Make early farming be seed-positive. Farming skill should affect yield and working speed only.
I think players expect farming to be seed-positive from the very start, at least when coming from other games. Not necessarily by much, but the amount of plants planted should be getting bigger every year, not smaller.
It just feels bad to dedicate time to setting up a farm, and have it not work at all for a long time.
The farming skill should primarily affect working speed. So if I dedicate time (full time farmer, maybe even two) to farming, it should carry me over the winter. If. Alternatives are trading, hunting, foraging, cannibalism. So there are options.
Secondarily yield per plant. That is fine too as an effect.
All this means that early on I will have maybe one farm, and a noble must dedicate most of their time to tending it. But that one farm will help me get over the winter if that is where I place my efforts.
Later as skill grows I wont need as many farmers, and they work faster so I can have more fields.
Want more difficulty? Do something else, like:
- Rats eating the seeds in storage. Someone suggested dedicated storage per resource type. Dedicated seed storage could prevent animals eating seeds.
- Animals eating your plants if you dont have fences or scarecrows
- Random weather events destroying most of a harvest (rare)
- Fertilization mechanic
- Plants needing watering (wells? water storage and transport? rainwater collecting?)
- Make plowing a field even slower
- Make seeds more expensive to buy from visitors, and have player start with less seeds