I do not like to work with grids unless the application software requires it.  I don't have square fields and fields don't have square grids in them.  I contour the yield data and then create the application maps based on those contours.  I will agree that the application equipment can not precisely follow the contour lines, but I think the resulting maps are a better representation of the field. 

• I filter the yield data carefully.
• Then I create the contour lines.
• At that point I apply the removal formula to the data.

I am not saying that may method is any more correct than any one else, but I am happy with my process.  I attached this image on the Crop Talk thread, but I will add it over here also.

(CropRemovalRX.jpg)

CropRemovalRX.jpg (60KB - 131 downloads)