Question, does anyone know what happens with a Forestry multifarm when you have two crop sections, one planted with barley and one with wheat? Does it replant with barley and wheat specifically or does it just indiscriminately use what seeds it can get?
Depends on how you have it managed. If you have it set to "automatic" then it will only plant what is set in the circuit board. If you set it to "Managed" and put the Wheat electron tube (I think it's iron, but I don't remember) in one side and the Barley, if there is one, in the other and plant the items yourself, then it should be fine.
If it works with barley, then it will keep them separate. I don't know if it does, though. Golems can't harvest barley for instance. DW20 mentioned "IPlantable" in the latest FC2 SMP, so maybe barley isn't set up correctly for cross-mod interaction.
You guys misunderstand how multifarms work.
The key thing to look out for is whether your farm is "managed" or "manual". You can have crop and vegetable farms in both modes.
A "managed" (automatic) farm will lay down soil, plant seeds
from the first slot in its seed inventory that holds any valid seed, wait for plants to grow, harvest them and plant something new in that slot, again
from the first slot in its seed inventory that holds any valid seed.
A "manual" farm, on the other hand, does not lay down soil and does not plant anything. It expects the player to do that. However, once something the player planted has grown, the farm will harvest it and then
replant that exact thing in that exact location, provided it has a matching seed anywhere in its seed inventory.
So for a farm that keeps multiple plant types, you want a "manual" farm. If barley is harvestable by the multifarm at all, it probably needs a crop farm (bronze tube), but if it doesn't work, try testing with a vegetable farm (iron tube). Harvestcraft has some confusion as to what of its many dozen plants can be harvested by what farm type, for example; maybe Natura falls into the same trap.
After configuring your circuit board, manually place your dirt and irrigation water, hoe the dirt into farmland, and plant whatever crops you wish in whatever pattern you wish. Then make sure the multifarm has a few seeds of each crop type in its seed inventory (yes, this does limit you to at most six different crops on one multifarm, but you will probably struggle to reach it unless you run Harvestcraft). After that, you can leave it alone and, as long as the crop is actually harvestable, it will happily work all the different crop types you gave it in exactly the ratio you pre-planted.