74 Row Units - Low Soybean Population - Skips?

Let me start by saying this is my first time trying to work with AC row units, and plate-type planters in general. I'm fairly used to newer-ish finger pickup and vac planters. Bear with me on this long post. It's going to be the 4th of July and I'm still trying to get soybeans in after 15" of rain over the last month... And I've never planted beans before, all the equipment is new to me, so there's a lot of learning going on. Maybe this thread will end up helping someone else in the future, too.

Edited by wjohn - 03 Jul 2026 at 10:40pm

Tenn allis wrote: Don’t think the rolling knocker is your problem all it does is push seeds out of the plate that maybe a little snug Put a small amount of seed in each box and run it for a little or turn it by hand then easily lift it off and turn it upside down undo the plate so you can see the seed plate and see if any seed are hung it if there’s none hung in the plate then the rolling knocker is doing its job We’d always check our planter on some gravel road or another hard surface pull it slow then go back and measure the distance between the seed to check our population Looks as if you run the original Allis plate you’d get a higher population

WJohn, more than likely your planting travel speed is too fast for for the planter’s chain drive sprocket(s) setting?
In theory, when seed plate is slowly rotated(your hand rotating drive tire test ~ 1/2 mph?), the seed has more time to fall into plate cell, more time to singulate, & more time to drop to seed trend, etc…?
In actuality, you drive 4-5-6mph & planter grossly loses time for all events to happen.
Seed size & seed lubricants (graphite/talc) can affect actual population numbers too! More than one would think.

Not changing seed size or adding seed lubricant, just keep playing with your drive tire sprocket(s) until satisfied.

Edited by AC7060IL - 04 Jul 2026 at 8:46am

Tenn allis wrote: It’s been several years since we ran a 74 unit but are you going by the book value for population if I remember correctly the book value is either half the actual rate or maybe double it’s been so many years since we ran a 333 planter maybe someone on here that has worked with them more recently can chime in or maybe it’s the sprocket tooth count I just don’t remember sorry I can’t be of more help Those units are pretty much bullet proof once you get the right combination of sprockets and the right plate and around 5 mph is a good speed

Curious? You said, “it’s planting half of what it should be.”
20” rows right? What seed spacing is it actually planting?
Reason I ask is 70,000 seeds per acre can sometimes be adequate, given a weed free field &/or drought conditions?

Book value in pounds is how it was done. It was a "controlled spill" similar to JD 7000 bean cups. Singulation isn't going to happen.

Ky.Allis wrote: Assuming they are press wheel driven row units, check sprocket tooth count on driving & driven sprockets. Regular chain or extended pitch chain or flat link chain. I remember back when I used 78 row units, the chain was extended pitch, but the sprockets were for regular chain. Made it somewhat confusing picking correct number of teeth for sprockets required.

wjohn wrote: AC7060IL wrote: Curious? You said, “it’s planting half of what it should be.” 20” rows right? What seed spacing is it actually planting? Reason I ask is 70,000 seeds per acre can sometimes be adequate, given a weed free field &/or drought conditions? It's giving me about 3 seeds/foot in the field. Of course there are pretty big gaps depending on how well it drops. Going off of KSU recommendations and neighbors, everyone says I want to be over double that for around here (hot, dry, planting late in season, etc.). I think 70K would work if I were further north. Although with all of the rain this year, who knows.

So a quick/simple population math.
43,560sq ft is one acre.
Divide 43560 by 1000 to reduce numbers for ease = 43.56sq ft(1000th of acre).
Divide 20” row space by 12”/ft = 1.67 ft.
Divide 43,56 by 1.67 = 26ft. REMEMBER 26! So every row’s 26ft is a 1000th of an acre.
Now multiply the # of seeds planter drops per ft x 26ft ( 3 seeds x 26’ = 78). That’s one-1000th.
So Take 78 x 1000 = 78,000 seeds/acre.
If germ is 90%, then 78,000 x 0.9 = 70,200. That could be fine?
No disrespect to KSU, but have they ever tested your farm, your soils, your climate, your seeds, your planter, your agronomics, any of your current situations,,, etc??? Agronomic mindsets are kinda like setting planter seed spacings, take it as a ballpark figure then play/deviate to your farm’s satisfaction.
Soybeans can/will compensate. If there’s extra space, water, sun, soil nutrients,,, they are “kings at compensation.” Probably biggest challenges for them is weeds & deer (wildlife feedings). Seems we’re all over planting for the d@m deer!!

I got out and tried with the original AC plates... they were very, very close to matching my hand spin test in the air. I'm putting down the right number of seeds/row feet to get my target population.

tbran, thanks for chiming in with your decades of experience. You have used the Lincoln B-SOY 3X plate with success? Or have you been using the B-SOY2 (if you happen to remember)? My beans are 2250 seeds/lb. Usually 3-4 fit in the B-SOY 3X cells

Tbone95 wrote: Again, sorry for what might be an invalid comparison, but in my JD 7000 book, you set population by a combination of sprockets and weight per 100 beans and my plate cells were very large like the ones you’re calling original. Drive along a hard surface and dial it in by checking drop rate per distance. Usually either good or one tweak. So small beans, big beans, there was information for anything I ever bought.

tbran wrote: i MAY BE WRONG, but your hopper bottoms look like they have the stainless steel wear ring. this means the latest style - I don't know what units they were originally on - only the first have the cast iron cap. Every thing from the 72 units have the pastic cap with setscrew. Sorry for the omission of identification. I will have to go ot the farm and look - seems my plates were white? - I had better go look.

Tbone95 wrote: 190 k is sure a lot, but you didn’t hurt anything other than your seed bill. The first time we planted beans, dad got all confused in the manual. I just started planting, he said it was all set. I drove a while, thought dang, looks like I need seed already. Remember, first time ever planting soybeans. So I topped off seed, went a while, needed seed! What the heck? Got the manual, started looking, saw how dad set it up. I started asking questions….got his number, and I said, then what? Times 4 because a 4 row planter? He says yes! I said um…..doesn’t work like that! Thank god at the time I only had a 4 row planter and it was a six acre field!!!   We put down close to 400000 as I recall, about maxed out the sprocket ratios. They turned out ok. About average yield. Just LOTS of seed per acre used!