Banished 1.07 + MM8.01, no other mods (ever), fresh game
My 11x11 cotton plantations (tried normal "crop" as well) are yielding about 65 per season. My tobacco plantations are closer to the expected norms (700 last season)
My farmers are 5-star happy, educated, using steel tools, live right next to the plantation with a barn.
This isn't just one cotton plantation, it's all of them. I've tried resting them for a year, deleting/recreating them, adding a second farmer, enabling/disabling "pickup" - no changes always about 65ish
<a class="ipsAttachLink ipsAttachLink_image" href="<fileStore.core_Attachment>/monthly_2018_09/mm_cotton.png.a8d5e9469b29a4dc964a528a83825ff2.png" data-fileid="3118">[img]<fileStore.core_Attachment>/monthly_2018_09/mm_cotton.thumb.png.0b1542024d4dfe9e8d77309de8bd1534.png[/img]</a>
