How important is inoculating legume seeds?

[Brookesmith]

For several years I have been inoculating the legumes I plant (summer and winter peas, clovers, vetch, etc) for warm and cool season deer food plots (2-4 acres). It is a little bit of a pain to do so wanted to ask what everyone else is doing. Do you normally go through the extra work to inoculate your legumes?

I normally inoculate the seeds by dampening them with water, applying the peat based inoculant, allow to dry in shade and have in the ground within a few hours (conventional tillage and cover methods -- hoping to do no till methods in future). Sometimes it can be days or weeks before I get any rain (Central Texas). Planting "right before a rain" is not feasible since rain timing is so unpredictable here and I am 3 hours away from property.

Does the inoculant need substantial moisture to survive or can it stay viable for extended periods in dry'ish soil? The inoculant instructions say to keep treated seeds in the shade and plant within 24 hours. So seems like having the seeds laying in dry dirt waiting for rain cant be good.

I did pull up some of my cow pea plants (Iron and clay peas) and sweet blossom clover and did not see any nodules on roots. Maybe I am doing something wrong.

My soil PH is 8.1

Just trying to determine if I have been wasting my time or not inoculating seeds.

 

[S.T.Fanatic]

If you have inoculated in the past and continue to plant the same types of seed there is no longer a need to inoculate.


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[FarmerDan]

Well, I guess it depends on your perspective. Will your seeding fail if you don't inoculate? Probably not. But, well nodulated legumes depend on a sufficient supply of rhizobial bacteria in the soil. That supply doesn't remain constant in the presence of all of nature's affects. Sometimes, I think, when we talk about an aged and fading clover or alfalfa plot one of the factors is lack of elements required for the plant to remain a super manufacturer of nitrogen, elements like rirhizobal bacteria. If you don't innoculate you run the risk of a depleted soil supply. I don't know what the level of risk might be or if it matters to habitat improvement but, given what it can do for a little extra effort and/or cost, you have to consider using it. Don't dismiss it as an unimportant amendment.

https://kingsagriseeds.com/really-inoculate-legume/

 

[SD51555]

I don’t, but I only run clover anymore. I dug a water hole last year and spread 6’ deep solid clay out and made a plot out of it. It looked like hell until mid July, then it caught some traction and just filled out. This stuff could choke out Brock Lesnar.

It only got an 800 lb rate of gypsum and some potash I was getting rid of.

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[SD51555]

At one point back in time, I had found a list of native plants and trees that hosted both species of rhizobia bacteria. I can't find it anymore. I recall though that a few very common trees in the woods host both common forms of rhizobia. I remember tag alder hosting both, as well as either birch or poplar. Well my place is covered in all of that. I figured it just takes a little time for it to find itself and spread.

If you're growing a short season annual, then you probably should buy it, even if you had planted out there before. It only takes a week or two for all the beneficial fungi and bacteria to die if the land has a chem or iron fallow period.

 

[Brookesmith]

Well, I guess it depends on your perspective. Will your seeding fail if you don't inoculate? Probably not. But, well nodulated legumes depend on a sufficient supply of rhizobial bacteria in the soil. That supply doesn't remain constant in the presence of all of nature's affects. Sometimes, I think, when we talk about an aged and fading clover or alfalfa plot one of the factors is lack of elements required for the plant to remain a super manufacturer of nitrogen, elements like rirhizobal bacteria. If you don't innoculate you run the risk of a depleted soil supply. I don't know what the level of risk might be or if it matters to habitat improvement but, given what it can do for a little extra effort and/or cost, you have to consider using it. Don't dismiss it as an unimportant amendment.

https://kingsagriseeds.com/really-inoculate-legume/

Thanks for the article link - good info. Since I have been inoculating for a couple years and I am not seeing nodules forming on my legumes, I am wondering if I am doing something wrong. ?? Is it likely that the bacteria is not surviving when the inoculated seeds are planted in relatively dry soil and waiting for rain? Or could there be another issues preventing nodule formation like soill fertility, high PH (8.1), etc?

 

[FarmerDan]

Thanks for the article link - good info. Since I have been inoculating for a couple years and I am not seeing nodules forming on my legumes, I am wondering if I am doing something wrong. ?? Is it likely that the bacteria is not surviving when the inoculated seeds are planted in relatively dry soil and waiting for rain? Or could there be another issues preventing nodule formation like soill fertility, high PH (8.1), etc?

My first thought was to wonder if you are using the right inoculant. My second thought was to wonder if where you are buying your inoculant is handling it properly. Is it refrigerated? Is it new? There should be some kind of date on the package. Maybe when it was packaged.

 

[yoderjac]

For several years I have been inoculating the legumes I plant (summer and winter peas, clovers, vetch, etc) for warm and cool season deer food plots (2-4 acres). It is a little bit of a pain to do so wanted to ask what everyone else is doing. Do you normally go through the extra work to inoculate your legumes?

I normally inoculate the seeds by dampening them with water, applying the peat based inoculant, allow to dry in shade and have in the ground within a few hours (conventional tillage and cover methods -- hoping to do no till methods in future). Sometimes it can be days or weeks before I get any rain (Central Texas). Planting "right before a rain" is not feasible since rain timing is so unpredictable here and I am 3 hours away from property.

Does the inoculant need substantial moisture to survive or can it stay viable for extended periods in dry'ish soil? The inoculant instructions say to keep treated seeds in the shade and plant within 24 hours. So seems like having the seeds laying in dry dirt waiting for rain cant be good.

I did pull up some of my cow pea plants (Iron and clay peas) and sweet blossom clover and did not see any nodules on roots. Maybe I am doing something wrong.

My soil PH is 8.1

Just trying to determine if I have been wasting my time or not inoculating seeds.

They don't "need" inoculant. If you've planted a legume that uses the same inoculant in that field previously, the likelihood is that there is enough in the soil to do the job. The benefit of the inoculant is that more N will be fixed from the air into the soil. If there is sufficient present in the soil, adding it won't help but it won't hurt. If there is not, it will help. It is pretty cheap stuff. I view it as a cheap insurance policy. If I don't have time to pick it up, I don't sweat it. If I have it handy I use it.

Dan is correct, it inoculant is alive and if it is easy to kill if not handled properly.

Thanks,

Jack

 

[Semisane]

I don't think you have an inoculant problem, but a pH problem. Your reported pH of 8.1 is well above the desired level for clover or peas.

 

[mikmaze]

I skipped it one year when I forgot to add it on to my order, and I saw a difference, won't make that mistake again. Like said, it is cheap. You can easily do an experiment, put a bit out without, the rest out with and watch the results... As also said there are different ones for different crops, the one for sun hemp, might not help your clover, the one for clover might not help your beans, if you rotated away from legumes a year, and go back is it still there? Just use it.

 

[FarmerDan]

I don't think you have an inoculant problem, but a pH problem. Your reported pH of 8.1 is well above the desired level for clover or peas.

Perhaps. no, your are correct so far as yield is concerned. The subject of inoculation and rhizobia bacteria fascinates me. So

Thanks for the article link - good info. Since I have been inoculating for a couple years and I am not seeing nodules forming on my legumes, I am wondering if I am doing something wrong. ?? Is it likely that the bacteria is not surviving when the inoculated seeds are planted in relatively dry soil and waiting for rain? Or could there be another issues preventing nodule formation like soill fertility, high PH (8.1), etc?

This continues to fascinate me. Legumes, nodulation, the use of applied rhizobial inoculation is amazing. So, I dug a little further, but before I share a thought, this inoculate you are buying? Is there anything else that's been added? I learned that some products have included a fungicide...and a few other (less?) helpful things. Personally, I've never seen it.

 

[Brookesmith]

Perhaps. no, your are correct so far as yield is concerned. The subject of inoculation and rhizobia bacteria fascinates me. So


This continues to fascinate me. Legumes, nodulation, the use of applied rhizobial inoculation is amazing. So, I dug a little further, but before I share a thought, this inoculate you are buying? Is there anything else that's been added? I learned that some products have included a fungicide...and a few other (less?) helpful things. Personally, I've never seen it.

I have been using Exceed brand inoculants. See links below. One is specifically made for peas and the other is made for clover. I have kept the inoculant refrigerated until applying to seeds and then allow the coated seeds to dry in the shade for an hour or so before planting. I have no way to know if the feed store where I purchased the inoculant could have mishandled it allowing bacteria to die or how it was shipped. I only add non-chlorinated water to create a slurry with inoculant powder to apply to the seeds.

As I have mentioned previously, after the seeds are covered by dirt it can be anywhere from a couple days to a few weeks before we get adequate rain for seeds to germinate. If the bacteria can die without being kept cool during storage, I question how it can survive in dry soil for days to weeks. ???

Clovers inoculant

https://b6b27d89-c08d-496d-99bb-3bab0636576d.filesusr.com/ugd/8bccab_714e131f5e3a4400a80889bcd310221f.pdf

cow peas inoculant.

https://b6b27d89-c08d-496d-99bb-3bab0636576d.filesusr.com/ugd/8bccab_9053a3e7524648c092bc525cf34fe0a3.pdf

 

[FarmerDan]

I have been using Exceed brand inoculants. See links below. One is specifically made for peas and the other is made for clover. I have kept the inoculant refrigerated until applying to seeds and then allow the coated seeds to dry in the shade for an hour or so before planting. I have no way to know if the feed store where I purchased the inoculant could have mishandled it allowing bacteria to die or how it was shipped. I only add non-chlorinated water to create a slurry with inoculant powder to apply to the seeds.

As I have mentioned previously, after the seeds are covered by dirt it can be anywhere from a couple days to a few weeks before we get adequate rain for seeds to germinate. If the bacteria can die without being kept cool during storage, I question how it can survive in dry soil for days to weeks. ???

Clovers inoculant

https://b6b27d89-c08d-496d-99bb-3bab0636576d.filesusr.com/ugd/8bccab_714e131f5e3a4400a80889bcd310221f.pdf

cow peas inoculant.

https://b6b27d89-c08d-496d-99bb-3bab0636576d.filesusr.com/ugd/8bccab_9053a3e7524648c092bc525cf34fe0a3.pdf

So I found an obscure research paper (it's what I do) on the subject. The experiment, among other things, tested the viability of rhizobia under different levels of soil moisture. Of course, this was in a lab. I think they had 12 different replications - different soil types and different strains of rhizobia. All started at the same moisture level. Then, a third had no water for 15 days and a third no water for 30 days. The number of live strains were counted (?) and, as you would expect the population decreased as the soil moisture dried. But, in each case, some did survive.

Also, there was plant material involved. Again, as you would expect the level of root nodulation followed the same trend.

Not that it matters, effectively, it's not just lack of the little critters, but the plants were suffering the impact of moisture stress. And, it was speculated, to add the proverbial insult-to-injury, the lack of moisture probably blocks the transfer of the bacteria to the plant root. Bang, bang, bang went Maxwell's Silver Hammer. The lack of moisture hits three ways! The plant's stressed, the rhizobia population has decreased and the transportation network to the plant is broken.

 

[Brookesmith]

So I found an obscure research paper (it's what I do) on the subject. The experiment, among other things, tested the viability of rhizobia under different levels of soil moisture. Of course, this was in a lab. I think they had 12 different replications - different soil types and different strains of rhizobia. All started at the same moisture level. Then, a third had no water for 15 days and a third no water for 30 days. The number of live strains were counted (?) and, as you would expect the population decreased as the soil moisture dried. But, in each case, some did survive.

Also, there was plant material involved. Again, as you would expect the level of root nodulation followed the same trend.

Not that it matters, effectively, it's not just lack of the little critters, but the plants were suffering the impact of moisture stress. And, it was speculated, to add the proverbial insult-to-injury, the lack of moisture probably blocks the transfer of the bacteria to the plant root. Bang, bang, bang went Maxwell's Silver Hammer. The lack of moisture hits three ways! The plant's stressed, the rhizobia population has decreased and the transportation network to the plant is broken.

Thanks for sharing that info, very interesting that some bacteria survived for the 30 day period without water.

Am I understanding correctly, this experiment was done with plants that had already germinated? I am wondering what happens if the inoculated seeds lay in relatively dry soil for days to weeks waiting for rain so they can germinate (this is my situation). I wonder if you would get similar results - meaning would we expect some bacteria to survive the dry soil prior to germination and then be able to form nodules once plant germinates (assuming good growing conditions after germination)?

Maybe I am not thinking about that the right way. Maybe once the inoculant is in the dirt, it does not matter if there is a live root along with it or not. And its survival rate of bacteria would be similar to the experimental results you shared. ???

I have been meaning to contact manufacturer of inoculant to ask similar questions but haven't gotten around to it yet. Thanks for your input so far.

 

[FarmerDan]

The bottom line conclusion I draw is you don't stand a chance in dry sandy soil. Oh, maybe seven days - 15 days there's slim hope, and after that not much.

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4468&context=etd

Thanks for sharing that info, very interesting that some bacteria survived for the 30 day period without water.

Am I understanding correctly, this experiment was done with plants that had already germinated? I am wondering what happens if the inoculated seeds lay in relatively dry soil for days to weeks waiting for rain so they can germinate (this is my situation). I wonder if you would get similar results - meaning would we expect some bacteria to survive the dry soil prior to germination and then be able to form nodules once plant germinates (assuming good growing conditions after germination)?

Maybe I am not thinking about that the right way. Maybe once the inoculant is in the dirt, it does not matter if there is a live root along with it or not. And its survival rate of bacteria would be similar to the experimental results you shared. ???

I have been meaning to contact manufacturer of inoculant to ask similar questions but haven't gotten around to it yet. Thanks for your input so far.

 

[S.T.Fanatic]

Not saying you guys are wrong but when it comes to soil, there is always a certain amount of moisture. Even soil that hasn't seen rain in a couple of weeks has moisture. Unless it was roto tilled into powder, that could be another story.

 

[FarmerDan]

Not saying you guys are wrong but when it comes to soil, there is always a certain amount of moisture. Even soil that hasn't seen rain in a couple of weeks has moisture. Unless it was roto tilled into powder, that could be another story.

Yes and no - I guess that's the part of 'not saying you guys are wrong...' - it depends where you look. And that's not the point anyhow. Brooke started with a question about using inoculant because it was a pain in the butt and he wasn't seeing the intended result. He made a lot of good points about the type of soil he was planting into and the lack of precipitation he's experiencing even going so far as to guess more correctly than imagined that the dryness was hindering nodulation because the rhizobium couldn't survive the situation. It sparked my curiosity. There were a number of possible roadblocks. Sandy soil, dryness, high soil pH to name a few. Honestly, my mind went right to the inoculant. From the time it's packaged until its used it has to be handled correctly - like a goldfish. Then, there's the issue of having the right strain. I use it.

In my youngest days I had to write a paper about it to fulfill some academic requirement or another. Then, many years ago, I probably sold a couple tons of the stuff over a number of years. A lot of it ended-up on a truck dashboard. But, I never thought about the things Brooke was questioning. I love a good mystery. It's one of those things that doesn't get a lot of attention because there's no money in it.

Hop, Skip, and Jump.

The inference I took from the research was that low and lower soil moisture levels do the inoculant no good to the point of the odds of success being dismal, more dismal than I would have expected.

You're right. There are no absolutes - except in the lab where they are controlled for good reason. So, to Brooke I say, find another crop that will do better under the conditions you face.

There's another issue and it's the side effect of high soil pH. I didn't read the full research, but, rhizobium apparently are more vigorous when there's an adequate supply of molybdenum. It's deficient in soils with low pH. I understand some inoculants contain a small amount to overcome it, - that, and fungicides which apparently are of no or harmful value. Anyhow, I read that high pH soils tend to be more releasing of the micronutrient normally bound to soil particles in a low pH environment. And, while too little is bad, so too is too much. So, there it is. A bad hand of cards with lots of money on the table.

Yes, there's always moisture in the soil - somewhere, but there are many times when deficient to such a degree there might just as well be none.

See what I can learn by reading Habitat Talk! I love this place....

 

[Brookesmith]

Yes and no - I guess that's the part of 'not saying you guys are wrong...' - it depends where you look. And that's not the point anyhow. Brooke started with a question about using inoculant because it was a pain in the butt and he wasn't seeing the intended result. He made a lot of good points about the type of soil he was planting into and the lack of precipitation he's experiencing even going so far as to guess more correctly than imagined that the dryness was hindering nodulation because the rhizobium couldn't survive the situation. It sparked my curiosity. There were a number of possible roadblocks. Sandy soil, dryness, high soil pH to name a few. Honestly, my mind went right to the inoculant. From the time it's packaged until its used it has to be handled correctly - like a goldfish. Then, there's the issue of having the right strain. I use it.

In my youngest days I had to write a paper about it to fulfill some academic requirement or another. Then, many years ago, I probably sold a couple tons of the stuff over a number of years. A lot of it ended-up on a truck dashboard. But, I never thought about the things Brooke was questioning. I love a good mystery. It's one of those things that doesn't get a lot of attention because there's no money in it.

Hop, Skip, and Jump.

The inference I took from the research was that low and lower soil moisture levels do the inoculant no good to the point of the odds of success being dismal, more dismal than I would have expected.

You're right. There are no absolutes - except in the lab where they are controlled for good reason. So, to Brooke I say, find another crop that will do better under the conditions you face.

There's another issue and it's the side effect of high soil pH. I didn't read the full research, but, rhizobium apparently are more vigorous when there's an adequate supply of molybdenum. It's deficient in soils with low pH. I understand some inoculants contain a small amount to overcome it, - that, and fungicides which apparently are of no or harmful value. Anyhow, I read that high pH soils tend to be more releasing of the micronutrient normally bound to soil particles in a low pH environment. And, while too little is bad, so too is too much. So, there it is. A bad hand of cards with lots of money on the table.

Yes, there's always moisture in the soil - somewhere, but there are many times when deficient to such a degree there might just as well be none.

See what I can learn by reading Habitat Talk! I love this place....

Thanks for all the input - very helpful.

When I plant my Iron and Clay peas (cow peas) next Spring (~May) I think I am going to try and do a small test plot of cow peas that I can irrigate right after planting as a test to see if they will form nodules after seeds are inoculated and planted. I have a limited drip irrigation system that I use for some young fruit trees that I can use to get some water to a small portion of the cow peas right after planting. This will help me confirm that my problem is indeed rhizobium failure due to lack of moisture. That way I know that I am doing everything else right.

I am not ready to give up on the peas just yet since they are surprisingly drought tolerant which is required for my area through the summer months when deer don't have many other forbs available. I guess if the nodules are not forming to help form nitrogen for the plant that I could bump up my nitrogen fertilizer levels to help the plant create more forage.

FYI -- my soil type is actually clay-loam, so it does hold moisture better than sandy soil that is common in east Texas. But the hot dry summer months will dry it out by end of summer, especially if we don't get any summer rains. So my Fall planting is usually done in dry dirt hoping for rain soon thereafter.

 

[Brookesmith]

UPDATE: I finally got around to calling the manufacturer of the inoculant I have been using for cow peas, etc. He confirmed that the inoculant can only survive a couple days at most in dry soil before it dies. So unless I get lucky and get a rain soon after planting in my dry'ish soil, I am wasting my time using inoculants.

FarmerDan nailed it.

Thanks

 

[S.T.Fanatic]

Does the inoculant actually have to contact the seed? Seems to me it would work to spread the inoculant on the plots before a rain no matter what seed you plan on planting. That way the bacteria is on the soil before you ever plant.

Tell me this wouldn’t work?


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