S Bengi wrote:
You want a nitrogen fixer/legume, this should be 90% at establishment and then culled/dieback to 25% at maturity
In the tropics, the possibilities are endless. Pigeon pea was mentioned earlier in the
thread. Now, I don't know which legumes you have in India, but I can give you an idea of the diversity by telling you about the Caribbean ones I know.
The most ubiquitous tree in the Dominican countryside is known as the "fence post tree' (
Gliricidia sepium). Literally every barbed wire
fence uses this for the posts, because all you have to do is cut vertical limbs off an existing
fence post tree, set them as fence posts, and most of them will take root and become trees themselves. As a secondary use, farmers will also cut its leafy boughs for
cattle feed.
In the open pastures, the most wide-spreading shade tree is the monkey pod (
Albizia saman). Besides providing shade (valuable in the tropics), it is also the best quality local
wood for furniture (except for mahogany, which is expensive and mainly for export). I have seen cow pats full of monkey pod seedlings (I have attached a picture), which tells me that its pods are another cattle feed.
Then there is West Indian
locust (
Hymenea courbaril). A local person told me it was "
algarroba," which means carob, and I did indeed find that the powder inside its pods could be used like carob. (The real carob (
Ceratonia siliqua) is also a legume.)
We have the tamarind (
Tamarindus indica), whose scientific name tells me that you have it in India, too -- so you surely know about its tart pulp, which, I now see in Wikipedia's table, is especially rich in Thiamine (that is, vitamin B1).
And that's just the trees! My point being that if you choose carefully, the legumes you put in for nitrogen fixation can serve additional purposes over and above that.