Soil Testing Program
GCA is dedicated to helping you realize the maximum value of your crop, not just your fertilizer investment. This can only be achieved if we understand your soil environment and its critical values. Soil sampling is the best way to determine the needs of the crop and help you develop a targeted plan to meet your yield goal. Sampling will help you determine if there are any other factors inhibiting your yield potential.
Why grid sampling and not zone or composite soil sampling?
First, let me say that any method of soil sampling is better than not sampling at all. However, each method has benefits and limitations. So, lets briefly discuss the three main sampling philosophies.
In an ideal world, I would prefer to grid sample within defined EC's of a field. This would produce the most accurate representation of the field.
pH: Amending the soil pH is the single most beneficial thing we can do to raise overall productivity on the farm. This is especially true when we are rotating to crops other than wheat. Wheat breeders in our region have adapted wheat to tolerate fairly acidic soils by selecting varieties that can tolerate soluble Aluminum. However, most other crops that we grow are more sensitive to acidic soils. This represents a potential cropping dilemma. For example, legumes and brassicas are much less suited for low pH soils and generally do not produce as well in those soil environments. Fact is, we do not know until we sample.
Factoid: pH is a logarithmic function of how much Hydrogen is present in the soil. So the difference between 7.0 (neutral) and 6.0 (slightly acidic) is a factor of 10. Whereas, the difference between 7.0 and 5.0 is a factor of 100.
Agronomist perspective: When considering making amendments to a low pH soil, remember that only products that contain Carbonate have the ability to reduce acidity. This is due to a chemical reaction that occurs when the Carbonate reacts with Hydrogen. Hydrogen is pulled off the soil exchange sites by Calcium or Magnesium in the liming material and reacts with Carbonate resulting in CO2 and H2O. Thereby, lowering the free Hydrogen in solution which in turn reduces soil acidity.
When soils are at near neutral 6.0-7.2
Garber Cooperative is your resource for Precision Grid Sampling and Interpretation of Analysis