NE Ridger - 12/25/2015 21:54
Norstman - 12/25/2015 21:37
NE Ridger - 12/25/2015 21:25
In the first place, I've gotten my best corn yield ever off ground that had phosphorus tests like that. Mehlich-3 phosphorus tested 8-10 ppm. 100 lbs of MAP banded in a rough 2X2. 280 bpa on 40 acres.
I'm not talking about zero applied, I'm talking about a specific situation where at least 1/2 of crop removal is being banded near the row. AND where a healthy soil microbial community is being maintained.
If the ground is being worked multiple times per year, no covers, and very little fertilizer applied, then of course the soil tests are probably going to drop and crop yields will suffer. You've wiped out the fungal networks and there's no one to sell P to the corn roots.
Those are two different situations.
So if your applying a half rate the remainder is being pulled out of the "bank" so to speak. It will deplete over time and my bet is it wont take too long. Can we agree on that? Healthy soil microbials is a whole nother deal and wasent what i was referring to in my original post or any that followed.
Plant available phosphorus
(at least for corn
) can't be discussed apart from the soil microbial community. Corn roots are terrible at picking up phosphorus on their own. "Fallow corn syndrome" is a case where the microbial community is so poor that it starves the corn for phosphorus no matter what the soil test. I've had corn nearly die from phosphorus deficiency on soil that tested nearly 100 ppm P
(lots of swine slurry on PP
).
The soil microbial community is what really determines the size of the bank. Traditionally, soil was managed for a minimal microbe community that needed lots of water soluble phosphorus in order to supply the crop needs. If the soil is managed for a healthy community that can extract mineral-bound phosphorus from the soil then your "bank" is huge. If you work the soil to death and starve the microbes, then yes, your crops can't access the bank and need artificially acidified phosphorus to survive.
If you insist on separating the two, then you're right.
strip till fertilizer savings??
