Knowing What Is In Your Soil Can Save You Money

Use of soil test results for phosphorous and potassium combined with nutrient recommendations for the specific crop as the basis to determine the amount of fertilizer for a field can have a significant financial impact.
Consider the following two scenarios...

Scenario 1: Phosphorous

Assume there are three 50 acre fields in corn with different soil phosphorous (P) levels, and the fertilizer cost^* to meet OMAFRA recommendations for phosphate can be seen in the P₂O₅ table (see Table 1).

Cost Saving Calculations:

• Soil P levels of 8-9 ppm: 50 acres x 62 lb/ac x $1.00/lb P₂0₅ = $3,100
  
  
• Soil P levels of 21-25 ppm: 50 acres x18 lb/ac x $1.00/lb P205 = $900
  
  
• Soil P levels of greater than 31ppm = $0

Results:

By not crediting the existing fertilizer level in the soil, you could be spending as much as $3,100 more than necessary in this 50 acre field.

*Prices for P₂0₅ and K₂0 are 1.00 and 0.50 $/lb respectively as reported in June 2008 Ridgetown College survey of agriculture inputs.

Scenario 2: Potash

Assume there are three 50 acre fields in corn with different soil potassium (K) levels, and the fertilizer cost^* to meet OMAFRA recommendations for soluble potash can be seen in the K₂O table.

Cost Saving Calculations:

• K field values of 31-45 ppm: 50 acres x 125 lb/ac x $0.50/lb K₂0 = $3,125
  
  
• K field values of 101-120 ppm: 50 acres x 27 lb/ac x 0.50/lb K₂0 = $675
  
  
• K field values of greater than 31 ppm = $0

Results:

By not crediting the existing fertilizer level in the soil, you could be spending as much as $3,125 more than necessary in this 50 acre field.

^*Prices for P205 and K20 are 1.00 and 0.50 $/lb respectively as reported in June 2008 Ridgetown College survey of agriculture inputs.

Table 1. P₂O₅ and K₂O Recommendations for various crops and soil test values

Tables adapted from Nutrient Management Workbook 2003