Question answering is an interesting problem because it is not only about having an answer but also trusting the answer to be correct.
This is usually done through supporting evidence to justify the answer or by finding an authoritative source for it.
Now, what constitutes an authoritative source varies from community to community. In the case of Farmer Text Support, the informants we had access at the Randoms Hacks of Kindness hackathon said that subsistence farmers in remote villages were very distrusting of advice coming from outside of their community. Basically, they wanted advice from people whose livelihood also depend of the quality of said answers.
This view sparked the project, which stalled at the design stage but centered around text messages and a central server that matched questions to expertise.
The time for a SMS-based community QA might have passed but other types of community self-help using a similar design might be of use. The value to answers found within a community and distrust from information from outside can be found on many communities these days.