You can't, it will tell you you don't have access to this land. No, I think once you submit the contract, the field you worked on will get reset. But I haven't gone into the menu and collected the money yet. I'm on Xbox btw. The straw is still chilling in the field. "You do not have access to this land". Been there.
It offers the production of chaff at the level of 100,000l/hectare. After taking proper care of the field and fertilizing it, you can even have twice as much harvest. The amount of silage will be the same as the amount of chaff (optionally increased by 5% after using headers for a forage harvester). The optimal price of silage is about 300
Loose Pellets should be sold at standard sell points that accept loose grass/hay and straw. As for not being able to sell the Pallets of Pellets at the Pallet Sellpoint, I'd check you are not using one of the mods known to cause a conflict with the Pallet Sellpoint and break the mod. MoreBunkerSilo, PotatoWashPlant, Potato Sorter andJuWXsc.