The land is found, shelter is found, water is found, but the land is rocky limestone.
It won't grow much!!
Spirulina - 65 to 71 percent protein, one of the earliest organisms and considered an estremeaphyl
eight essential amino acids are found in Spirulina:
* ISOLEUCINE (4.130/o): Required for optimal growth, intelligence development and nitrogen equilibrium in the body Used to synthesize other non-essential amino acids.
* LEUCINE (5.8001o): Stimulator of brain function, increases muscular energy levels.
* LYSINE (4.000/o): Building block of blood antibodies, strengthens circulatory system and maintains normal growth of cells.
* METHIONINE (2.170/o): Vital lipotropic (fat and lipid metabolizing) amino acid that maintains liver health. An anti-stress factor, it calms the nerves.
* PHENYLALANINE (3.950/o): Required by the thyroid gland for production of thyroxine which stimulates metabolic rate.
* THREONINE (4.170/o): Improves intestinal competence and digestive assimilation.
* TRYPTOPHANE (1.1301o): Increases utilization of B vitamins,improves nerve health and stability of the emotions. Promotes sense of calm.
* VALINE (6.0001o): Stimulates mental capacity and muscle coordination.
Spirulina can be grown in a ten gallon aquarium.
Take out all the stuff inside and save it (it can be used). Put in a sunny place and fill with water.
Put in the Spirulina, you should let set for a day son the chlorine will evaporate (this assumes you are using a public water supply).
There are place to buy Spirulina.
Instead of listing now I want to move on to a couple other points.
You have the LAND, SHELTER. WATER. With water you can also do hydroponics in poor soil. You can grow in 2 liter salvaged coke bottles, buckets and so on.
Al this while you are creating terra preta in a trainable area.
"Terra preta (literally “black earth” in Portuguese) is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil, and stays there for thousands of years.  It is also known as “Amazonian dark earth” or “Indian black earth”.: