Shaun Casteel is adamant that many farmers are planting more soybean seed than they need to today with the equipment they're using and today's varieties. He's working with Extension educators to set up trials on farms across the state to demonstrate and verify that soybeans will produce top yields at populations once considered by many as too thin to leave without replanting.
"We're recommending 100,000 to 120,000 plants per acre in any row width," he says. The new recommendation will show up in the 2012 version of the ever popular Purdue University Corn & Soybean Field Guide. This pocket reference is produced by Corey Gerber, head of the Purdue Diagnostic Training Center.
Casteel is careful to distinguish between recommended plant populations and seeding rates. To get to the desired rate, you may need to plant 130-150,000 seeds per acre, for example, depending upon your soils, type of equipment used and conditions at planting.
One issue cropping up is that some people are comfortable just leaving their planter set where it is. If they've been planting 185,000 seeds per acre in twin rows all the time, trying lower rates may mean adjusting the planter, depending upon the make and model. It could mean needing to change sprockets. And it may also mean recalibrating the seed monitor.
These steps aren't insurmountable- they just take time. Depending upon the planter, they may not take long at all. It's often just a matter of a few minutes needed to switch sprockets on some planters.
The bigger problem is keeping everything straight as you make the switch. Some planters have what they call half-rate and full-rate settings. How sprockets that power drive chains are positioned determine if you're on half rate or full-rate.
Let's suppose you decide to give Casteel's recommendation a try. You were the guy at 185,000 seeds per acre. To get to 140,000, you need to go to the half-rate setting sprocket to get the planter to drop such a low rate. That means changing sprockets and making other adjustments.
Three things could happen here and only one is a god thing — kind of like the football coach who runs the ball because if he passes, two of the three outcomes are bad — there could be a dropped pass or interception. He's forgot about that a run could result in a fumble- sometimes even old football coaches must learn to step outside their comfort zone.
The good scenario is that you find the directions in the dusty planter book, make the change, and set it correctly. You drop around 140,000 seeds per acre. With your planter, the closest you can get may be 145,000 or 135,000. Choose the rate you're most comfortable with trying.
The problem scenarios are (1) you wind up doubling it by mistake and now you're planting 290,000 seeds per acre, or you slip the other way and you only plant half of where you were, or about 90,000 seeds per acre. That won't be enough.
In the end, Casteel hopes farmers who haven't already considered dropping rates will try it, and take the time and patience to read their planter manual and achieve the proper rate.