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EC Nebraska | Well, here's my thoughts. You're removing what, 50-60 lbs P with a 160 bpa corn crop? 5 gallons 10-34-0 supplies less than 20 lbs. So you're getting another 30-40 lbs from somewhere, probably your MAP applications. Your MAP application is 50 lbs P? So if that's all the phos your putting on, then check my math. 55lb average removal. 5 gallons 10-34-0 supplies, say, 14 lbs. (some of that ties up too) 55-14 = 41. That 41 lbs is probably coming from past and current MAP applications. 41/50 = 82%. Looks to me like you eventually recover about 80% or so of your applied MAP. Probably that's a paying proposition. Seems like banding AVAIL treated MAP could be worth it. Jumpstart seed treatment did easily pay for itself on my high pH, low phos soils. That's here.
Sulfur is an interesting situation. Tile ran a month in the spring this year, probably they often run longer than that? That would seem like enough leaching to move the free sulfates from the soil solution. So maybe the rest of your sulfur is tied up in organic matter, only frees up through mineralization? Are your soils generally fairly cool late into the spring? Would there be much mineralization till mid summer? You might benefit from top-dressed AMS the same way I do. It supplies free sulfate in the soil solution early in the crop growth stages when very little is available from the soil. And young corn really likes NH4. I apply 100-150lbs AMS between V1 and V5 broadcast on the corn. It improves color and consistency and kicks plant growth into high. Gets more leaf area available to capture sunlight sooner.
My $.02 worth. | |
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Phosphorus in High PH soils
