Plant Cover Crops

Learning about the benefits of planting cover crops.

Breaking Up Compaction

Fall Cover Crop Management

While in southern Minnesota in early September 2013 I was asked when a farmer should plow his cover crop field this fall because he needs the fields to be “black” this winter in preparation for next spring.  I shuddered.  There I was in a beautiful field of cover crops that are jump-starting some biology on a “biologically dead” field and the farmer wants to kill his biology driving mechanism.  UG!  The main reason he wanted to till the field was to have warmer soils in the spring where he had black soil.  I shared that our research sowed much different results.  His thought process sound right but has proven to be a myth, not a fact.

A beautiful stand of Oats, Berseem Clover, and Pasja Hybrid Brassica on prevent plant acres in SO. MN
A beautiful stand of Oats, Berseem Clover, and Pasja Hybrid Brassica on prevent plant acres in SO. MN

I told the farmer to leave the cover crops in all winter and use conservation tillage next spring.  (He’s not a no-tiller.)  We dug some shallow root pits for a field day and we found many problems that I believe can be somewhat rectified if the cover crops are left in all winter.

We found many soil health problems in this prevent plant field

  • Severe compaction– many areas had compaction starting at 2-3″ deep.  Part of that was from spring tillage of wet soils…but the compaction was about 8″ thick as the soil was coming up in blocks the size of cinder blocks!
  • Lack of soil biology – I know this because we found a significant amount of corn fodder 2 foot deep that was not even breaking down.  It would have been buried with the deep ripper 18 months ago.  I could not believe my eyes!
  • Lack of aeration in the soil – the soil was literally rock hard.  We did find a few earthworm channels but it was so dry that worms were small and deep.
  • Low organic matter – I’m not sure how low it was but there was very little soil structure.  I talked with a regional NRCS employee and the local SWCD specialist and both men lamented that many of the soils in that region were “about as bad as this one”.
We found corn fodder two feet deep that had not yet decompose after over 18 months.
We found corn fodder two feet deep that had not yet decompose after over 18 months.

I need to be fair.  The farmer currently renting this field has only farmed it a few years and he is making major strides to improve this farm.  But he has lots to accomplish before he has a healthy field.  Having cover crops are a great first step and he knows it.

Other solutions (instead of cover crops) being proposed to fix the “tight” soils (“unhealthy” soils) in the region

  • Tile – LOTS and LOTS of tile has been installed in prevent plant acres this year.  Farmers know they need aeration and percolation in their “tight” soils.  The regional specialist from NRCS lamented that many farmers don’t believe that cover crops are a solution to make their soils better long term.  Tile is not bad; but tile and cover crops are a much better solution.
  • Deep ripping – this will get air into the soil and break up compaction, but will it build soil health?  No, it will not  (note the corn fodder found 2 foot deep in a root pit).  Let cover crops naturally deep rip the soil.
  • Tillage- and lots of it – many fields in the area had been tilled (disked, field cultivated, etc…) four times already to control weeds…Unfortunately it also reduces organic matter and soil structure and soil health.

So what should happen with the cover crops heading into winter?

  • Leave the cover crop growing into the winter – This will give the best opportunity to help with aeration and percolation.  This also helps build soil structure and reduce compaction.  (See deep ripping, and tiling above…just let the cover crops do this naturally!)
  • Sarah Carlson from Practical Farmers of Iowa recently wrote an article about this topic and you can find it here Prevent Plant, Cover Crops, Now What 2013.
  • Let the cover crops keep putting down deep roots – we found roots of crimson clover, radishes, cereal rye, annual ryegrass, oats, and Pasja all around 24″ deep.  Let them keep growing deeper to open up the soil to get air and moisture deeply into the soil profile.
This 5 week old PileDriver Radish shows the compaction zone starts at around 2-3" seep. Roots on this radish went over 24" deep despite very dry conditions.
This 5 week old PileDriver Radish shows the compaction zone starts at around 2-3″ seep. Roots on this radish went over 24″ deep despite very dry conditions.
This field had very poor soil structure. The regional NRCS specialist told me that many fields in the area had similar issues
This field had very poor soil structure. The regional NRCS specialist told me that many fields in the area had similar issues

Root Pit Reveals 40″ Cereal Rye Roots

Rye Pit

I am blessed to hear from farmers around the world about their cover cropping adventures.  One young man, Brian Scott, from Carroll County, Indiana has generously shared his information with me again this spring.  This post is Brian’s report from early May, 2013.  To see Brian’s photographs, click here.

We dug a few pits in our field today that has about 40 acres of cereal rye and another 40 of annual ryegrass. The cereal rye had a pretty good stand, but the ryegrass didn’t do so well over the winter.  Looks like we may not be the only farm with that problem this year?

Anyway I was pretty excited for our first year cover cropping that we found cereal rye roots down to 40″ today!  And we hit the water table below that since everything is still relatively wet from all the rain.  I wouldn’t be surprised to see more roots if we could have dug down deeper.  That was on pretty good soil that used to have manure applied every year until about 7 years ago when we got out of the hog business.

The ryegrass was on ground with much more clay near the surface, but I was glad to see we had roots down 2 feet where we did get a decent stand.

Both covers were sprayed today.  I think I would have liked to keep the cereal rye a bit longer, but with rain in the forecast we didn’t want it getting out of control if we got soaked again and couldn’t spray.  These were all seeded into standing corn on 9/19/2012.  In all we had about 200 acres of cover this year and have plans to seed at least 400 in the fall!

Thanks Brian!  And to everyone who have been sending info…watch for it to be on the blog soon.  Thanks to all who are sharing their stories.

Followup in On-Farm Cover Crop Trial

The corn is now harvested at Robison Farms in rural Greenwood, IN and we are pleasantly surprised.

Accurate Yield Estimates

We actually achieved a somewhat higher yield than the hand check “guesstimate” that my brother Don and I made back in August.  We reported this yield in the blog post Cover Crops Provide Improved Corn Yields in On-Farm Trial .  The actual yield was 107 bushels per acre across the whole field and our estimate was in the  105+ bushels range.

This gives me confidence that the differentiation we showed in the yield in the different cover crops and cover crop mixes was pretty accurate.  As you will see on the blog post there were some mixes that yielded more than 50 bushels per acre better than the no-cover crop check.

Impressive Root Structure and Soil Moisture

Would the whole field have averaged 50 bushels per acre better if it had all been in cover crops in 2012? I doubt it.

But I think it would probably have been quite a bit better than what the field averaged without cover crops. Here’s why:

  • Better Root Growth
  • Greater Amount of Soil Moisture

One reason that I think there would have been a significant yield increase over the whole field is because of what Don and I found when we dug up some plants. We found more moisture and more roots where we had cover crops versus where we had no cover crops.

In the non-cover crop area:

  • We had to use a shovel and a pick-ax to dig.
  • The ground was exceptionally compacted, hard, and dry.

In the cover crop area:

  • We used just a shovel to dig.
  • We had much less compaction (in most areas).
  • It was distinctly more moist (like comparing a fairly dry sponge versus a sponge that had not been submerged in water for 2 months).
This corn plant was dug up in the area where we had a cover crop mix in mid-August 2012 under severe drought conditions.  Note the additional root and the moistness of the soil compared to the photo to the right.

 

This corn plant was dug from the non-cover crop check area with a pick-ax and shovel. The ground was compacted, hard, and very dry. It is amazing that the corn looked as good as it did!

 

 

 

 

 

 

 

 

 

 

Don Robison holding up a corn plant from the cover crop plot area that had Austrian Winter Peas and Radishes.  Look at the root-ball and moisture compared to the next photo.

Don is not working near as hard to hold this corn plant from the non-cover crop check area. The root ball was smaller and the soil was much drier. I’m not sure why Don was smiling. Most of the 50 acre field did not have cover crops! Like Dad would sometimes say, “get that smile off your face!”

Earthworms

As Don and I were digging in the areas where we had cover crops we were pleased to find earthworms. There were no earthworms to be found in the non-cover crop check area.

This field has been no-tilled for most of the last 20 years and we usually find earthworms, but it was so hot and dry that I assume the worms either died (fried) or went deep into cooler, more moist soil (this year that may have been 5-6 feet deep).  But again, we found some earthworms in the cover crop plot area.

In retrospect, we should have compared soil temperatures on the day we dug roots and took yield estimates.

An earthworm in the cover crop plot area. Though we did not see many in the plot area we saw none in the non-cover crop check area.

 

As dry as the summer of 2012 was, it was interesting to find earthworm activity in the area where we had the cover crop plots. There was no such activity evident in the non-cover crop check area.

 

 

 

 

 

 

 

 

 

 

 

The Takeaway Message from Robison Farms in 2012

  • Cover crops can increase corn yield even in very dry years.
  • Corn following cover crops consistently out yielded corn that was not following a cover crop in hand check yield estimates.
  • Hand check yield estimates were consistent to actual yield on the non-cover crop check.
  • Cover crops can help preserve soil moisture even in a severe drought.
  • Corn roots following cover crops appeared to be consistently larger and deeper than where there had not been a cover crop.
  • There was more earthworm activity in the cover crop areas.
  • There was less compaction in most cover crop plots compared to the non-cover crop check.

In a future post we will look at “Crop Health Imaging” maps that Beck’s Hybrids did for our farm.  These were taken a bit late in the season but they were still very interesting…and telling!

 

 

 

 

 

Cover Crops Planted After Wheat in a Dry Year

Can you still gain value in a cover crop when it is planted after wheat in a dry year?

During the week of October 15, 2012 I traveled a wide swath of Wisconsin looking at cover crops.  In the eastern half of the state the cover crops looked very good.  In the western half the cover crops looked desperately poor.   The difference?  Moisture.

Northwestern Wisconsin – Terribly Dry

While on farms near Osceola, WI (right along the St. Croix River – the river that forms the border between Wisconsin and Minnesota in that part of the state), I observed a sad sight.  Cover crops that had been in the ground for 6 weeks were either not germinated  or had little growth.  While the early part of the growing season had more than adequate rainfall and corn yields were near 200 bu/acre, the last 7-8 weeks has seen less than 1/2″ and the cover crops look…well, they look horrible.

Central Sands Region – Dry But with Some Promise

Near Hancock, in the Central Sands Region of Wisconsin, there is a mixed bag of results.

Where farmers used irrigation to “water -up” the cover crops, there are nice stands with adequate growth to have a “successful” cover crop to achieve many benefits.  Unfortunately, where there was no irrigation used there was much less “success.”

Again, it was dry for several weeks before and after the cover crops were planted after the wheat crop had been harvested.  A few days before my cover crop field day there was a 4 inch rain.  The farmer and dealer present said that the plot “changed overnight” as it had grown so much since there was some moisture.

The beautiful thing about the cover crops in the central sands is that they established and actually looked amazingly good compared to what I envisioned they would. The winter cereal rye was tillered nicely and the oats were 5-6 inches tall.  The radishes, oats,and rye all drilled through the compaction zone that we found at 3-4 inches deep.

What was not apparently impressive was the crimson clover or Austrian winter peas – at least not for coverage or height. The crimson clover was only about 1 inch tall and the peas were 3-4 inches tall.  However, what was surprising was how many nodules were on the clover and peas and that the roots were 4-5″ deep and through the compaction zone as well!

Northeastern Wisconsin – What a Difference Moisture Makes

The crimson clover was not at all impressive even though the seed was planted 7 weeks previous to this photo being taken. However, with virtually no rainfall it is amazing there was any clover established at all in the Central Sands Region of WI.
Seven or eight weeks of dry weather did not help cover crops in this field near Osceola, WI emerge very quickly in 2012. Will there be any value to this cover crop? Sadly, no.  Note how small the radishes and turnips are.  These cannot be declared valuable to this farmer.  Thankfully the winter Rye should survive the winter.

 

 

 

With less than 1/2″ of rain since planting into dry soil, this cover crop field in western Wisconsin near Osceola never had a chance to achieve the goals the farmer had for it improving the soil.

 

 

 

 

 

 

 

 

 

This is the test plot in the Central Sands Region.  From Right to left; Radishes, Oats, Winter Rye, and various mixes. Are these cover crops valuable? I believe so because they are through the compaction zone and the rye and many of the mixes will have components that survive the winter.

 

 

If you enlarge this photo you will be amazed how many nodules are on this tiny crimson clover plant. The roots were over 5″ deep which was through the compaction zone at the Hancock, WI plot.

 

 

 

 

 

 

 

 

 

Cover Crops and Bears?

Radishes, Crimson Clover, and Bears

Walking in cover crop fields in northern Indiana is easy compared to doing it northern Wisconsin.

In northern Indiana my main issue is tripping over large radish tubers sticking out of the ground.

In northern Wisconsin my main issue was that plus watching out for bears. I’m not talking about the Chicago Bears…but real live black bears!  Although I did not see any while conducting cover crop field days near Coleman, WI on October 18, 2012, hearing the stories about the bears raising havoc while AgVentures Co-op employees were harvesting corn plots made me quite nervous.

The cover crop plot was fabulous. There were 5 different mixes to observe plus straight radishes planted at 8#/acre.  The cooperator plans on taking yield tests over each different cover crop mix in his 2013 corn crop.  If he is able to do that I’ll keep you informed of the results.

This cover crop plot near Coleman, WI had beautiful radishes with large tubers – and thankfully NO bears!

 

 

 

 

 

 

 

 

 

 

 

 

The radishes were from 1″ to 3″ in diameter and quite deeply rooted. There was manure applied after wheat harvest so the radishes were “well fed”.