Why Soybeans Look Great After Cereal Rye

Barry Fisher, Indiana State Agronomist for NRCS in the pit in the grassy area that had shallow roots.

In Mid-August I had the honor of speaking at a cover crop field day in Tipton County, Indiana.  At that field day there were some root pits dug that were quite interesting.  One of the pits was in an area where some top soil had been removed and fill dirt had been put back over the top of where soil had been removed.  Now that area is a “grassy pasture-like” area.  What surprised me was that the roots on the forage grasses were not particularly deep into the soil profile – only 10-15″.  I found them to be much more shallow rooted than expected.

In the other pit the producer had been no-till farming for a number of years and for the past six years using cover crops as well.  In this pit we found soybean roots much deeper than forage grass roots!  See the video here. The cover crop used last year in the field was winter cereal rye.  The soybean crop looked excellent in a very dry time of the year.

Observations from the pit in the soybean field:

  • soybean roots around 40 inches deep
  • large nodules approximately 20 inches deep
  • dense, thick, healthy soybean roots

Markers along the side wall of the soil pit show evidence of soybean roots found at different depths.

Large soybean nodules found around 20 inches deep following a cereal rye cover crop in a continuous no-tilled field.

Obviously we don’t know the yield on the soybeans yet but they sure podded up well and I’m confident went through the drought better than shallower rooted soybeans.

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5 Responses to Why Soybeans Look Great After Cereal Rye

  1. Art Behrens September 9, 2011 at 10:02 am #

    I plant a rye cover crop before beans. I plant the rye cover crop about mid November and disc it under when it is about 5-6 inches tall about first of May. I imagine the rye roots do not have enough time to get down as deep as you were talking about in the article. How long does the rye have to grow to be the most effective. If I plant the rye in mid September would I get this benefit or do you have to let the rye grow and reach mature growth. Thanks for any input you may have.

    Thanks
    Art Behrens
    Carroll Iowa 51401

  2. Dave September 9, 2011 at 9:55 pm #

    Art,

    Much of the rye growth is done by early spring. However, this past year we were so wet that much of the rye went to head. I do believe that we did get deeper roots as a result of the longer growing time, however, I’m not sure how much more. If you can plant in Mid-September I believe you will probably get deeper roots than if you plant in Mid-November…you will have 45-60 extra days of growth! I’d plant as early as you can for best success.

  3. Paul Ackley September 11, 2011 at 12:32 pm #

    Art,
    We have been using cereal rye behind corn and before soybeans for over 20 years and just in the last 5 become aware of all the benefits and nearly symbiotic relationship of soybeans no-tilled into standing rye either before or after being terminated. Rye is about the only species of field crop that will germinate on top of the soil. This makes it work well to mix with P&K with a little N and spread immediately after corn harvest. Just be sure to be attuned to the weather forecast and spread within a week of 1″ or more of rain.
    Paul

  4. Mark Robison December 21, 2011 at 1:58 pm #

    We’ve used cereal rye for years ahead of soybeans, and have found that earlier planting makes a huge difference in root mass and depth. Our experience has been that rye sowed in november will never have the root mass or depth that sept or oct sowing does, even if left to grow late into the spring. Early sowing is best for root depth.

  5. Dave December 23, 2011 at 11:25 pm #

    Mark, Thanks for sharing that observation! I’ll keep my eyes open for that next spring as plenty of rye was sown in November in NW Ohio and NE Indiana in 2011