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Fertilizer Recommendation Tables - 2008 Revision

Author: Keith Reid - Soil Fertility Specialist/OMAFRA
Creation Date: October 2007
Last Reviewed: November 2008
2008 Revision

Magnesium Soil Test Ratings and Interpretations for All Crops

Soil Magnesium (1 M ammonium acetate) mg L-1 of soil (ppm Mg) Rating Recommendation
Below 20 HR If lime is required, use dolomitic. Magnesium should be applied for all crops. If pH is below 6.5 apply dolomitic lime. At higher pH values apply 30 kg soluble magnesium (Mg) per hectare. Potash applications in excess of those recommended by soil test will increase the probability of Mg deficiency.
20-30 HR Magnesium is required for tobacco, or if potassium soil test is above 250. If pH is below 6.5 apply dolomitic lime. At higher pH values apply 30 kg soluble magnesium (Mg) per hectare. Potash applications in excess of those recommended by soil test will increase the probability of magnesium deficiency.
31-39 MR If lime is required use dolomitic. Magnesium to be recommended if potassium soil test is above 250. Potash applications in excess of those recommended by soil test will increase the probability of magnesium deficiency.
40-100 MR If lime is required use dolomitic.

100+

 RR

If lime is required either dolomitic or calcitic may be used.

HR, MR, LR, RR, and NR denote, respectively, high, medium, low, rare and no probabilities of profitable crop response to applied nutrient.

Approved: Ontario Soil Management Research and Services Committee (June 2008).

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