It's better to build roads that can be used by trucks.
Then, once you've created fields, you can easily transport crops, and then build more fields.
The important thing is the roads. In particular, the width of the roads and the height of the tunnels need to be such that trucks can drive through.
If you succeed in this, you'll be able to build not only fields, but also factories.
When building a factory, it's important to secure employees, so it's best to build it in an undeveloped location not too far from a city. Employees can commute by car, or, if there's a railroad, by train. Don't forget to build a large parking lot.
After many years, the area around the factory may be developed into a city.
Then, a factory can be built further away.
As for agriculture...
I'm still in the research stage, but...
I think a market is probably necessary in each region. Transporting the produce 100km to urban areas is too much work. So, naturally, farmers will either give up or start their own small-scale farms.
So, I think it would be best to set up a market in their region that would purchase their produce, and have the local market owner transport it all to the city.
In that case, farmers would only have to travel a short distance by road to transport their harvests, such as 10 kilometers. This would reduce the labor required to transport them, and would provide the impetus for large-scale farming. That's what I believe.
I am a member of the general working class. The proletariat.But...
I want to do farming...
If we use this method, it seems like it could be done in Shikoku Island on Japan.
Ofcourse, I talk to other country people. I usually write of Japanese language,
but now,this sentences is written in english language because.