[AlaninCarlisle]

I keep hearing that we should leave runner-bean and other bean roots in situ when we have finished harvesting from them so that they can release nitrogen into the soil.

The question I have is about how much nitrogen is released. Is it an amount any more significant than that from, say, a handful of fertiliser or a spadeful  of rotted muck? In fact, is it worth doing at all?

[mumofstig]

There is some debate about how much is actually left after pods have been formed. In fact some more recent reports say that none is left, all of it being used up in forming the pods.

It's easy enough to cut the stalks at ground level and leave them to rot in the soil, which is what I usually do 

Here's a dwarf bean root that did get pulled up, so I could take the pic, showing the nodules that form the nitrogen while the beans are growing.

[surbie100]

I pulled the dwarf bean plants the other day after saving pods for seed - none of the roots had nitrogen nodules on them anymore. I'm assuming they were used by the plant.

[AlaninCarlisle]

I think what I'll do is uproot the plants totally and then put them in the compost. Whether or not any nitrogen is released will become a redundant issue as it might as well be in the compost as in the ground. This will give me two advantages:
1 I can spread the compost where it's most needed
and
2 I won't be faffing around with secateurs when I've finished harvesting

[Ema]

I just find they get in the way of the next years crop and don't rot down completely over winter. Also last year I had bean blight quite bad so bin bagged the lot and took to the tip