  A method for harvest planning based on the coupling of crop assignment with
vehicle routing is presented. Given a setting with multiple fields, a path
network connecting these, multiple depots at which a number of harvesters are
initially located, the main question addressed is: Which crop out of a set of
different crops to assign to each field when accounting for the given setting?
It must be answered by every farm manager at the beginning of every work-cycle
starting with plant seeding and ending with harvesting. Rather than solving an
assignment problem only, it is here also accounted for the connectivity between
fields. In practice, fields are often located distant apart. Traveling costs of
machinery and limited harvesting windows demand optimised operation and route
planning. Therefore, the proposed method outputs crop assignments to fields and
simultaneously determines crop-tours, i.e., optimised sequences in which to
service fields of the same crop during harvest. It is of particular relevance
for larger farms and groups of farms that collaborate and share machinery.
Integer programming based exact algorithms are derived. For large numbers of
fields, where these algorithms may not be tractable due to computational
constraints, elements of clustering and the solution of local Traveling
Salesman Problems are added, thereby on the one hand rendering the method
heuristic and in general suboptimal, but on the other hand maintaining
large-scale applicability.
