Farmers often decide independently when and how much area to plant each crop. As farmers unknow the demand for crops, they tend to plant the most profitable crops from the previous year. If all farmers reproduced this behavior, they would overproduce the most profitable crops and underproduce the least profitable ones, leading to a supply-demand imbalance and price fluctuations. To solve this problem while maintaining farmers independence, a collaborative optimization-based tool is proposed that allows to centrally define the minimum and maximum proportion of area to be planted with each crop and in each period to be sustainable in terms of profits, waste, and unmet demand, and to use this proportions to independently define the planning of planting, harvesting and crop distribution for each farmer. The proposed tool is assessed by determining and comparing what the supply chain outcomes would be if farmers used the collaborative tool or not.