As a farm machinery mechanic and writer, Dan brings a hands-on approach that only a pro can muster. Along with his In the Shop blog, Dan writes a column by the same name as well as the Shop Series for Farm Journal magazine. Always providing practical information, he is a master at tackling technical topics and making them easy for all of our readers to understand. He and his wife, Becky, live near Bouton, Iowa.

I've been tinkering with corn planters for more than 40 years, and can't believe how much I've learned in the past decade. The growth in my knowledge is directly related to improved technology that has allowed me to accurately monitor everything from seed spacing to how much down pressure is being applied to the gauge wheels. Here are a few things I've learned:

-Ground speed makes a huge difference. I've known for years that the curve in seed tubes is supposedly designed to optimize seed placement at around 5 mph, but a couple years ago I learned that there are situations where going from 5.5 to 5.0 mph can make a huge difference. In at least one situation, slowing down a half a mile an hour reduced the amount of bouncing the row units were doing in a rough field, and improved seed spacing by almost 5 percent.

-Row cleaners are more than trash whippers. Clearing root balls and clods away from the path followed by gauge wheels dramatically smooths the ride of row units. Accurate setting of the depth of row cleaners to match soil conditions probably justifies the cost of the new units that are adjustable from the cab. Remember the previous example I gave, of how slowing from 5.5 to 5.0 mph improved planting accuracy? We were able to get back up to 5.5 mph and maintain optimum seeding accuracy by adjusting the planter's row cleaners so they cleared a smooth path for the gauge wheels.

-Down pressure on those gauge wheels is immensely important.  Too much down pressure packs the sides of the seed furrow and inhibits root growth outside that furrow. Not enough down pressure creates crumbly furrow walls that don't maintain a nice V-shape. When seeds fall on top of crumbs or loose dirt, they end up being shallower than seeds that fell into the bottom of the V. Seed depth plays a big role in the timing of emergence, and uneven emergence has been well documented to hammer yields. As a rule of thumb, optimum yields occur when all seedlings emerge within 48 hours of each other. Any seedlings that emerge outside that window of 48 hours are essentially "weeds."