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Brooks, MN | I started variable rating last year. I made the decision to not apply MAP on some zones above a high threshold. In Climate FieldView I could see right to the line the zones that had no MAP applied. My zones last year were larger and square shaped on this one particular field, so it was very easy to see the defined line and it affected the entire zone. We also had a very wet spring, and I had to top-dress nitrogen later, so it's possible that the relatively small about of ammonium in the MAP was the difference between the zones as it may have hung around longer. I can't say for certain, but we've made the decision to always apply a minimum of 50lbs of MAP regardless of soil test level as a "starter" broadcast.
I'm not saying that I'm right to have made the change, I really don't know, but I think I've limited my downside. What I have learned is that usually it's best to try things out. If I were you, I'd recommend putting in a check strip if you can. Just see for yourself what works in your situation. | |
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Is a Low rate MAP (phos) app worth it on good soil test farms?
