Magnesium Recommendations

Look in the left hand column and find the soil test Mg level in ppm as reported on the bar chart in the middle of the soil test report then go across to the appropriate "Optimum Mg" column for that crop to determine the amount of Mg recommended.

Because of potential animal health problems due to an imbalance between potassium (K) and Mg, a higher Mg recommendation is made for some crops when the soil K level is greater than 200 ppm. The need for this adjustment is noted on the appropriate crop sheets in this manual. For crops where this adjustment applies, when the K soil test level as reported on the bar chart in the middle of the soil test report is above 200 ppm, then use the far right hand column in this table to determine the Mg recommendation.

Since the most common source of Mg is magnesium containing limestone, the Mg recommendation is also given on the soil test report as the percent Mg required in the recommended limestone to meet the Mg requirement. To calculate this percentage divide the Mg recommendation determined from this table by the limestone recommendation determined from table 1 and multiply by 100.

Recommendations are given as elemental Mg because limestone is required by PA law to be labeled with the elemental Mg analysis. You can convert the the Mg recommendation to MgO by multiplying the Mg recommendation times 1.6.