[VegPlotter]

Hi Everyone

I know I am meant to leave the roots of my broad beans in to provide nitrogen to the soil, should I also be leaving the roots of my runners and fine beans in?

Thanks for your help
Julia

[sonnycbr]

Any leguminous plants, peas/beans etc will fix nitrogen in the soil so its a good idea to leave as much of the root system as you can.

[VegPlotter]

That's great 

Do I just let them rot down over the winter and then dig in in spring?

[stompy]

yes 

[Yorkie]

I recently read an article / saw something on TV recently (can't remember which) about research into nitrogen fixing by leguminous plants (peas, beans etc).

Apparently, the nitrogen is at its maximum before the plant starts flowering / setting beans.  At that point, the nitrogen in the roots nodules gets transferred from there up to the above-surface part of the plant.

So, whilst it is still beneficial to add organic matter to the soil, the nitrogen left behind isn't as great as previously thought.

[sunshineband]

But it won't hurt to dig them in anyway 


(Didn't know that Yorkie  )

[Carollan]

Yorkie,I heard that on Gardener`s Q Time a week or so ago.....I was quite miffed as I have always religiously left the roots of peas and beans in the ground.......they said only about 5% of the nitrogen is left fixed in the ground,or some such low amount. Quite disappointing eh.

[mumofstig]

Research suggests that you have to dig in the whole plant, as you would green manure field beans, to reap any benefit.

[sunshineband]

I guess I'll stick with chopping the stems of the runners into the compost bin 

[DD.]

Gets back in one way or other!

[sunshineband]

Gets back in one way or other!

Awwwww Yuss 

[Salmo]

The roots of runners can be quite big and tend to get in the way of cultivations unless turned right under. If you pull them most of the fine roots with the small grey nitrogen root nodules usually stay in the ground anyway. If they go into the compost any root nodules add to it. I do the same with broad beans.