The African keyhole garden is different from the Mandala design since the center of the raised bed is dedicated to nutrients and the access to the plants is done from the outside.
This example of a structure is made with bricks having no stones in Bahia Atlantic border.
Note the disposition of the bricks to increase the wall cohesion.
The V shape inclusion is the access path to the future basket of nutrients.
Here we use hardwood to create the basket frame.
The frame is hold together using wild vine harvested in the forest.
We add cardboard on the periphery to reduce weed invasion.
The next step is the construction of the raised bed. You may find many recipes on internet about the different layers; every one has his own method; …compost, mulch, brown and green manure, ashes, biochar, etc… The last layer is made of mulch, for example the leaves of a leguminous tree to provide with nitrogen and protect from the sun.
Compost, mulch or manure is added in the basket. The basket is regularly fed by organic matter (mulch, kitchen scraps, animal manure, …). The idea is that watering the basket will bring the organic nutrients to the raised bed over time. The basket design acts as a nutrient chamber easy to fill where composting is accelerated and humidity better kept as well.
You may plant a guild of Papaya, dwarf banana and Pigeon Pee.
The African Keyhole is well adapted to hot and dry places