Looking at this as a thought experiment. Hmmm...
Such a large scale disaster would be beyond a challenge. I think it would be a daily struggle for survival.
Politics, environment, even zombies (or their social equivalent) would be elements involved in one way or another. Rather than get into questions of how you survived the disaster to begin with, let's examine the scenario and find elements which can lead to problem solving methods in our undestroyed world.
Let's set up some parameters.
I'm going with the assumption that setting up an exclusion zone around the contaminated area is not possible or practical. Perhaps exclusions zones would exist for the areas of highest contamination, leaving less contaminated areas open. For whatever reason, contaminated
land must be made productive. This scenario would demand that the contaminated area would be a significant portion of a continent and that evacuation is not possible because of logistic or political reasons.
For the sake of discussion, I'm going to
project that some detection and monitoring equipment is available from universities, laboratories and government facilites, and these have been used to identify the uninhabitable areas and the depth of soil contamination in habitable areas.
I'll take the further step of assuming the crisis has completed it cycle and further contamination is from atmospheric particulates.
Considering material half-life, prudence dictates the land would not been worked for the previous year. Furthermore, it must be assumed that the level of radiation has reduced to a point that daily outdoor exposure is not life threatening. This level of exposure says 50-100 years will be the duration of the emergency. Anything more than that and the survivors will have eeked out their stone age existence in misery.
Elements to consider:
Soil
Removing the top 2-10" of soil will significantly alter the normal ecosystem. The top 6" of soil is where most of the organic matter and microbes reside. Replenishing these elements will be imperative.
Water
Surface water would contain radioactive particles as a result of runoff. Rainwater would also have residual particles for the next 2-10 years, gradually reducing, but not being eliminated entirely.
Plants
This gets split into 2 groups: new plants, started since the work on the land was started after the event, and old plants still in place since before the event.
Livestock
If people are around to work the land, it can be assumed that livestock are also around.
Fertility
If evacuation is not possible, I would think the importing of fertilizer/pesticide/herbicide feedstocks would not be possible. Crop inputs would be produced within the nation or must be locally sourced. Everything available must be utilized.
Protection
Given that time has passed, the remaining radiation would be gamma rays, sourced from the ground, atmosphere and rain. This is a line of sight issue and an issue of surface decontamination. Atmospheric exposure is a concern of respiration. Direct exposure from stratospheric particulates would be mitigated by the mass of atmosphere between the ground and the stratosphere. Continual exposure of low level radiation must be addressed, particularly with the young.
Now we need a plan of action.
I think the first step would be to prepare the site for long term use which mitigates continued exposure of the plants, animals and people. Removal of the topsoil will be a major undertaking. Once removed, it would need to be covered with uncontaminated material to serve as an absorber, blocking the release of radiation from the heap. Dig out a big deep pit, dump in the contaminated soil, cover it with the dirt dug out of the hole at the start. One big bad pit would serve a wide area, not just a single farm. Another option would be to dump this soil in a river to let it wash out to sea. Dumping in a deep lake saves work but would affect the life in the lake.
Next up is a perimeter. A mound of uncontaminated soil would be needed to block horizontal exposure from land that has not be scraped. 10' high would be in the ballpark. This would give it a base width of around 30 feet. This gets built around the entire production area. To maximize the area inside compared to the length of this
berm, the site would be round. This is the least work for the area being protected. Natural barriers such as hills can help reduce the work, but the hill would not be usable. An island would offer an advantage here. The idea is to hide the entire place such that no, or as little as possible, outside land within a couple of miles is visible from the inside or the shielding is ineffective.
Protection from rain is the next issue to address. Cover the whole place with a dome? You need the rain. The volume of water needed for raising field crops is huge. Keeping the rain from falling on the field would be desirable. One method would be to cover the site with a transparent barrier. Another is a fine netting which will redirect the rainfall for collection and filtering. The netting can also offer protection from
solar UV if the ozone has been affected. Maintaining this overhead covering will be needed for the first few years. After that, fallout contamination would be tolerable. Storing rainwater would require a considerable retention area. This can be outside the perimeter wall. This water would be filtered through gravel/sand to remove contaminants. The filtering material may need to be replaced, but without measurements I can't say much more.
Housing is covered with a deep layer of uncontaminated soil. Roof structures would need considerable attention. Ideally, incoming air is filtered, with the filters being replaced regularly. This has the advantage of maintaining a stable temperature inside. Other structures designed for human or animal habitation would also benefit from such a shield. Locating these structures in proximity to the perimeter berm will save some effort.
Water for consumption, cooking, bathing and cleaning would be served by a well.
Power would be tough to come by. If the problem was the result of a nuclear plant disaster, chances are good that electric generation is constricted. If war, it can be estimated that power generating plants, transmission and control systems are destroyed. Power for the well would need to be generated on site. A windmill on top of the perimeter berm,
solar panels, muscle power. Indoor heating is not needed or is minimized, lighting is done with mirrors, cooking is primarily solar.
We are ready for crops and livestock.
Here is where it gets interesting. Because of the nature of this scenario, space and resources will be a premium. The residents would be living off the land, using what is available, wasting nothing, bringing in as little as possible from the outside, and have practically nothing to work with. Getting the absolute most production out of what is available will be the rule of thumb. We'll need to extend the growing season as much as possible. Crops will need to be planned to provide as diverse a diet as possible, providing calories and nutrition. They will need to come to harvest continually so as not to tax the available labor. They must get more
energy from the food than they put into raising the food or they starve to death.
A
greenhouse offers an advantage here. It does not have to be excessive, but there would be a space requirement per person. Effective design can keep it warm
enough in the cold season for some production which will maintain vitamin production for the health of the residents. For seed starting, the advantage is considerable. Minimal soil and water are needed, and labor is minimized per plant. Conditions are as controlled as possible, giving the plants a solid head start. Once space in the growing beds is made available, a new plant can go directly in, with a several week head start. Condensation in the morning can offer a clean water source. I think placement on the north side of the site, built into the berm would ideal.
Planting areas would be enhanced greatly with hugelkulture. The
wood going in would need to be stripped of bark outside the berm to remove contaminants. The wood inside would still be suitable for use. Legumes would be vital to improve the weak soil.
Root crops would help break up the hard subsoil which is now at or near the surface. Plants would need to be closely spaced to maximize production and minimize water demand. Vertical growing methods would be required. Moisture retention with a deep mulch would be critical. Hair, feathers, lower leaves, washed materials, rocks, sheeting, everything that can be found. Great care and attention would need to be given to every inch of soil.
Establishing a microbial community in the soil would be paramount.
Compost tea would really help kick things off. Worms would be a key element. They replace the work required, process whatever inputs are available, and transform soil into topsoil. The obstacle would be finding and gathering uncontaminated material. Water plants, being shielded, might be a solution. Bat guano and cave algae would be a gold mine.
Humanure would be a highly prized commodity. Composting every available material sourced from inside the perimeter would be a major endeavor. Leaves from the branches just after a rain could be rinsed to provide for more material. It will take much effort to get organic matter into the perimeter from outside sources, but you gotta have something to work with. Anything coming in from outside would have to be heavily rinsed, and the water would need to be purified-how about solar for that.
Reducing the workload,
chickens can do much to prepare a growing area. Contain them, they'll scratch up an area, keep the bugs down, and add droppings. They also offer a source of protein for the plate. It would be necessary to track their genetics, culling as necessary. Until they can be free ranged outside the perimeter, they will need to be fed. They'll be few and skinny. I do not have a solution to offer for large livestock and their land requirements.
Tank raised fish have a place. With clean water, they are well shielded to begin with. Worms would offer a fine food source. Guts give the
chickens a dietary
boost. Cycling the water through plants will filter it, keeping it fresh without replacing volumes. The plants get the benefit of a high nitrogen input. As many systems as possible will need to be in closed loops, the waste of one part being an input for another part.
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Just with this short piece of a thought experiment, I find that in a scenario such as this, a wide array of
permaculture techniques offer key advantages.
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