# Large mobile farms?

In my world agriculture doesn't work, the day lasts many years so the people are always on the move. You can't farm if you won't be there for the next 8 or 9 years. Well, When I read this question it got me thinking. After reading this question, it made me wonder, would an airship be able to carry a small plot of farm land?

The plot could be any size. And medieval as well as modern and future situations could have this. The largest Medieval villages would only contain at most 200 people. Modern towns would have more around 700-900. Future cities would contain up to 40,000

• What did the people eat before they started flying around? Why can't they settle for a year at a time and grow food then move on ahead the the terminator? Aug 12, 2015 at 20:26
• They ate animals, But large civilizations require agriculture. They're not like us in their head set. They would feel uncomfortable being in the same place too long. Kind of the opposite of homesick. Aug 12, 2015 at 20:28
• I'm going to be gone for most likely the rest of the day so I can't answer any questions for a while Aug 12, 2015 at 20:35
• I'm going to have to suggest my same boring answer again, just put them all on boats. it's far easier to meet their food needs this way, boats float much more efficiently then zeppelins. besides, the only way for your people to be migratory that I can think of would require a water world Aug 12, 2015 at 21:53
• In my world the majority of the world is land(61%) So they wouldn't realistically use boats. Imagine if the map was inverted. all landmasses were oceans and all oceans are continents. Aug 12, 2015 at 22:01

Density of loose earth = 1200 kg/m3

Weight a large, modern day zepplin can carry = 226,796 kg

Farmland required to feed 1 american = 1 acre (4046.86 m2)

1 acre of loose soil weighs 4046.86 m2 * 0.5 m * 1200 kg/m3 = 2,428,116 kg

Some really rough numbers to give a first guess... but a modern day large zeppelin apparently can't even come close to holding the mass required to hold enough farmland to feed even a single person (assuming a 50 cm soil depth).

We can make some assumptions to help the case like eating a vegetarian diet requires less land, using hydrogen like you suggest, as opposed to helium in the example I gave... but these are pretty small improvements compared to the order of magnitude weight difference that needs to be addressed.

• I should point out that the square-cube law works in the zeppelin's favor here. Carrying capacity grows at an cubic rate, while weight of ground only grows at a square rate. Thus a REALLY large zeppelin could theoretically manage a much better ratio of carrying capacity to land. Plus you could grow food with far less weight using hydroponic approaches. Still, I think it wouldn't be enough to fit any decent size of people on your zeppelin, even if you did scale it up. Aug 12, 2015 at 21:47
• Also this assumes we use square meters. But if I were to use square feet, well then that's another story there isn't it? Aug 13, 2015 at 18:30

I would suspect that as long as the people are not staying to close to the morning side that they will be doing a LOT of gathering of plants and vegetables along the way. Plants will likely have to die or go dormant when they get past evening, and wake up in the morning and grow and reproduce. Long days make a huge difference in the growing capabilities of plants. Look at Alaska, their growing days can be 18+ hours long in places. They get huge produce and lots of it, in a relatively short time.

So it would also be possible for the city to float 'ahead' park and grow some crops for a few months, harvest and then leap frog ahead to another useful place to grow the next batch.

while some plants could be grown on the ship, it would likely mostly have to be a few fresh fruits and veggies to help supplement the traveling diet. Dirt is heavy and so are plants, they need a lot of water too. I think gathering food from the local plants below and or leap frogging to raise their own crops would be more likely.

• To the first part, plants do neither, instead they wilt away leaving seeds that are similar to Brazil nuts or coconuts. And to the second part, who would tend to the crops, who would keep animals away from it and most blatantly The amount of co ordination from that makes no sense, The people who plants the crops get nothing and the people who harvest get everything. Aug 12, 2015 at 20:32
• @majornorwal that is not what I meant. migrate forward a ways toward 'noon', you set down, plant crops, and wait a few months, then harvest things later toward evening. Then move toward noon again to start over. Aug 12, 2015 at 20:36
• @samuel suggested the same thing, the reason it wouldn't work is because they're brain is wired differently than ours. The would be feeling depression and nausea. Basically the opposite of homesickness Aug 12, 2015 at 21:33