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| I'm seeing conflicting opinions on soybean population in Iowa.
Dr. Palle Pedersen (who just moved from ISU to Syngenta) has been calling for lower populations, planting as low as 125K hoping for 85K stand. Says that's most profitable. And those beans should be planted in cold ground after treatment with a fungicide. The earlier the better.
Dr. Tracy Blackmer, the Iowa Soybean Association guru, has recently put out data that shows a greater yield with a greater population, more like the 160K that has been traditional in Iowa in 30" rows. What I saw in his rawdata was that indeed the greater population did give more yield, as much as TWO bushels. With seed at $50 or 60 a sack, planting 40K more costs more than the value of 2 bushels at harvest.
The trouble I see with low populations is crusting. Made worse by splitting the seed into 15" rows. It takes 8 or more seed to the foot sometimes to shove up a hunk of crust to break through without breaking the plants. Too low a population can have poor emergence with a crust. And we often get a crust from rain that fell the day after planting. Just because we worked the ground to make a slot to put the seed in, or worked the ground by traditional full till methods, there can be lots of fines to make that crust. And then it stays too wet to make a 3rd day pass with a rotary hoe to break the crust (that won't break by the hoe because its too wet). Loosing stand by the foot because of crust doesn't make for a great yield either.
In 2008 I was going to plant 140K early with cruzer-max. No till. Soil didn't reach 60F until mid June. That's not early and the 90% germ (and some 85%) didn't come with the cruzer-max because it was too fragile to have a workable germination after rattling through the treatment machine. Indeed I didn't have to look hard to find splits and loose hulls even though I handled the seed very gently and didn't stir in the graphite and innoculant. So I planted the 90% germ at 160K and the 85% at 178K. The the mid July fill ins, I planted with two passes of the 30" planter still set for 178K. They made buckshot that dried by November because those late beans were very short maturity. I made 47 bushels, my goal was 70. My new tenant is prepared for his second year on my farm doing continuous corn with strip till.
Gerald J. | |
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Split Row Planter Population
