@llgecir43
I'm in a similar situation. I'm interested in power & participation related to environmental governance. Also a niche topic that intersects many disciplines. I applied to 6 PhD programs, all from varying departments...
PhD Geography - Wisconsin, Madison
PhD Geography - UT Austin
PhD Environmental Policy - Duke
PhD International Relations - American
PhD Behavioral Policy, Environment & Sustainability - Michigan
PhD Geography - British Columbia
To me, it's largely dependent on your career aspirations and advisors. I would like to remain in academia afterward. With this in mind, and with an interdisciplinary interest, I saw the individual program as less important. With a good advisor and strong research performance, I'm fairly confident that I will be competitive in many different academic departments - environmental management, geography, international relations, public policy, sociology, anthropology, etc. A lot of these departments hire from varying disciplines, especially if their background and research align with interests. I have taken some time to visit future dream schools and dream departments I'd want to teach to look at the credentials of current professors - this has been helpful in easing my mind. Their PhDs and research topics are all over the place. If you want to teach afterward, maybe do the same? If you want to go professional, perhaps go look at staff at your ideal companies and see what their PhDs are in? If they vary wildly, then you're probably safe no matter what and can pick the one that feels most 'right'.
For your particular interest in quant/econ/geography, I don't think business vs economics vs geography will matter all that much. This is just my opinion. With a PhD you will be able to customize your coursework to fit your needs and desires, and will probably get to take coursework across departments if you want. Pick a good advisor, good funding, and a place you feel you will be happy. Then let the rest happen organically.
PS - I'm from the state of Missouri, so know MU very well. If you have questions about living in Colombia / Missouri, happy to answer. Good luck!
Cheers, CR