Tag Archives: nitrogen fixation

Productive Polyculture Experiment

Sometimes it’s funny how things turn out. I have not been a fan of the ‘garden polyculture’ strand within permaculture. I think that it’s ok on a small scale, or where there is a lot of free labour available for harvesting, but it has never struck me as a way to grow significant quantities of calories. Strangely I seem to be coming back to the idea. It all started with confirmation of the yield increase from a grain legume combination. Not really a true polyculture, more of an intercrop, but the basis of my small scale grain growing experiments. Things have moved on a bit since then. Please note that I’m not going to be giving details of all of the plants that I am using in my experiment, or references for the information that has got me to this point. I want to be sure that it works, before publishing the results. There will however be plenty of links to help you think about your own polycultures, or cover crop cocktails.


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DIY Soybean Inoculant

My DIY Soybean Inoculant experiment was designed to create my own inoculant, to save having to order fresh commercial soybean inoculant each year. I described my reasons for conducting the experiment in my last post, Soybean Inoculant Experiment First Results.

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Soybean Inoculant Experiment First Results

Just a quick post to mention the first results of my Soybean Inoculant experiments. The experiments were to see if:

  1. Commercial soybean inoculant was able to be used for a second season despite the use by date on the packet.
  2. I could produce my own diy inoculant using soil from pots in which soybeans had been grown.

Soybean Inoculant

The reason that I need to use Soybeam Inoculant is that the native rhizobia are not present in UK soils. My reason for growing soybeans was to see if they reduced the incidence of scab in a following potato crop. I bought some inoculant from the USA, but didn’t want to keep buying it for four years until all of my beds had some soybean rhizobia present. The packet was supposed to be only good for a single season.

The Experiment

I planted up four Rootrainers with pre germinated soybeans, collected from plants grown last year. Three were planted up using soil from pots that had grown soybeans last year. The fourth had commercial inoculant sprinkled over the seeds when sown.

The Results So Far

Today I planted out the rootrainer that had the commercial soybean inoculant added. All of the plants had rhizobia present in root nodules, as can be seen from the pictures below.

soybean inoculant used to add rhizobia

Soybean roots colonised by rhizobia

The first picture shows the rhizobia in nodules on the roots of a soybean plant.

soybean root nodules

Soybean rhizobia colonising roots

The second picture is of the same roots but as a close up. There were not a lot of root nodules, but it has only just warmed up, so microbial activity would have been low until recently. As the weather warms up, root colonisation should increase.

DIY Soybean Inoculant

It will be at least a week before the first of the roottrainers with the DIY soybean inoculant is planted out in my new polytunnel. I will wait until then to see if my attempts to create my own inoculant have been successful.










Nitrogen Fixation (or Free Fertility)

Obtaining free Nitrogen, by using Nitrogen fixing bacteria, is something that anybody looking for a more sustainable way of growing should be aiming for. There’s plenty of it in the atmosphere, so why use energy, effort, and money to get it, when there is an army of microbes waiting to do it for you, for free.

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