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Old 04-12-2019, 02:16 AM
Gelrir Gelrir is offline
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That low number of farmers (in 21st Century U.S.A.) is related to global trade and industry. Daidalos has developed high-yield crop species in several areas, it seems. The community will have to produce machines locally, however (there's no hint of trade for such things).

In 2015 United States there were 1.25 hectares of agricultural land per person; so for 6,000 persons it's 7,500 hectares.

FERTILIZERS, PESTICIDES, ETC.

A hectare of 2015 American agriculture gets an average of 137 kg of fertilizers (phosphates, nitrates, and potash); and a few kg per hectare of herbicides, insecticides and fungicides. Daidalos clearly has a very active chemical industry (especially for a nation with one working oil well).

In the 21st Century6, phosphate rock is the raw material for most commercial phosphate fertilizers. Hydrogen from natural gas is a major component of ammonia production (which in turn feeds nitrogen production); nitric acid production also limits this. Potassium chloride is the usual source for making potash fertilizer; for the U.S., it mostly comes from Saskatchewan.
PHOSPHORUS

Could be made from soy husks, rock phosphates (if available), urine or bone ash; about 1% of animal live weight is phosphorus, and 85% of it is in bones and teeth. Used in chemical preparations, in steel and bronze production, for making matches, for making pottery, in baking powder, and in limited quantities for fertilizers.

Production of white phosphorus from urine (using charcoal or silicate sand) is easy. Red phosphorus is obtained from white phosphorus be heating it to 482 F in an container entirely free of air; this is a delicate operation. White phosphorus is very toxic, and liable to catch fire in air; it should be stored in mineral oil or water. Red phosphorus is stable in air.

If sulfuric acid is available, a more efficient process can be used to produce phosphorus from phosphate rock or bones. The bones or rock are dissolved in sulphuric acid to give phosphoric acid and calcium sulphate as a by-product. The acid is concentrated, mixed with 25% of its mass with carbon, dried in iron pots to a black powder and then distilled over and over in clay retorts. It is condensed into 10-15 kg blocks called 'cheeses'. After refining and casting into sticks (all under water to prevent it catching fire), the product is ready to be shipped, stored in water or mineral oil.

AMMONIA

Production of ammonia might be achieved by heating and distillation of nitrogenous plant waste, animal and human dung and urine. Guano (sea-bird dung) is particularly rich in ammonia. If you've got coal, ammonia can also made by coal distillation -- distilling one ton of coal produces 700 kg of coke, 100 liters of ammonium hydroxide, 50 liters of coal tar, 400 cubic meters of coal gas (used for lighting and heating), 30 kilograms of sulfur and about 10 kilograms of vanadium pentoxide.

NITRATES

These might be produced in compost piles of manure, ashes, straw, urine etc.. These "saltpeter plantations" willl be supremely smelly, and thus several kilometers outside of town; usually near farms with lots of livestock. Potash is (in essence) combined with the nitrates to provide the potassium component of potassium nitrate, used in turn for making black powder. For a VERY crude first approximation, a barrel of potash combined with the nitrates from the plantation produces a barrel of potassium nitrate.

Since potassium nitrate is 75% of black powder by weight, a barrel of it (~200 kg) will end up being part of 266 kg of black powder.

POTASH

This can be made at "asheries", for chemical use and for fertilizers, brewing, bleaching textiles, black powder production, glassmaking, etc.. The production process starts with burning hardwood trees and leaching the ashes in water. Partway through the process, you get lye (useful for making soap); this is further boiled down to make potash. Leaching the wood ash, and the conversion of nitrates to potassium nitrate (aka saltpeter, or nitrate of potash), creates a lot of water pollution.
FARM EQUIPMENT

Tractors, planters and harvesters are an important part of modern farm efficiency (both in terms of yield per acre and number of persons required). In 2007 the number of wheel and crawler tractors (excluding garden tractors) in use by agriculture in the U.S. was very close to 1 per square kilometer of agricultural land.
An example of an Iowa corn and soybean farmer (the farm is operated by the owner, his son and one employee): they need a semi-truck, a tractor, a planter, and a harvester, along with various towed or attached items, all to deal with 1400 hectares of land. These vehicles have to be replaced every ten or fifteen years; some are shared with other farms, but other vehicles not listed are leased or borrowed temporarily.
So, it's pretty much one "big equipment item" per farm industry person (which sort of matches the whole "mechanized farming" concept); so you need 60 to 75 large motorized vehicles. Combine harvesters weigh from 1.5 to 25 tons usually; so these are "car or truck" size vehicles. If they're replaced every 12 years, they need to make 5 or 6 per year. Thus there needs to be several assembly lines (for tractors, combines, planters, and trucks); a steel mill to produce tubing, sheet, structural, etc. steel; a source for rubber tires; fuel (methanol or whatever); lubricants; glass; wire; batteries; etc.

LOCATION

The scenario sort of implies that all this high-yield agriculture is in the San Gabriel Mountains, which is a little odd. Clearly the environment has changed (there are redwood forests everywhere). It's unclear how much the Daidalos community makes use of the flat land between the mountains and La Crescenta (probably Burbank, Glendale, Pasadena, etc.).

--
Michael B.
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