Ecology Action's GROW BioIntensive System
Ecology Action's GROW BioIntensive system gives us a lower limit on the amount of space needed to grow a complete diet: about 450m² (5000ft²) per adult. These folks sell their system, and I don't want to step on their toes, but they make available enough information through e.g. free PDFs and videos that it doesn't feel disrespectful to describe it a little bit here.
They have developed a set of eight principles:
- Deep Soil Preparation
- Composting
- Intensive Planting
- Companion Planting
- Carbon Farming
- Calorie Farming
- Open-Pollinated Seeds
- The Whole-System Approach
I won't go into details, please go check out their stuff, they have worked very hard and done a great job. Most of the principles are pretty self-evident (although there are many important details!), however, "Carbon Farming" means something very specific:
"Carbon" refers to plant material, also called “biomass”, that has a lot of complex cell structures and meets the criteria for mature material for compost building. Carbon farming promotes sustainable soil fertility by focusing on growing crops that produce a large amount of carbonaceous material (mature material) for composting. ... grow these crops in at least 60% of the cultivated area.
~ "A Farmer's Mini-Handbook: GROW BIOINTENSIVE® Sustainable Mini-Farming" by Margo Royer-Miller ( available here )
They also recommend a planting ratio of 60% carbon and calorie crops (e.g. corn), 30% high-calorie root crops (e.g. potatoes), and 10% veggies (salad fixin's). The high ratio of carbon crops is very important, as that's the key to increasing soil volume and fertility: you're not just feeding yourself, you're feeding the soil ecology.