Legume Inoculant

zeedman Zone 5 WisconsinSeptember 8, 2006

A question that has often arisen in both the Bean and Vegetable Forums has been: "Does the use of bacterial inoculant on beans, peas, and other legumes provide noticeable improvement?"

To this end, has anyone performed a side-by-side comparison? Or know of a study that was done on garden legumes (beans, peas, limas, cowpeas, peanuts, etc.) independent of the inoculant manufacturers?

I have always used the proper inoculant on all my legumes each year... and that is the problem; the bacteria are already present in my soil from previous applications. Any trial by me would only demonstrate the relative advantage of annual application of inoculant, vice plants grown with the residual population alone.

To perform a proper experiment on the relative advantages of inoculant application during planting, both the treated & control would need to be grown on new ground (or where legumes have not been grown previously).

Anyone interested?

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dchall_san_antonio(8 San Antonio)

I think the experience among growers down here is that the inoculants work much better in organic gardens and still better in no-till organic gardens.

    Bookmark   November 9, 2006 at 12:04PM
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I have a new area that I have turned over recently. It was part of my lawn, nothing but grass has ever been there. I have on hand 1/4lb. Bluelake Bush and 1/4 pound Strike(r) Bush.
I have put compost,alfalfa slush,and dry molasses over the area.
I want to see for myself if I wasted my money on the innoculant...If I did zeedman..will you send me some diff. seeds? hahaha probably not allowed to bet here huh?lol

    Bookmark   January 3, 2007 at 8:58PM
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albert_135(Sunset 2 or 3)

...can be found at the link below.

Here is a link that might be useful: Plant Physiology Online Chapter 12

    Bookmark   January 19, 2007 at 5:18PM
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zeedman Zone 5 Wisconsin

This forum has been really slow over the winter, so I just got around to checking Albert's link. I found no "serious discussions", just a brief summary of a chapter of a course. Nothing that either supports or refutes the effectiveness of inoculants for leguminous crops.

Now that planting time is approaching for most of the U.S., I am hoping that more GW members will take a greater interest in this experiment.

    Bookmark   March 23, 2007 at 4:12PM
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I may be able to take part in this experiment. I'm planning on planting 3 15' rows of blackeye peas and the same amount of blue lake bush beans. It would be quite easy for me to inoculate only 1 or 2 out of the 3 rows. Blackeye peas grew well in this area last year without fertilization or inoculation, but I did not check for root nodules. Hopefully I can at least give some anecdotal evidence as to the effectiveness of inoculating--might even go so far as to weigh the harvest if there is an obvious difference in yield. My concern right now is finding the proper inoculant for blackeye peas (cowpeas). Most garden centers carry only the "garden combo" inoculant, and it may not be listed for cowpeas.


    Bookmark   April 5, 2007 at 5:22AM
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It looks like this post got lost and no one really attempted this experiment.

I would like to give it a try next season. I plan on growing Pole beans next year for the first time in ground that has never been under vegetable cultivation(my backyard yard). I will make a note for my next year planting to try out this experiment.

I assume I can get "Legume Inoculant" at my local garden supply centers? Any application advice?



    Bookmark   October 2, 2007 at 11:30AM
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prairiemoon2 z6 MA

Wondering if anyone ever tried this experiment?


    Bookmark   September 4, 2008 at 12:13PM
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I bought inoculant. However, since I've neglected housecleaning in favor of balcony gardening, I can't find the inoculant now. I then figured that I'd wait until spring to plant my sugar snap peas.

I asked the master gardeners at the farmers market, and they said that most commercial seeds come pre-inoculated. Said something about there is a visible pick or white dusty coating.

    Bookmark   September 21, 2008 at 1:54PM
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Beeone(4 N. Wyo.)

If inoculated seed has ever been planted in the ground and legumes (preferably the same species, such as beans) are grown every few years, the soil will maintain a reservoir of inoculant and additional treatments won't make much if any difference. The way to tell if you need to add inoculant is to pull a plant in mid summer and see if the roots have pinkish nodules on them. If they do, you are fine. If they don't, then adding inoculant will help.

Still, it never hurts to experiment. Just remember, the inoculant is a living bacteria, so store it in a cool place, and it is best to use any inoculant purchased in the year you get it.

1 Like    Bookmark   October 25, 2008 at 2:48AM
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Has anyone tried making their own inoculant by low temp drying of nodules and soil surrounding them to avoid having to buy inoculant every year

    Bookmark   January 7, 2009 at 12:48PM
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jmsimpson9(CA 8/9)

I will be testing this year. Several years ago I started a new garden. Beans have only done so/so each year. This year I am trying the inoculant.

    Bookmark   March 10, 2009 at 6:21PM
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dirtdiggin(8b NW WA)

Hello, I saw this post and thought I would offer my results at the end of the season.

It was quite interesting...luckily I had ordered a pack of inoculant online, but wanted to pick up another due to the qty of legumes I'll be planting. Have you ever been looked at as though you were from outer space? Exactly my experience when I asked the gentleman from Home Depot, where their seed inoculant was. "Our what?" he exclaimed, "What's it for?" So I proceeded to explain. He looked at me like I was nuts and said, "It sounds like a real sophisticated product and you'll probably have to go to a real nursery to get it."

I was a bit surprised...but hey, what do you want from HD?

Anyway, I am currently having to plant in containers, so I figured I'd test out half of the legumes (both peas and beans and about 40 varieties) and see the difference in growth and production. Obviously, there is no residual inoculant from previous years, in the buckets. All new soil etc. So, when I get to harvest time, or if I notice any difference between the plants during the growing season, I'll post my results. It will be fun to see which do better or if there will be a difference.


    Bookmark   May 8, 2010 at 9:24AM
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I'm wondering if you did the experiment? Love to know the results!

    Bookmark   November 23, 2010 at 6:01PM
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Called the extension offices around here and got the area's horticulture specialist. He said that it is a good idea for newly dug gardens, and will definitely improve the yields if the nitrogen-fixing bacteria are not present already. If you have planted beans, peas, clover, alfalfa, buckwheat or legumes at any point in the past, within about 10-20 feet, or more if you've tilled, it should already be there, and won't be necessary.

    Bookmark   February 28, 2011 at 4:19PM
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Where would you GET lugume inocculant, particularly for obscure legumes like Beach Pea and false indigo?

    Bookmark   May 22, 2013 at 10:56AM
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zeedman Zone 5 Wisconsin

Wow... this forum is so inactive I had forgotten this post. I never did get any volunteers for a true "with vs. without" comparison for any legume. And I never came back to post my own results.

I did inoculated vs. inoculated comparisons for common beans, runner beans, garbanzos, mung beans, soybeans, and cowpeas. The object was to grow all rows for dry seed, and weight the seed at season's end for comparison. As I stated, I had used inoculant previously in that garden, except for garbanzos.

The mung beans were wiped out by disease, so no data. The garbanzos bore seed, but the seed was destroyed by late summer rains... a pity, since that was the only inoculant that I had used for the first time. Common beans & runner beans had no observable differences.

The soybeans that were inoculated were half eaten by herbivores (it turned out to be a ground hog), but the remaining half, when compared to an equal ratio of the uninoculated row, showed little difference. Any soybean in my garden, inoculated or not, was heavily nodulated. That bacteria seems to be especially persistent in my climate.

The only real difference was noted in cowpeas, and part of that was due to factors not planned as part of the experiment. The inoculated row of cowpeas was much greener, the pods were noticeably longer, and the dry yield was higher. Furthermore, the two rows were at right angles, and met at the corner... the first two plants in the uninoculated row, closest to the inoculated plants, were much greener than the rest of the row. The opposite end of the uninoculated row was unremarkable, so the edge effect could not account for the healthier plants. I concluded that enough inoculant had been spread in the surrounding soil to influence uninoculated plants within a 4-foot radius.

The other incidental observation came from yardlong beans. I normally start them as transplants, inoculated at the time of planting. Because I was controlling inoculant application for the experiment, I accidentally failed to inoculate them. There were three varieties, and all of them languished - the worst crop I have ever had. Inoculated the next year & subsequent, that poor growth has never been repeated.

It is my conclusion that the bacteria for cowpeas & yardlongs does not persist in my soil; perhaps that strain is unable to survive my Wisconsin winters. Based upon my observations, I recommend annual application of inoculant for cowpeas, in northern climates.

    Bookmark   March 3, 2014 at 10:16PM
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edlincoln, guessing you would find the closest common relative of whatever legume for which you're searching and use that inoculant. Like I said, though, just a guess.

Zeedman, thanks for the info regarding your results. Interesting, and probably useful here in MN.

    Bookmark   March 21, 2014 at 7:50PM
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i wanted to buy a small amount and propagate it, but i had read that they need to be in the presence of roots to be active and reproduce.
thats why you can buy a sealed container and it lasts for months or years.

so, my idea was to get some roots and put them in a blender.
Then add molasses,, water and aerate...

would this work to make them reproduce ?

if so, we could each make a batch and trade here online.
especially for anyone making it from local soil

    Bookmark   June 10, 2014 at 1:24PM
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