Sunday, May 10, 2009

Nitrogen fixing plants

I have always heard the phrase "nitrogen fixing plant" and could tell you that legumes are indeed "nitrogen fixing plants" - but I 've never given a second thought about how a plant actually sets nitrogen. Hubbie is growing soybeans (a legume) this spring and pulled this plant up to check it for nitrogen producing nodules. Check it out, close up - This little guy has three nodules inside the black circle.
I must admit I didn't think about it again until I read Zanthan Gardens' post on saving bluebonnet seeds. She tells us when we're ready to clear out a patch of spent legumes, do not pull the plants out by the roots; cut them at ground level. This keeps those nodules in the soil where they'll help enrich the soil. Nasturtiums are also legumes - Sure wish I'd read Zanthan Gardens post earlier - this morning I pulled out all the dying and drying nasturtium plants. Live and learn.


Sheila said...

Very interesting! I never knew that! Thanks for the lesson! Happy Mother's Day!

Corner Gardener Sue said...

Thanks for the information. I knew about beans, but didn't know about leaving the roots or that nasturtiums were legumes.

Rock rose said...

What I usually do is to pull out the plant and then pull off the nodules and put them back in the soil. Bluebonnets always have huge nodules.

Jan said...

Interesting to actually see the nodules that I have only read about.

Always Growing

Mary Beth said...

SHEILA - One of my favorite things about gardening is that I am constantly learning something new - and re-learning things that I only thought were true.

SUE - Well, your comment on nasturtiums has sent me on an information search for something that states they are legumes. I took that for fact when someone stated it - now, I'll see if I must eat my words.

ROSE - glad I didn't lose the benefits of those nodules. They are safely resting just beneath the mulch. What color are bluebonnet nodules? I read that immature nodules are white, they become red and orange as they are producing, and then become green when their work is done.

JAN - I'll be pulling up more legumes to see what's happening beneath the surface!