Results and Discussion

Conversion is based on a pound per acre basis. If the soil test result is reported in ppm, values must be converted to pounds per acre. For phosphorus, 2 conversion equations were generated since the conversion factor between Mehlich 1 and 3 for soils with pH <6 was different than for soils with a pH >6. To convert Mehlich 3 P to Mehlich 1 P, for soils with < pH 6.0, divide Mehlich 3 P by 1.97 and for soils with pH >= 6.0, divide Mehlich 3 P by 1.52. It is important to pay close attention to soil pH which will determine your soil test level and recommended fertilizer application rate. The newly generated soil test calibrations for Mehlich 3 Extractable Phosphorus and Potassium in West Tennessee are shown in table 2 and 3. To convert Mehlich 3 K to Mehlich 1 K, subtract 27 from Mehlich 3 K, then divide the resultant value by 1.53. There was a substantial difference between the previous and newly generated conversion equations for potassium for West Tennessee soils. For example: A Mehlich 3K soil test value of 150 pounds per acre will fall within the medium soil test level using previous conversion equation (Table 1) but will be in the low soil test level with the new conversion equations (Table 2 or 3).