My 2c.
First, I agree that farming should be more demanding. Also, I'd like to see some differences in it.
First, the start up farming problem. IMO this might be easiest to solve, by creating a new type of plant (we likely would like more plants anyway), maybe called cave moss or something.
It should, basicly be plump helmet made easier. It wouldn't even require soil, just some damp stones. It would grow without much problem or attendance of farmer, could be harvested easily, and turned into some really poor quality booze. Ideally, you could have one farmer design a large field, to get food so you won't starve, and will get some booze. Neither the food or booze is good, but you will suvive.
This plant should have longer growth time, so later on if you have more manpower, fertilizers and irrigation, other plants come more feasible.
This would solve the problem with farms in the beginning. You could still farm, just don't expect much else then survival.
When farming advances, I'd like to see seasonal farming and underground farming pretty much ignored. Instead, plants would have requirements on temperature (min-max), moisture (again, min to max), soil richness ( likely only min, can plants die from too much nutrients?) and light requirements (maybe on scale light, shady, dark). This way, arctic fortress might grow during summer what temperate fortress grows during winter. If it is too cold or too hot, nothing grows. Light would limit some growth. Some plants require open skies, others might do well under a cliff, but still outside, while some only grow in darkness. Each plant should drain moisture and nutrients from ground (maybesome could have negative drains, to return one or the other to soil. I think peas are one example of plants returning nutrients, but am not sure)
For farms, maybe we could abstract the whole farm area?
We could still build farm plots in different sizes like now, but it would only be one farm. Farm would have max worker amount, ranging from 1 worker up depending on the size. This would mean how many farmers could work on the farm at the same time.
Farmers work would also change. They would get "work on farm" assignment, meaning they would walk to the farm, and then start some of the works that need to be done.
Different farm work could include getting water (to keep the water level proper), using fertilizer (to add soil richness), getting rid of weeds (which would take space, water and nutrients from real plants, and hamper growth if not limited), deal with pests (maybe have some small animal traps, etc.), plowing the fields (after harvest and before replanting), and of course harvesting and planting. Fields would require set amount of seeds (maybe one per tile, maybe less) that would be used in planting. When the harvesting would be done, the farmers would gather the harvest on the side of the farm. All tiles would be harvested, and the resulting food would be plased in sets of 5 (so, say farm produces 13 food in 10 tiles, instead of 10 single piles you would get two piles of 5, and one poile of 3).
This would pretty much keep the producion suitable with rest of the system.
However, if the whole farm area is considered as single entity, then it is easier to implement partial productivity. I think one of the reasons in current food problem is that food always produces 1 unit, which in itself is pretty much food. This could be fixed by multiplying everything with larger numbers (like planting 100 seeds in tile, and gaining 100-500 plumphelmets), but that will only get us more problems.
Or we could have single farm entity, for example 5x5.
When you plant the seeds, there is 25 seeds(assuming this won't change). Then, you can work on farm. Small gains could add the yield to 26 or 27 plants, and poor work could drop the yield to 10 or less, but you sould still get something. By making the farm a larger unit, we can have smaller increases and decreases to the yield. This allows the low productivity in beginning, or with poor conditions, and good productivity in the end.
It would also make it easier to limit over production.
For example, say the x seeds are originally planted.
Behind the scenes the farm would gain and lose growth points. Say, for every day there is adequate water and nutrients, +1x growth points. For everyday vermins are loose on farm, -5 growth point/vermin. Daily growth points are multiplied by 1-% of weeds present.
So you start with x seeds, and during the time you get the certain amoiung of growth points. Then it is harvest time.
For 0-100 growth points, you might get X times 0.1 plants.
So for each ten seeds, you get one plant. Rounded normally.
800-1200 growth points might give you X times 1 plants.
1200-1600 could give X times 1.2 plants.
1600-3000 could give X times 1.5 plants.
3000-6000 could give X times 1.8 plants
and so on.
This way, you could make it harder to get the real big crops, because to get really big pultipliers, you would really need to work hard. Of course, some plants should be easier to grow then others, so they could have a fixed or multiplier values to growth points.
The farm could also have a shed, which could store seeds, buckets, tools, fertilizer etc as a stockpile. This would reduce teh running around of the dwarfs, as the farmers could take the items from the shed.
So, any comments or questions? I know I'm only a dabbling explainer, so this could need some clarification.