bad news. The variety of choices can overwhelm growers who want simple answers.  Use manure whenever possible in vegetable production to build organic matter especially when used with the cover crop grasses such as sorghum-sudan, grain rye, annual ryegrass, etc.

There are many opportunities for cover crops in both conventional and organic cropping, actually more so than in field crops.

Traditional field crop systems:  By this I mean the 1940-50’s ideal of animal husbandry and cash crops on the same farm supported by a varied rotation of row crops, small grains, and forage legumes (either alone or with grasses).  Cover crops are useful but not vital, as the rotation and manure application keeps the production system going.  Cover crops allow modifications to the rotation. Also annual warm and cold season grazed cover crops saves money and further diversifies the rotation.

Modern monoculture field crop systems: Corn and soybeans aren’t much of a rotation since they are both row crop summer annuals.  Cover crops are vital to long term sustainable field crop production since they essentially mimic the effects of a decent rotation as well as provide the agronomic benefits that you are well aware of.  Cover crops are easier to use if small grains are added to the rotation.

Grazing: Grazing warm season as well as cool season cover crops is a direct financial benefit of cover crops, as opposed to the recognized indirect financial benefits and adds diversity to the rotation.

 

A Note from Paul Conway about who he is and about his experiences:

I grew up mostly overseas and I have gardened all my life.  When I was a teenager I worked on farms in the summer.  I retired from the US Army in 1993 and started my market garden to grow vegetables commercially.  I have done this ever since except for 17 months in 2006-7 when I was recalled to active duty and sent to Iraq.

I have farmed organically since 1993. I was organically certified from 1994 until 2004 when I switched to Certified Naturally Grown, a certifier more friendly to small scale local market vegetable growers.  

I should say that organic farming does not work unless you pay almost fanatic attention to building and maintaining healthy soil. This means good crop rotations with a mix of row crops, small grains, and forages.  You must use manure (if available) and cover crops/green manures.  The degree of mix between the two is complex and farm dependent.  Simply switching to organically approved inputs without a good soil building rotation will not produce good yields.

Also, thanks to Paul for serving the USA in the armed services!

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.