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EC Nebraska |
As to the phosphorus, I'm skeptical on the infurrow stuff. It's not likely to pay for itself, unless corn goes back to $6. I like 10-34-0 or MAP banded 2X2. The best yielding corn I ever raised (280 bpa field average) was on soil that tested 5 to 8 ppm phosphorus. I had banded 100 lbs/acre MAP in a rough 2x2 that spring. Banding phos on your high pH soil is going to pay, but it needs to be 40-60 units of phos, not the little bit that 3-18-18 would give you.
For the pH, you can't lower it economically. You can manage it, that's all. I'd be more concerned about some of the low pH areas. Some of them have a lot of hydrogen on the CEC. If you could VR 2 ton of calcitice lime on where the hydrogen base saturation is above 15, that would improve them a lot. (if you've got the VR machine out there, may as well put 1 ton of lime where the hydrogen is 10-15)
100 lbs AMS ahead of corn is not going to affect the soil very much. It's all getting used by the corn and if you are a corn/bean rotation with no sulfur for the beans then you're really in a sulfur deficient situation. On those higher pH clays, I'd topdress 150-200 lbs AMS as soon as reasonable after planting. (or just before if you can't get it done by V3). That will acidify the top few inches of soil for a couple months, and free up some phosphorus when the corn needs it. If you get the lower pH areas VR'd with the limestone, go ahead and put the high rate of AMS everywhere.
When are you applying your K? I like that topdressed as well. I've got eroded clay hillsides that test similar to your high pH clays, and last year I started topdressing 200 lbs AMS/50 lbs KCl on the corn and 50 lbs AMS/100lbs KCl on the beans. The crops on those hillsides look fabulous with that treatment, and they seem to have a lot better drought tolerance as well. In season K applications let the crops have a chance at it before the clays and calcium can tie it up.
Just a few thoughts to consider. Remember, I farm a couple hundred miles away from your area, and free advice is what you paid for it.
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soil analysis for p,k
