Plant Cover Crops

Learning about the benefits of planting cover crops.

cover crop selection

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.

Big Differences in Cover Crop Radishes

This tuber of GroundHog Radish was fairly typical where there was good fertility. This came from a very sandy soil near Melvin, MI. The farmer is very pleased with the results on his 300 acres of radishes.

There are big differences in cover crop radishes.  Some are outstanding and consistent; deep and fairly large tubers (tuber girth seems to be related to fertility and age of stand).  In the thumb of Michigan I saw over 300 acres of fields planted at 10#/acre that were just what the farmer wanted.  We found most of the tubers 8-12” deep and we could not really find the real bottom of the roots as we broke them off in the soil.

These GroundHog Radishes were all within 30” of each other on a blow sand hill. While not all are big, they are all holding nutrients.
 

While some varieties have good tubers, in other instances I have found real problems.  In a field in NE Indiana a SWCD director brought some radishes from a farmer’s field that were verysmall.  The farmer planted around 100 acres of a VNS radish and he was not happy.  I don’t blame him…look at the photo below.

The three radishes to the left are VNS and the radish to the right is the GroundHog variety. The VNS had been in the soil for 3-4 more weeks than the GroundHog radish.

What makes this story even more interesting is that the VNS radish (VNS = Variety Not Stated) cost the farmer 30-40 cents less per pound than the improved variety.  Unfortunately, he’s unhappy because his radishes are not performing.   The farmer saved $3-4/acre and is frustrated.  Two things…and this is for dealers and producers…#1 –Choose to buy from a trustworthy source #2) IF there is a big price savings…beware there is a reason for that spread!  Saving 15-20% on seed is HUGE!  If there is that much saving ask questions and get good answers!

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.