Everybody Talks About "Picket Fence"...
Mar 14, 2009
March is the month when every farmer makes plans to plant his corn so he has a "picket fence" final stand--every stalk perfectly spaced from its neighbor. And every April I witness two shifts in that attitude.
The first comes when farmers discover the cost of prepping a planter to provide maximum accuracy. It's one thing to pay the price for keeping a 6-row planter in tip-top mechanical condition, but when modern farmers start pricing the cost of doing optimum maintenance on a 24- or 36-row planter, checkbooks get a real workout. Disk openers, gauge wheel tires, scrapers and other components need to be replaced LONG before they're actually "worn out", IF you want to optimize planter performance. Worn, maladjusted parts work just fine if you want to simply "plant corn." Picket fence stands require parts with no play, no slop, no wobble, and that means worn parts accurately adjusted and in many cases, new parts.
The second shift in attitude comes when planting season actually arrives. It looks like it's going to be another cool, wet spring in the midwest this year. Guys are going to be pushing to get the crop in, and it's going to be difficult to hold planter speeds to 5.5 mph. That's the magic speed for optimum speed spacing no matter what brand of planter you use. Guaranteed. By the 15th of May I see tractors cruising at 6, maybe 7 mph. It's always interesting to go back and check the stands in those fields, once the crops emerge.
So between the cost of making a planter mechanically perfect, and the urge to get planting done as quickly as possible, picket fence final populations quickly fall prey to simply, "get it in the ground." With that in mind, here are the things that I as a farm dealership mechanic consider the absolute minimums to getting the best stand possible, once "picket fence" has been thrown out the window:
-Vacuum meters/finger pickup-up meters: Run the units on a test stand. Test stands identify minor mechanical problems with finger units, and pinpoint proper vacuum settings for specific sizes and shapes of seeds for vacuum meters. For vacuum meters, it's critical to match each size/shape of seed you're going to plant to an optimum seed plate and vacuum setting, even if you're using those special aftermarket or OEM seed plates, knockout wheels, etc.
-Make sure residue cleaners, disk openers and row unit gauge wheels are mechanically sound. Residue cleaners should spin freely, with no bent times. Gauge wheel tires should lightly squeegee mud and debris from the sides of disk openers to create a crisp seed furrow wall--gaps between the tire and disk opener allow dirt and debris to fall into the seed furrow and compromise uniform seed depth.
-Drive chains should turn freely without jerks and kinks that jar seed units. Many "skips" in the first fields planted each year can be traced to minor kinks that developed in chains during off-season storage. Each time the kink goes around a sprocket it jars the seed unit a bit, and that impact can dislodge seeds held against seed plates on vacuum units. Eventually the chains loosen up after a couple hundred acres, and the farmer blames cold ground, wire worms or cutworms for the uneven stand in the first fields he planted.
-Finally---if at all possible, become religious about holding planter speed to 5.5 mph. That curve in the seed tube, the plastic tube that delivers seed between the metering unit and the seed furrow? It was designed for 5.5 mph. Going faster encourages seeds to tumble when they hit the seed furrow, which messes up seed spacing. Faster ground speeds also increase overall bounce and movement of the planter and its individual row units. As the row units jerk up and down, the movement can cause seeds to ricochet off the walls of the seed tubes, and every ricochet slows the seed's fall and disrupts accurate seed spacing.
In my next post I'll look at some common in-the-field planter maladies that not only destroy picket fence seed spacing, but just plain reduce final yields even before the crop has emerged from the ground.