Banana stems are known to hold water for long periods of time. That's why we've gone to the extent of utilizing this stem for planting short rooted plants within the stock.
This done by placing some small holes at the stem using a knife or machete and adding a little soil.
This type of planting allows the plant to grow even during the dry season without irrigation and helps minimize resources and space.
Farming solutions to grow food for communities/family you won't always need expensive soil or broad-acre land in order to grow. You can sustain yourself with things you already have. This is best for short-rooted plants e.g. kale, spinach etc.