Soybeans left on the ground come straight from the bottom line.

You wrestle with the weather all season long, and the vagaries of Mother Nature don't let up at harvest time. The risk of lost grain due to lodging and adverse weather increases as the season progresses, too.

On average, harvest losses run about 6 bushels per acre for corn and 3 bushels per acre for soybeans. But that doesn't have to be the case. Top combine operators cut these losses by 75 percent or more, leaving only 1.5 bushels of corn or less than a bushel of soybeans per acre. That increases crop returns by $10 or so per acreÑmore than enough to pay for the fuel to harvest the crop.

In most cases, not much of that loss occurs in the threshing machinery of a combine. Most operators routinely fine-tune concave clearances, cylinder (or rotor) speed, fan speed and sieves. The majority of harvesting loss happens at the front end of the machine.

"That's especially true of soybeans," said Bill Casady, University of Missouri-Columbia (UMC) agricultural engineer and member of the UMC Crops Focus Team. "Gathering losses at the header account for nearly 90 percent of soybean harvest losses. Good combine operators keep their headers in good mechanical shape and make adjustments based on the condition of the crop."

Start by reading the operator's manual and look for specific information for your particular header. Casady offers a few tips in general to get you started:

Adjust the pickup reel to gather as much of the crop as possible. The reel axle should be positioned about 8 inches ahead of the cutter bar. Adjust chains and belts. Adjust the reel speed to 1.5 times ground speed, using the following formula:

Reel speed (rpm) = combine speed (mph) x 504 divided by reel diameter in inches.

Example:

Ground speed  =  3 mph

Reel diameter  =  42 inches

Reel speed = 3 x 504 / 42 = 36 rpm

A reel that turns too fast will cause shattering; one that turns too slowly will drop stalks.

Use a well-maintained flexible "floating" cutter bar to get as many of those low-growing pods as possible. Knife sections and ledger plates should be clean and sharp. Adjust wear plates, hold-down clips and guards.

Don't get in such a harvest time hurry that you sacrifice safety, Casady cautioned.

"Always shut down the combine and turn off the engine before making any adjustments or unclogging a plugged header," he said. "We all know a few people who can count on one hand (the one that's left) the number of times they got by with unplugging a moving header."