A method for dividing a field into zones with similar crop attributes and developing a mission plan for steering the harvester to selectively harvest crops based on one or more of the attributes. The attributes include protein level, starch level, oil level, sugar content, moisture level, digestible nutrient level, or any other crop characteristic of interest. The method can be applied to selectively harvest and/or segregate according to attribute any crop, including grains such as wheat, corn, or beans, fruits such as grapes, and forage crops. Directed crop sampling provides absolute value and variance information for segregated batches of harvested crop.