Plant Cover Crops

Learning about the benefits of planting cover crops.

Turnips

Cover Crop Turnips – A Good Choice Over Radishes?

Cover Crop Radishes or Turnips as a Cover Crop – or Both?

Cover crop radishes certainly receive a lot of press. I have researched them quite a bit over the past four years. On this blog alone I have over 20 posts about radishes. They are fun to take photos of, dig around in, research, and even play baseball with.

It is hard to pick up a publication that mentions cover crops and not read about radishes and their benefits.  Some industry and university cover crop research leaders like Steve Groff and Dr. Ray Wiel (University of Maryland) have researched radishes for over 10 years.You might say that cover crop radishes are the “Rock Star” of cover crop species these days.

What About Turnips?

The Oats are nearly 30" tall and the turnips are around 18" in this Oactober photo. The Cereal Rye was about 6" tall at this time. This mixture was planted in late August and the photo was taken Oct 22 - approximately 8 weeks after planting. My daughter Grace was the model..
The Oats are nearly 30″ tall and the turnips are around 18″ in this Oactober photo. The Cereal Rye was about 6″ tall at this time. This mixture was planted in late August and the photo was taken Oct 22 – approximately 8 weeks after planting. My daughter Grace was the model..

Why are turnips used as a cover crop so little compared to radishes? Are they the “ugly step-sister” of the Brassica family?

Let’s look at some of the benefits of turnips. Some newer varieties (Appin in particular) provide a bulb that is almost entirely in the soil and a deep root system (though a smaller bulb/tuber than the radish).

Benefits of Turnips

  • Turnips are very palatable for grazing cattle and sheep.
  • Most turnips survive the winter and hold onto nutrients into the spring (longer than radishes).
  • Turnips sequester nutrients in a similar fashion and amount as radishes (see data below).
  • Turnips are easy to kill in the spring.
  • Turnips do not have the odor problems that radishes have (therefore they can be planted more “safely” in areas closer to towns or neighbors).

“Problems” with Turnips

  • Not all turnips are created equal. The old purple top (or that type) turnip and even the tankard type turnips have very little of the bulb in the soil – thus less soil activity.
  • Most turnips survive the winter and then need to be killed in the spring. Yes this can also be a benefit.
  • The turnips “bolt” in the spring and want to produce seed. Kill them as early as possible.

    Turnips will overwinter in the spring. The turnips above flowered out in March 2012 in central Indiana. This is nearly 5 weeks before “normal”

Frequently Asked Questions

  1. If we mix turnips and radishes together, is that okay?  YES – for grazing or for just using as a cover crop.
  2. If we plant turnips instead of radishes is that okay?  Yes – just be aware of the differences and that the turnips will most likely survive the winter.
  3. What if we are just looking to graze and only care some about the cover crop?  Choose turnips.
These three brassica types were collected from a Loundonville, OH farm in the fall. Pasja Hybrid Brassica (L); GroundHog Cover Crop Radish (C); and Appin Turnip (R). Note the difference in tops versus tubers.

 

Nitrogen tested in Radishes/acre from Loudonville, OH dairy farm  averages 200 units of N (data collected November 2010)

Nitrogen tested in Appin Turnip/acre from Loudonville, OH dairy farm showed nearly 300 units of N (data collected November 2010)

The turnip tops had nearly 200 units of N/acre.  This was NOT scientific but it is instructive that turnips are an excellent scavenger of N.

Grazing Cover Crops

These cattle have a great body score as they graze on December 6, 2011 in northern Indiana.

In early December, 2011 I visited two farms in Kosciusko County Indiana (NE IN) where producers had intentionally planted cover crops after their wheat was harvested for the purpose of grazing cattle and improving soil.  One of the producers planted a mixture that was featured in this blog.  His Oats/Cereal Rye/Turnip mixture looked beautiful and it appears he will have more feed than he needs to get the cattle through December without feeding much hay!  Only a severe ice storm or exceptionally wet soil would seem to prevent that from happening.  Here is a video my wife and I took from this field.

Just down the road a different farmer planted a different mixture.  His pastures were decimated by the summer drought and over grazing.  Frankly I would not have recommended the mixture he planted…only because I was not sure how the cattle would graze cover crop radishes.  His mixture was 3# Appin turnips and 3# of GroundHog cover crop radishes.  That was all…When my new farmer friend drove me by the field I did not see the cattle…and even then I was noticing a lot of bare soil (the area between all of the brassicas) and was longing to see oats or some grass species out in the field with the brassicas.  Then we found the gent that planted the field.  He was ecstatic!  The cattle were grazing both the turnips and radishes very well. His cattle had great body condition and his feed bill was way down.  My only recommendation was that he feed dry hay to the cattle along with the brassicas so that they would not end up with some health issues (acidosis, foundering, etc…).  Brassicas should not make up more than 30-35% of the diet for cattle and he was at over 80%.  Watch a video from this field.

Here is my wife in the field of cover crop radishes and Appin Turnips on Dec 6, 2011. Note the uncovered soil...that is just another reason to add oats and or cereal rye or annual ryegrass to this mixture.

 

The cattle needed more fiber in their diet so they ate a significant amount of turnip bulbs. They ate far fewer radish tubers than turnip tubers.

 It is very important to include fiber in the diet of the cattle when grazing turnips and radishes.  The forage quality of the brassica is too high for the cattle to have a healthy rumen. If the producer that planted only the brassicas had fed straw or lower quality dry grass hay the cattle would have been healthier.  I believe that is why the cattle were eating so many bulbs…they needed more fiber.

This line of straw bales were used for bedding in the barns instead of feed for the cattle in the brassica field.

 

Cover crops for gardens – and my wife, the cover cropping queen!

My wife Sally must love me…or at least she is observant to see how cover crops are improving the soil in our family gardens.  Over the nearly 19 years we have lived in our home we have had a garden where we often have raised vegetables for the Hispanic families that we minister to.  A few years ago we had nearly 50 chili plants of various types (Jalapeno, Serrano, Habanero, etc…) and we raised several bountiful crops.  But we found that after raising these crops that we had few if any earthworms and our soil was becoming more compacted year after year.  We decided to put the gardening on hold in some plots as we look to improve our soil.  Just as last year, Sally planted different cover crops in August into some garden plots.  I need to explain, these plots are in the front of our house…right near the road!  My wife is a pretty bold cover crop user (and a good advertiser as well).

This Austrian Winter pea and cover crop radish mix fill one garden patch.

Why would she plant cover crops in our gardens?  The main reasons are to enhance the soil quality with earthworms and to reduce soil compaction.    Sally is a pretty “eco-friendly” gal as she recycles everything and she knows the value of taking care of the soil.  What we have found in the past 12 months is an increase in our earthworm population and several more roots in the soil to help build organic matter.  I expect that we will have some veggies in these garden plots next year.  I’m confident that Sally is doing the right thing by improving our soils…even if it is only a few square feet at a time!

 

A mixture of turnips, cover crop radish, and crimson clover is helping build the soil in my wife's garden plots.
The front of the Robison "Agronomy farm" house in Winona Lake, IN. Note that Sally let's me have a "Cliveden pasture green" house too! It must be love!

 

Grazing Cover Crops in the Winter

Over the past 9 years I have worked with Ed Ballard from the University of Illinois on grazing cattle over the winter.

During the first 4-5 years I was much more concerned about the “above ground” aspect of the cover crop and weight gain by the animals.

However, these past 4-5 years have shown me the dual benefit of this amazing plan.  The mix I use is 1-1/2 to 2 bushel per acre of oats, 1 bushel of winter rye and 5# of Appin Turnips.

This mix works well flown into standing corn or drilled right after the corn harvest.  I have attached a You Tube video to show the wonderful benefits cattle producers can get using this cover crop.