Understanding Critical Soil-Test Levels for Phosphorus and Potassium
Tri-Ag • October 15, 2026

Once your pH is where it needs to be, there’s another question worth asking:


Where are your phosphorus and potassium levels?


When soil-test levels are below critical, the probability of a crop response to added fertilizer is greater. As those levels increase beyond critical, the probability of an economic response generally decreases.


That’s why your fertility plan shouldn’t begin with, “What did I apply last year?”


It should begin with, “What does this acre actually need?”


Use this fall’s soil tests and yield data to identify where your fertility dollars have the greatest opportunity to generate a return.


Get the pH right. Know your critical levels. Invest where it matters.


Talk with your Tri-Ag agronomist about building your 2028 fertility plan.


#TriAg #SoilFertility #Phosphorus #Potassium #SoilTesting #Agronomy #OhioAg

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