Inoculation: yea or nay?

Inoculants are naturally occurring bacteria found in soil. Legumes and the bacteria have a deal: The bacteria live in nodules on the root structure of legumes; the legume plants provide the bacteria with food; the bacteria take nitrogen from the air and make it available for the legume plant to use. If there is no bacteria in the soil, the legumes will take up nitrogen from the soil just like any other plant.¹

Some soil has the bacteria; some doesn't. If a legume has been planted in a certain location for a harvest cycle, the bacteria from the plant should remain for 3-5 years. If a location hasn't been used to grow legumes, odds are, there are no bacteria present that the legumes are buddies with.

For large scale farming, the cost of inoculant is in the $5 range for an acre's worth of seed. To add nitrogen fertilizer to that acre can be in the $150 range. You can see that it's much more cost effective for a large scale farmer to make sure the legumes can make their own nitrogen (by inoculating) rather than providing nitrogen by fertilizing.

Now let's look at backyard size gardens or container gardens. If your growing medium is properly fertilized, your peas and beans can grow just fine without being inoculated. Many of us have done it; I never heard of inoculants until my fourth year of SFG. I'm going into my sixth year, and I still haven't used inoculants.

Are inoculants valuable for the home gardener? I can't find substantial proof one way or another. I keep finding anecdotal stories, and resigned comments such as this:

Legume inoculants may or may not be necessary for maximum yields, but professional farmers use it, so I figure it makes sense to hedge my bets.

We have already seen that professional farmers inoculate because they can't afford not to. And then there was this from the website of a big seed supplier...

Many people grow successful stands of legumes from seed that was not inoculated. However, inoculating the seed is good insurance that the plant will be properly equipped to grow to its maximum potential and compete.

I am at a loss to find studies that show consistently improved yields for backyard gardeners when using inoculants.

Are legumes less efficient at taking up nitrogen from soil than other plants? Does cool soil, which peas are usually planted in, restrict the uptake of nitrogen? Are legumes a heavier feeder of nitrogen than most plants? I don't know. I suggest that MM provides sufficient nitrogen for peas and beans because I don't have the obvious signs of nitrogen deficiency. I have no way to compare my harvest quantity. In the ANSFG book, Mel doesn't say anything about using inoculant for beans, and for peas, he says: "inoculate to give them a boost". He does not say exactly what that means.

If you are planting beans or peas for the first time in new MM, you could do a comparison test. Plant one half with inoculated seed; plant one half with seed that was not inoculated. See which one does best, and let us know.

If you want to try inoculating:

• A nursery is more likely to have inoculants than a big box store, or get it online
  
• Each legume has a specific bacteria that it likes ie you would get one type of bacteria for your peas, and another type of bacteria for your beans
  
• Inoculants are living organisms, and have an expiration date; they won't keep a year
  
• Protect your inoculants from excessive heat, dessication, and direct sunlight
  
• Most inoculants for home gardeners are in powder form
  
• Generally, to inoculate, you dust your seeds with the inoculant. It's that simple, but do read and follow the instructions on the package!

As an example, here is a catalog page for inoculents from Johnny's Seeds.

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Note 1: Go here to learn more about the process of nitrogen fixing.

I always add it to peas, beans and clover, but can't say whether it helps or not as I've never not added it.

I figure... it's cheap insurance.

I did use it for the first time last year. *Seemed* to work great for my spring peas. I put it on all the peas.

I did do a test with my fall beans crop. I inoculated a 4x4, and just planted the other one. The result was no difference. Both were a huge crop.

Squat,

Had you grown beans in this specific area previously?

Just curious if that makes a difference?

I wasn't very happy with my pea harvest last year. Was it because:

A. I didn't use Mel's Mix?
B. I didn't use inoculant?
C. The kids ate them behind my back?
D. All of the above?

@Furbalsmom, they were new boxes. In the spring, they had their first crops, neither were legumes. I did my 'lil experiment in the fall.

Thanks, Squat.



I had heard that innoculant was most helpful for an area that was getting it's first legume crop.. Appears it did not make a difference here.

Interesting Boffer.
When I first heard of them I though it was the mould spores you can use that enter the plant roots interact with the nitrogen in the soil giving the plamnts food... looks like I need to research much more .

Plantoid, I'm surprised you haven't come across inoculants. Any chance you know them by another name? Or, maybe the bacteria are native, or more widespread in GB due to being farmed for 1000s of years?

There is a fungus spore that we can buy .. mainly used when transplanting small shrubs & trees once you have dug and manured the hole.
..
You're supposed to sprinkle a few hands full on top of the bare roots , cover with good soil then lightly tread the soil on to the roots before back filling the hole.

This place we live in was built on a hillside on virgin clay .. no known habitation or cultivation here for donkeys years.
I'm told that since the place was built 32 years ago no one has ever tried to garden as the soil is stickly heavy blue clay & rubble back fill .

For the last five of years I modified the clay with manures ,sand ,compost and gypsum to get 18 inches of rubble free friable soil .. I've grown a load of peas and not noticed any reduction to those grown elsewhere in any of my other homes.

I had very goods results useing inuculent with my soybeans last year Did not inuculate my peas and they did rather poorly. Each requires a different one. It is impossible to tell with all the other vairibles if that had anything to do with it but still I will use it evey time I grow legumes in a new place now

I've done a bit of reading about the use of inoculants today.
It seems a cheap biological way of getting nutrients into a plant , it says you cannot over use the inoculants as they don't cause any poroblems.
Though I wonder what the real long term effect on /in the ground will be for nature has it's own way of balancing things out in the course of time?

It appears they are not used much in the UK outside of the crafts of professional horticulturists, propagationists and nurserymen .

So far I haven't found anything about them being used in UK farming as crop enhancers.

I was asking at the box store about inoculates yesterday!

They did not carry any. However, they said if you use any of the Kellogg's planting mixes products, the inoculates are already there.

I do use Kellogg's NRich compost to replenish/refill my rose beds (they get blow out/ washed out over the seasons). As an added bonus, it comes with red wriggler worms! But it wouldn't have inoculates (it's not a planting mix) and it isn't in my veggie garden.

The only real way to tell if the nitrogen had changed is to soil test before and after. Ferry-Morris sells a kit for $3.27 (pH, N, P, K). Very easy to use. Instructions (and corrections) are included. (DOH! I just realized while Kellogg's calls it this!)

With my new plot, I did soil test, and it is very high in N. On a whim I tested my rose beds and a patio area that has laid fallow for many years after growing....peas & beans! It was N dead. No wonder I didn't need to weed it all these years! Just the occasional Orange Oxalis would pop up near the hose. A AloeVera at the far end loved it.

Commercial farmers can't afford not to inoculate and use chemical fertilizer because tillage destroys the fertility of the soil. If your soil is healthy to begin with, you shouldn't need to add anything outside of organic material.

Having said that, I wanted to see myself, so I bought some inoculate and used it on my peas this year. They seem to be doing about the same. However, I'll be letting the plants rot in place(not the actual peas mind you, they're too yummy) since I planted them in every other square and will be planting tomatoes in the open squares this year(as another test about using legumes to add nitrogen).

While these tests are just about pointless if you do SFG by the book, I'm just a curious sort of person. I'm fairly sure that if I just threw the spent pea plants onto my compost pile, I'd end up getting most of that nitrogen(or my banana plant and lemon tree would, since I planted them close to the compost pile).