How many pigs can I keep on a hectare?

Question:
How many pigs can be kept on 1 hectare?

Answer:

Just about anything is possible - and how long is a piece of rope?
In the East, they farm with pigs, ducks and carp in the same building.
Pigs on the top floor, ducks among them and the carp in the water at the bottom.

The normal recommendation is 20 hectares for a 100 sow unit.
It is not clear what type of pig farming is intended - intensive indoors or
extensively outside or something in between.
Outdoors need more space. The problem is not only the number of sows being kept, but also the growth margins that will hopefully appear with successful breeding.
A sow should be able to grow at least 20 pigs a year - ten times 2.2 litters per year
(in a 100 sow unit there are always 1000 plus pigs on the farm). All these pigs
produce mites and urine plus the cleaning water that has to go somewhere. Sewage dams should preferably be away from the buildings and one hectare is not very large.