Broad beans

interesting Topic and you will get as many different answers as replies ! as I understand it you cut them off and leave in the ground .

Just plant the next crop around the old roots?

I'd like to ask a question about the nitrogen.  Ive pulled up all of my broad beans and I can clearly see the nitrogen nodules on the roots.  Should I just compost this with the plant, should I remove the roots and put them in a bucket to rot down separately or should I bury them in the plot out of the way?.

I dig the roots in with the nodules attached. Cut the stalks off at ground level and compost those. The crops I since put in seem to appreciate it.                                                                                                                                           

Although legumes do fix nitrogen from the air, the way in which subsequent crops may benefit isn't quite as straightforward as it seems:

Nitrogen Return to the Soil and Other Crops

The amount of nitrogen returned to the soil during or after a legume crop can be misleading. Almost all of the nitrogen fixed goes directly into the plant. Little leaks into the soil for a neighboring nonlegume plant. However, nitrogen eventually returns to the soil for a neighboring plant when vegetation (roots, leaves, fruits) of the legume dies and decomposes.

When the grain from a grain legume crop is harvested, little nitrogen is returned for the following crop. Most of the nitrogen fixed during the season is removed from the field. The stalks, leaves and roots of grain legumes, such as soybeans and beans contain about the same concentration of nitrogen as found in non-legume crop residue. In fact, the residue from a corn crop contains more nitrogen than the residue from a bean crop, simply because the corn crop has more residue.

A perennial or forage legume crop only adds significant nitrogen for the following crop if the entire biomass (stems, leaves, roots) is incorporated into the soil. If a forage is cut and removed from the field, most of the nitrogen fixed by the forage is removed. Roots and crowns add little soil nitrogen compared with the aboveground biomass.

Source of above quote, and further information:
http://aces.nmsu.edu/pubs/_a/A129/

Probably your good soil Surbie100 (and the bean roots must have made some difference!) 

That seems a bit farmery, where all of the plant is removed from the field.  What about when we leave the roots and those root nodules in the soil.  Those nodules contain nitrogen don't they? It has to go someware. 

I've tried them in several locations and had no real success. This year I really went for it with tons of horse-sugar, hence the 6 ft tall plants. Conclusion is that our springs up here are so late and wet that the plants are flowering ahead of the insect-boom leading to poor pollination. I'll give them one last go with a later planting. If still no good that's it