Do legumes release nitrogen continuously or only after they are killed?

Do nitrogen fixing plants release nitrogen continuously? Or do they store all of the nitrogen in their own cells, only usable to other plants after they are incorporated into the soil?

I've been playing around with the idea of planting dutch white clover as a permanent living mulch as it only grows 6-8inches tall, is perennial and fixes nitrogen. However, if the cover crops must be killed in order for the fixed nitrogen to become available, I might consider an annual or winter-killed clover.

Clovers can share while alive, but it is not the hundreds of pounds per acre of a cover crop turned unto the soil. An occasional mow or scythe (chop and drop) will release a lot of N without killing the clover.

R Scott wrote:Clovers can share while alive, but it is not the hundreds of pounds per acre of a cover crop turned unto the soil. An occasional mow or scythe (chop and drop) will release a lot of N without killing the clover.

exactly the answer i was looking for. thank you.

My red alder trees are not legumes, but they produce more nitrogen than clover would. The leaves fall in October and November but the tree comes to life again in March.

Dale Hodgins wrote:My red alder trees are not legumes, but they produce more nitrogen than clover would. The leaves fall in October and November but the tree comes to life again in March.

I imagine alder wouldn't play well with sun-loving crops though. Low growing clover wouldn't compete for sunlight.

i've been wondering about this too. i'm hoping to grow mung beans, lentils, chickpeas, red kidney and broad beans in containers. will they produce their own AS they grow? or will they 'fix' nitrogen only when they're mature? i've tried to grow pulses many times and always failed but i'm determined to succeed in 2019 (and i cheated this year since a friend germinated a few for me).

hau Pusang,  That will work quite well as long as the containers are large enough to support the root system of what is planted in them.
Usually the containers should be able to hold at least 5 gal. of soil per two plants if that helps on sizing the containers better.
Drainage is also a key factor, as is making sure the soil doesn't dry out completely and you will want to use fish emulsion and other "natural" fertilizers about once a month on each container, more often if the plants are heavy fruiters.

N fixers generally utilize a bacteria that forms nodules on the roots for their home and these bacteria gather the nitrogen that is pumped down to them from the leaves.
For most plants it is the leaves that do the nitrogen gathering from the air that passes through their stoma as they go through the process of respiration during daylight hours.
Try to get seeds that have been inoculated, those will already have the right bacteria applied on the exterior of the seed coat.

Redhawk

Thanks so much Dr.Redhawk. My pulses will be in zone 1 (right outside my bedroom window) with all my other edibles so they won't ever dry out.  5 gallon minimum container size is noted, and i will try to bring back some fish emulsion from the weekend market. Will also be using my usual woodash and pee solution - that'll work too, right?

Hi Pusang,
what i gathered from people on permies and the book Teaming with microbes is that legumes form these nodules on the rootssystem which contain bacteria that take N2 from the air and bind it into NH4+ if i remember right, anyway, something with N, the plant needs it to grow healthy stems, chlorofyl and DNA. The nitrogenfixing bacteria do this in exchange for sugar the plant transports to their nodules.  Some kind of lodges inside the plant save from predators. If you chop the legume half down they self prune their rootsystem, i forgot why, but this leads to an uptick of these bacteria in the soil. Which just continue fixing nitrogen. Also you get the bonus of having this foliage which you can use as a mulch/ soilbuilder/ compost, after breaking down it will add nitrogen to the soil. The plant will soon grow back and grow it's rootsystem again. When the plant dies, all the nitrogen fixing bacteria go back into the soil and you can keep the seeds to have more plants the year after.
Sometimes ,especially in rich soils these nitrogenfixing bacteria are hard to find, leading to stunted growth. To be sure the plant has them in the rootzone, you can buy them, it looks like a yeast and dissolve it in water and just soak the seeds in it before planting.
I never do that, and checked the nodules on my clover, pretty small things, and if you cut it right through and the inside is red it means the nitrogen fixing bacteria are in.
I might wuzz up some clover rootsystem with nodules next time to make sure the bacteria are in next time. Anybody did that? Saves money.