For nitrogen fixation, with very few exceptions, beans are best and indeed, all leguminous plants.

Beans, in particular, are compatible with most plants, although the allium family is highly antagonistic. Try it. Plant beans next to garlic - and watch them sulk.

In the legume family, that of broad-beans, or fava-beans, is probably the best nitrogen supplier I have ever seen. There are certain periods throughout the plants growth, where, not only can you SEE the nitrogen nodules, but, they are actually able to be weighed.

When considering the use of nitrogenous plants as companions, in vegetable growing, a decision must be made as to whether or not the bean is there purely for the nitrogenous qualities, or, if a produce return is expected also. I have always felt that any produce is a bonus, but never actually expect any due to the general treatment the legumes get.

Meaning, if I am using legumes as nursery, or shelter plants for another crop, as the beans start to take off, they are pruned to two-thirds of their size. The prunings become part of the existing mulch.

Apart from keeping them manageable and preventing competition with the main crop, this causes the plants to shed their nitrogen, at times producing some remarkable results.

Peanuts, also a legume (viable seed readily available at the supermarket as 'raw peanuts'), will grow with anything - then probably smother it.

This is a peculiar member of the legume family for the fact that the seeds are produced underground. Not all that dissimilar to subterranean clover, by the fact that it, too buries its own seed, the nuts.

The plants grow to about the size of a basketball, I have found it to be too competitive for space, to be planted in close proximity to most small-crops. However, it does relatively well with quick growing, robust plants like corn, daikon and artichokes, both globe and jerusalem.

Highly susceptible to white-fly, I have had a disastrous attempt at growing it with tobacco, also a white-fly favorite.

In order to produce more nuts, the plants are traditionally 'hilled' to assist with the seed burying process. I have found that, not hilling them, but using them as a 'cut-and-come-again' supply of readily available mulch material, keeps them manageable in a vegetable garden.

I have found an enormous amount of benefit, and amusement, from growing them in poultry forage yards. Chooks aren't all that interested in the growing plant, other then an excellent place to have a dust bath under - and can at times kill the plant. However, once the plant is pulled at harvest, poultry can be kept amused all day long, scratching for the pods, then trying to extract the nut.

The Arhae Pea, prime dahl producer, can grow to 12 feet and makes a marvelous
windrow plant. Semi-deciduous, producing masses of pods on each seasons new
growth, after harvesting is cut back hard to where the branching begins,
reshooting each year, for about 6 years.

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