I see farmers in Hermiston topping their corn fields. It looks like they chop off the top 2 feet or so. Does this make corn ripen faster or increase the size of the ears or just decrease the amount of roughage going through the combine or something else?
The topping of plants is for seed corn production.
The tassels (where pollen is produced) are removed so that plants can only be pollinated by other plants. The rows that are topped are female rows, and the rows that are not topped are male rows.
This is the process of hybrid seed. Hybrid seed results in much better plant vigor and yield. Hybrid corn seed was first developed in the 1930's.