Soil Sample Interpretation

1. Soil PH
> Ideal pH for most crops is about 6.8. Try to keep within 0.5 of that.
> High pH – above 7.3
A. Drainage problems are often the cause
B. Tile, Zone Build, and surface ditch where possible
C. Band Element sulfur – Temporary change
> Low pH – below 6.3
A. Lime affected areas
B. Watch subsoil pH tests, as well.

2. Base Saturation: 5 measurements = 100%
> Calcium (Ca) (65% to 80%
- If Calcium levels are low, add lime
> Potassium (K) (4 to 8%)
- If K level is low, add Mg
> Magnesium (Mg) (12% to 25%)
- If Mg level is low, add Mg
- If Mg is high, improve drainage & add sulfur (if necessary)
> Hydrogen (H) (<10%)
- If H is high, add lime (calcium carbonate)
> Sodium (Na) (<1%)
- If Na is high, improve drainage & decrease manure or other high salt applications

3. Cation Exchange Capacity (CEC)
> Tells you the holding capacity of your soil
> The 3 components of CEC are:
Type of Clay
Amount of Clay
Amount of Organic matter

> CEC is used for many things, but 1 simple thing you can use it for is nitrogen application. A soil will only hold approximately 10 times the CEC. For example, if you are CEC are 8, 8 times 10 equals 80 pounds of nitrogen. If you are raising 150-bushel corn, you need approximately 150 pounds of nitrogen. This means that all that nitrogen CANNOT be applied in 1 application.

4. Primary Nutrients
> Nitrogen (N)
A. Leachable
B. Corn-on-corn add at least 50 lbs extra for tie-up on 2nd year corn
>  Phosphorus (P)
A. pH below 7 – look at Bray test
> P1 is available P
> P2 is total P (available + reserve)
B. pH above 7 – look at Olsen test
> Only measures available P
C. Potassium (K)
> Base sat percentage of 4% or higher is key
5. Secondary Nutrients
> Sulfur (S)
> Less pollution means less sulfur for farmers
> Leaches (moves down) easily in most soils
> Calcium (Ca) – Large molecule, high levels are needed
> Magnesium (Mg) – Small molecule, Soils high in magnesium is typically tight, poorly drained, and prone to compaction problems.

6. Micro Nutrients
> Zinc (Zn) – does not move much in soil
> Boron (B) – leaches easily in most soils
> Manganese (Mn) – talked about often with Roundup crops
> Copper (Cu)
> Iron (Fe)