Alkaline Compounds Typically Found in These Soils

 Let's examine the solubility of several compounds found in alkaline soils. The units are moles per liter of water or referred to as Ksp. If the solubility is greater than 0.1 mole/L it is considered soluble. If the solubility is between 0.01 and 0.1 molel/L it is slightly soluble. Any substance with less than 0.01 mole/L is considered insoluble.

Ksp Solubility for Alkaline Salts (mole / liter)

As you can tell from the table above, none of the alkaline salts are soluble in water, even to the slightest degree.

What is the Solution?

Alkaline soils containing any of the above compounds can be solubilized by the additon of acids.

A common management practice involves adding a solution of sulfuric acid to calcareous soils. By doing this gypsum becomes a byproduct of the reaction. The chemical equation is as follows: H₂SO₄ (sulfuric acid) + CaCO₃ (calcium carbonate) → H₂O + CaSO₄ (gypsum) which ionizes into Ca²⁺ and sulfate (SO₄²⁻).

The desired outcome is to increase soluble Ca²⁺ that improves aggregate stability in soils with poor structure.

Another common practice involves applying elemental sulfur on calcareous soils whereby gypsum becomes a byproduct of the reaction. The soil microbes convert the sulfur into sulfuric acid as follows: S (sulfur)+ O₂ + CO₂ + 2H₂O → H₂SO₄ + CH₂O. Then the synthesized sulfuric acid dissolves calcium carbonate and makes gypsum.

Typical timeframe for this process can be several weeks during the winter season and somewhat faster in the warm months.

Soil Restoration of Sodic and/or Saline Soils Using SoilTech

This technique for desalination and reclamation of the alkaline salts involves incorporating products that contain organic acids. A significant advantage is that this approach does not add either sulfuric acid or sulfur into the soil. This eliminates the synthesis of sulfuric acid in the soil therefore eliminates the potential for plant toxicity.

The organic acids dissolve the alkaline salts and frees up soluble Ca²⁺ and Mg²⁺ plus other cations into the soil solution. This improves the structure of the soil by displacing sodium with the ionized Ca²⁺ and Mg²⁺.

Water allows the organic acids to combine with or leach the salt in the soil below the root zone or germinating seed. A huge benefit for this process is that the osmotic potential in the soil should decrease as a result of the treatment.

The organic acid material can be added by any method of irrigation. It can be over sprayed on plant material without adverse effects which means that the organic acids can be incorporated anytime of the year.

What is This Product?

SoilTech is a blend of polyelectrolyte polymers containing organic acid functional groups. The combined molecular weight is over 28,000 (water is 18) therefore providing numerous active groups.

The organic acid groups solubilze alkaline salts such as calcium and magnesium carbonate therefore releasing free calcium (Ca²⁺) and magnesium (Mg²⁺) ions (plus others) into the soil solution. As the freed up calcium and magnesium ions improve the soil structure, the "bad" material such as bicarbonates, sodium, and chlorides are leached below the root zone.

Not only will SoilTech solubilize the alkaline materials, it will help prevent the re-formation of the alkaline salts particularly when applied as a drip irrigation.

SoilTech converts the base cations into usable plant nutrients.

Other notable benefits of improving the soil structure includes increased infiltration and percolation, reduced soil compaction and restoring the proper pore space. One of the obvious benefits is the reduction in water usage because of the increased amount of water percolation.

It has been noted over the years that seed germination increases due to the dissolving of the alkaline material on the surface crust, thus maintaining surface moisture for longer intervals.

Application

 The preferred application method for alkaline soils particularly in the western United States is by continuous and/or drip irrigation. Other methods including use of a boom sprayer has been successful.

The advantage of drip is that SoilTech can be applied at a reduced rate on a continual basis. This will help to keep the alkaline material continually dissolved during and after application.

Application rates and frequencies for soil restoration projects are site specific. SoilTech is non-toxic to plants and soil microorganisms therefore are safe to use.