Kinsey Agricultural Services

What is the best course of action to take in order to correct high sodium levels in our soils?

The first thing to do is to determine for sure that high sodium is actually a problem. This may sound strange, but some growers we have worked with have assumed the sodium in their soil was high when that was actually not the case at all. Most people believe that when the soil has a very high pH it is because there is a sodium problem. But this is not always the case.

Elements Other Than Sodium Can Cause High pH

It is true that most soils with a very high pH have high to excessive sodium levels. But there are soils that have such excessive amounts of magnesium and/or potassium that are actually causing the problem, yet sodium receives the blame.

The only way to know for sure if sodium is a problem is by measuring the actual amounts of it, along with calcium, magnesium and potassium, in order to understand which of them is adversely affecting the pH level in each soil. Every soil has a specific need for each of these elements based on the nutrient-holding capacity of that particular soil. This can always be accurately determined when a soil test is correctly pulled and sent to be analyzed.

No Two Labs Provide the Same Analysis

The prevailing opinion in soil fertility management today is that one soil test is not that different from another and each will provide enough of the correct information to make an informed decision.

Before you accept that as fact, perform your own test. Using two sample bags, take side-by-side cores of soil from at least 5 different places in a given area of uniform soil fertility (see Taking a Good Soil Sample). Send one to us and one to another lab that you decide would be a good one. Ask for an analysis plus recommendations from each one. Take note of how different the analysis and recommendations are by comparison. It is not our intent to be different, but it is our intent to give correct advice.

Test Your Soil-Tester!

The only way you may know for sure who is right is by setting aside land on which you do both programs for three years to see which one makes the most difference. For an accurate determination be sure to correctly follow through and do all that is recommended for that particular soil.

If Sodium Is In Excess

After it is determined that too much sodium is actually the problem, it should next be determined what the soil is actually lacking, before the proper corrective action can be taken. The best way to solve an excess of something in the soil is by supplying any necessary amounts of those elements that are deficient, the excess will tend to be automatically reduced.

Check Calcium levels!

The next consideration should be whether or not the soil contains enough calcium, because adequate calcium actually increases soil flocculation thus helping to increase soil porosity and allowing sodium to be leached more readily from the soil.

Sulfur or sulfates, including gypsum, should not be used to rid a soil of sodium until the soil’s calcium saturation is at least 60% or higher. If below 60%, this would require limestone, finely ground oyster shell, laying-hen manure or some other source of material that principally builds calcium levels. Do not consider gypsum in such cases due to the high sulfur content, until sufficient calcium to reach 60% saturation of the soil has been added. (An exception would be the lighter soils such as sands where adding a ton or less of gypsum by itself would increase the calcium level in that soil to 64% or higher.)

Then Consider Gypsum

Once 60% calcium has been achieved, gypsum, at one ton or less per acre per year, would be the material of choice to use on soils with too much sodium until the calcium reaches the maximum saturation for that particular soil. Again, this should be part of a determination made by the soil test used. Once that point is reached, sulfur and sulfate fertilizers without calcium can still be used in moderate amounts to decrease any remaining excess of sodium. Specific amounts would depend on the actual soil analysis from the land in question.

The above % figures relate to soil tests that we process, the soil analysis from other labs will be different, and the guidelines given above will not be specifically valid if such is the case.