RE: Agriculture: Look at Petra in Jordan- HUGE trading city in Roman times, but climate changed and city was abandoned. Desert doesn't necessarily mean sand dunes. It can be arrid plains (Peru) or sparse scrubland (afghanistan). The status of the city as a tarding post can grow out of numerous things, the oasis not being the least. Maybe theres a religious site there that attracts pilgrims? (Mecca). As someone mentioned, irrigation form the underground aquifer is a common way to raise crops. Good plot hook too. "Our water has stopped flowing!!! Why?"
Looking for advice on the size of a city
- Thread starter Asmor
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Asmor said:
8,000 makes sense and would call this a city by medieval standards, a small city by Roman standards.
If they are planting wheat seeding 2 bu/acre with an average yield of 4:1 (a good conservative medieval tech number), you'll need 2 ac per person assuming 12bu year to feed one adult human male. This is eating real good by medieval standards basically a good 2000 calories a day by bread alone. Since it is also wheat they'll be eating like medieval nobility. Add in goats, figs and sheep you'll do well.
If they grow what was the common food, spelt, emmer, millet etc. you'll get higher yields and basically be able to feed 1 person per ac. Some of these plants are also more resistant to salination, a concern with extensive irrigation.
Assume an acre per person for cultivated land (no rotation but with all those caravan animals manure/fertilizer shouldn't be a problem) will give you fields extending about 2 miles from the walls in each direction using 8,000 acres, 1 square mile=640 acres. Which is really not that far as the horzon is 3 miles for a person standing on flat ground. So you'll certainly see the desert from the city gates.
Animal fodder is probably just as much a concern as food for people, with all the caravn animals going by. There are plenty of rangeland web sites from various agriculture departments that can tell you how many AUM (animal unit months) a given acre can provide, nd guidelines for estimating such based on ground cover. 1 AU = 1000 lbs of animal.
All of this with average soil and basic medieval tech/Roman tech. Add in better soil, great weather, better plant varieties, better fertilizer, each improved factor can increase yield 20-50%. Of course if any of these are for the worse, they each can decrease yield by 20-50%.
Add in seed drill, horse-hoes and cradle scyhtes and things get much, much better. Row cropping by seed drills and horse-hoeing can increase your yields by 75-250%.
The Grackle
First Post
Forget farming. The population would mostly depend on imported cattle and grains for nourishment. It sucks for the city to be dependant on outside food sources, but that's what they get for living in a desert.
Nyeshet
First Post
Good point. In a magical setting - especially a (typically high) magical setting like core D&D - there are numerous solutions to everyday problems. The earthen (or even stone) walls that surround the town could have been raised from numerous castings of Move Earth, Wall of Stone, etc. Move Earth could be used to begin with, surrounding the large town / small city within a week or so if 3-4 casters have the spell and work every day at it. The walls would be ~ 30 ft high, 30 ft long, and 10 ft deep - per casting. With 3-4 casters working at it, the wall could be 30 ft deep (normal for ancient and even middle ages times). It would take ~190 castings to surround a settlement one-quarter mile in diameter with such a wall.
Wall of Stone can be used to create a 5 ft by 5 ft by 10 inch block (by a tenth level caster). Or, if a more square block is wished, the spell could conceivably be used to create a cube of stone ~33 inches to a side. In all likelihood, it would be better to create the 10 inch five foot slabs, buttressing them with thick walls of earth (from move earth) on either side. Move Earth may not sound like much, but recall that the walls of Babylon were not (early on) stone. They were baked earth, perhaps with some straw mixed in. All in all, given one years time, a contracted group of, say, 4-5 9th level wizards, could easily complete the job. And if the trading city is prosperous enough to have a steady population of ~8000 in a desert, it should be able to contract such a group easily.
Water is never a major issue. A casting of Wall of Ice by a seventh level wizard or sorcerer will create a cube of ice about 8.3 feet to a side. After that melts the resulting mass of water is enough to fill an volume ~8.12 feet to a side. (The ice melts automatically after 70 minutes, for a 7th level caster.) That is a bit over 535 cubic feet of water. From the description of "Create Water" we know that "... one cubic foot of water contains roughly 8 gallons ...". So with that one spell we have ~4,281 gallons of (nearly glacier cold) water (after a bit over an hour for melting, of course). That's about half a gallon per person - not quite enough for every day usage in the city, but if there are 3-4 casters capable of this spell then the city will have enough drinking water to wait out any siege, even if their well / oasis runs dry.
For another example of a major problem in RL that is almost trivial in core D&D consider the following. All the assumptions made about how much food is produced per acreage does not take into account the idea of a local druid (or cleric with the plant domain) helping out. The third level spell "Plant Growth" has a secondary usage of "Enrichment," described below
Hmm, maybe a local cleric with Plant and Water domain is the major local religious figure? Of course, this is also a desert, so perhaps an allied (or enemical) cleric with the sun / fire domain is also present - or better yet, Sun and Earth (sand, rock, bare ground). The Plant / Water cleric focuses on praying to a deity to aid, while the Sun / Earth focuses on praying to a deity to placate. Or maybe it is a more elemental arrangement?
Water / Plant (major festival on Winter Solstice, before planting)
Earth / Animal (major festival on Spring Equinox)
Fire / Sun (major festival on Summer Solstice)
Air / Travel (major festival on Autumn Equinox, after harvest, before / as caravans leave)
Notice I changed the Water festival / blessing of the four shrines to Winter Solstice. It occurred to me that planting could begin far earlier in a desert, where the heat comes sooner than typical elsewhere, especially if water is ever plentiful. The blessing at the Spring Equinox could be as animals are being bred, or right before such, hoping for strong offspring, etc. The Fire festival would be during the hottest part of the year, in part a placation, asking the Fire based deity to be merciful, not overly burning, hold off on drought, etc. The Air festival would be in part a blessing on the caravans as they prepare to leave.
So, all in all, presuming a typically magical core D&D settlement, the settlement could - within just a few years - have strong and commendable walls of layered foot-thick stone and baked adobe earth, a nice sized oasis with absolutely massive supplies of water (Perhaps all those 'move earth' spells created a massive cavern a hundred feet or so beneath the lands just beyond the city - which was then filled with melted walls of ice to help support the weight of the ceiling, keeping it from collapsing and creating a massive year long reserve of water for the whole city in the process.), and fields capable of feeding far more than expected. After all, who's to say that the clerics or wizards living in or near the city didn't research a new spell - Improved Plant Growth (level 5 instead of level 3) that doubles the growth for each field. No, a city in a desert, if sufficiently magic, will have little trouble surviving.
All this presumes just core D&D. Once you start adding third party ideas - such as ritual magic involving multiple casters to cast spells beyond what any singular caster in the group could have accomplished at their own level of power - the situation becomes both more favorable and more complex.
Out of curiosity, how old is the city? Has it only recently grown to this size, or has it existed at this size (and location) for hundreds of years - if not longer? If it has existed for hundreds of years, then even without magic the walls could be impressive, having been built over scores of generations to hold out raiders, desert monsters, etc. The protective magic might be even more impressive. Permanent spells might have been cast every other generation or so for half a hundred generations. Wards might be in place that only need a once a year ritual to renew their strength (perhaps sapping the casting ability of those involved for a day or so as a result).
Wall of Stone can be used to create a 5 ft by 5 ft by 10 inch block (by a tenth level caster). Or, if a more square block is wished, the spell could conceivably be used to create a cube of stone ~33 inches to a side. In all likelihood, it would be better to create the 10 inch five foot slabs, buttressing them with thick walls of earth (from move earth) on either side. Move Earth may not sound like much, but recall that the walls of Babylon were not (early on) stone. They were baked earth, perhaps with some straw mixed in. All in all, given one years time, a contracted group of, say, 4-5 9th level wizards, could easily complete the job. And if the trading city is prosperous enough to have a steady population of ~8000 in a desert, it should be able to contract such a group easily.
Water is never a major issue. A casting of Wall of Ice by a seventh level wizard or sorcerer will create a cube of ice about 8.3 feet to a side. After that melts the resulting mass of water is enough to fill an volume ~8.12 feet to a side. (The ice melts automatically after 70 minutes, for a 7th level caster.) That is a bit over 535 cubic feet of water. From the description of "Create Water" we know that "... one cubic foot of water contains roughly 8 gallons ...". So with that one spell we have ~4,281 gallons of (nearly glacier cold) water (after a bit over an hour for melting, of course). That's about half a gallon per person - not quite enough for every day usage in the city, but if there are 3-4 casters capable of this spell then the city will have enough drinking water to wait out any siege, even if their well / oasis runs dry.
For another example of a major problem in RL that is almost trivial in core D&D consider the following. All the assumptions made about how much food is produced per acreage does not take into account the idea of a local druid (or cleric with the plant domain) helping out. The third level spell "Plant Growth" has a secondary usage of "Enrichment," described below
So, four castings of this - one at each of the cardinal points. In fact, I can see a cleric with the Plant domain being in demand in such a setting. Perhaps every year, just before planting, the cleric goes through a ritual on the Spring Equinox or such, praying at a small shrine at each of the cardinal points, casting Plant Growth [Enrichment]. The end result is that instead of 3 acres feeding three people, instead 3 acres feeds 4 people.srd said:
Hmm, maybe a local cleric with Plant and Water domain is the major local religious figure? Of course, this is also a desert, so perhaps an allied (or enemical) cleric with the sun / fire domain is also present - or better yet, Sun and Earth (sand, rock, bare ground). The Plant / Water cleric focuses on praying to a deity to aid, while the Sun / Earth focuses on praying to a deity to placate. Or maybe it is a more elemental arrangement?
Water / Plant (major festival on Winter Solstice, before planting)
Earth / Animal (major festival on Spring Equinox)
Fire / Sun (major festival on Summer Solstice)
Air / Travel (major festival on Autumn Equinox, after harvest, before / as caravans leave)
Notice I changed the Water festival / blessing of the four shrines to Winter Solstice. It occurred to me that planting could begin far earlier in a desert, where the heat comes sooner than typical elsewhere, especially if water is ever plentiful. The blessing at the Spring Equinox could be as animals are being bred, or right before such, hoping for strong offspring, etc. The Fire festival would be during the hottest part of the year, in part a placation, asking the Fire based deity to be merciful, not overly burning, hold off on drought, etc. The Air festival would be in part a blessing on the caravans as they prepare to leave.
So, all in all, presuming a typically magical core D&D settlement, the settlement could - within just a few years - have strong and commendable walls of layered foot-thick stone and baked adobe earth, a nice sized oasis with absolutely massive supplies of water (Perhaps all those 'move earth' spells created a massive cavern a hundred feet or so beneath the lands just beyond the city - which was then filled with melted walls of ice to help support the weight of the ceiling, keeping it from collapsing and creating a massive year long reserve of water for the whole city in the process.), and fields capable of feeding far more than expected. After all, who's to say that the clerics or wizards living in or near the city didn't research a new spell - Improved Plant Growth (level 5 instead of level 3) that doubles the growth for each field. No, a city in a desert, if sufficiently magic, will have little trouble surviving.
All this presumes just core D&D. Once you start adding third party ideas - such as ritual magic involving multiple casters to cast spells beyond what any singular caster in the group could have accomplished at their own level of power - the situation becomes both more favorable and more complex.
Out of curiosity, how old is the city? Has it only recently grown to this size, or has it existed at this size (and location) for hundreds of years - if not longer? If it has existed for hundreds of years, then even without magic the walls could be impressive, having been built over scores of generations to hold out raiders, desert monsters, etc. The protective magic might be even more impressive. Permanent spells might have been cast every other generation or so for half a hundred generations. Wards might be in place that only need a once a year ritual to renew their strength (perhaps sapping the casting ability of those involved for a day or so as a result).
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Asmor
First Post
Wow, that's a lot to mull over. I like some of your ideas, but over all I'm just not a fan of the whole idea of taking spells and extrapolating their effects into industry. It just makes the setting lose some of the magic for me.
I haven't really thought about the age of the city, but it's at its height right now. At least a few generations old, but not more than a couple hundred years or so.
My campaign doesn't have any deities at all. It's actually part of the plot... None can contact this plane. Instead, Clerics forge personal relationships with powerful outsiders (demons, angels, etc) who grant them spells.
I haven't really thought about the age of the city, but it's at its height right now. At least a few generations old, but not more than a couple hundred years or so.
My campaign doesn't have any deities at all. It's actually part of the plot... None can contact this plane. Instead, Clerics forge personal relationships with powerful outsiders (demons, angels, etc) who grant them spells.
Baron Opal
First Post
If I was the DM, I would have to argue about walls of ice providing potable water. Since the duration isn't Instantaneous I don't think anything would remain after the spell duration expires. You're solid with the walls of stone and iron, however.
Move earth is a 6th level spell, too. Still, if the oasis had 2-3 11th level wizards with an earthy focus they could have a pretty kickin' fortification after a while.
Starting to get into campaign dependant things, however.
Move earth is a 6th level spell, too. Still, if the oasis had 2-3 11th level wizards with an earthy focus they could have a pretty kickin' fortification after a while.
Starting to get into campaign dependant things, however.
Rothe said:
Nitpick, but I thought it was 12 miles. That was the figure we always used for the horizon at sea, but come to think of it, that's measured from the mast of the ship whereas typical horizon is measured from the average eye level.
Aha, the horizon. Man, I love the internet. It would be interesting to run the calculations for different sized worlds. The outer planes for example, if they aren't curved you'd be able to see a lot farther, though at -1 per 10' on a Spot check, it doesn't seem like it would matter that much.
Huh, a mile being 5280', you're at a +528 to the DC for the Spot check at one mile. For the guy in the crow's nest, to spot a ship on the horizon would be +6468 to the Spot DC. So unless the modifier for a big boat is -6448 to the DC, not too many people are going to see each other at sea.
Man, not even close to being on topic, so I'll leave it at that. Thank you, and good night.
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