Seed Drill Row Spacing – Part Two (Sort of)

In my previous post on cereal row spacing I discussed the many conflicting functions of modern seeding equipment. By conflicting I am suggesting that particular functions performed by a seed drill actually work against each other. For example, optimizing the function of seed bed utilization (row spacing) conflicts with the function of minimizing seed bed disturbance. Both functions are important but designs to optimize for one function would tend to work antagonistically on the other.

These types of conflicts put rigid limitations and constraints on machine design. It narrows the range of conceptual design options available to perform the many needed functions of seeding equipment. One way to illustrate the way in which this type of conflict plays out with seeding equipment design is through the use of a Venn diagram. With a Venn diagram, we let a circle define the “space” of design options to impart a specified function in a seed drill. Each function which the drill needs to perform as a condition of commercial acceptability is then represented by a separate circle.

The figure below shows a Venn diagram for seven distinct functions which I believe a modern seed drill needs to carry out in order to succeed in the marketplace. While there are no doubt many more functions not considered here it is sufficient to demonstrate the challenge and complexity involved in equipment design.


The figure shows how these functional conflicts work against each other and severely limits the alternatives for engineers and equipment designers. The small shape which I have outlined in black shows the small overlapping area of “solution space” which can reconcile all of the mostly conflicting and non-overlapping space of design alternatives. Note that the optimal design solution for each individual function does not necessarily lie within the small overlapping “solution space”. However to obtain greatest commercial value – which is in theory the maximized sum of values of the seven functions – the ultimate design must lie within the small space.


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