Enhancing Soil Aggregation with Calcium Ions in Western Canadian Soils

SOIL PHYSICSREGEN AG

Darcy M. Lepine

1/2/20245 min read

a small plant sprouting out of the crack in the ground
a small plant sprouting out of the crack in the ground

Discover how calcium ions enhance soil aggregation in Western Canadian soils and address the challenges of low EC water. Learn about the role of different clay minerals, the effects of ionized calcium, and how gypsum and lime can amend soil to improve structure and productivity.

The Role of Calcium in Soil Aggregation

Calcium plays a pivotal role in soil aggregation through several mechanisms:

  1. Flocculation: Calcium ions promote flocculation, the process where dispersed clay particles come together to form larger aggregates. Ca²⁺ reduces the repulsive forces between clay particles, allowing them to stick together more effectively in larger, nonreactive aggregates.

  2. Cation Exchange Capacity (CEC): Clay particles have a high CEC, meaning they can hold and exchange a lot of cations. Calcium ions can replace other cations like sodium (Na⁺) on the clay surfaces. Sodium tends to disperse clay particles, leading to poor soil structure, while calcium promotes aggregation.

  3. Improved Soil Structure: Aggregation of clay particles improves the soil structure, making it more porous. This enhances water infiltration, root penetration, and air circulation, which are beneficial for plant growth.

  4. Stabilization of Organic Matter: Calcium ions help stabilize organic matter within the soil aggregates. This organic matter acts as a binding agent, further aiding in the formation and stability of soil aggregates.

  5. Reduction of Soil Erosion: Better soil aggregation reduces the risk of soil erosion. Larger more stable aggregates are less likely to be detached and carried away by water or wind.

Impact of Low EC Water on Soil Aggregation

Irrigating soil with low electrical conductivity (EC) < 0.2 ms/cm water or rainwater can strip away essential calcium and other cations from soils top 1 inch layer, leading to surface collapse and the formation of a thin crust. This crust impedes gas exchange and subsequent water infiltration rates, affecting root health and overall soil functionality gradually over the season.

Remediation with Ionized Calcium

Ionized calcium can effectively remediate the problems caused by low EC water. Ionized calcium helps restore cation balance in the soil, promoting flocculation and preventing surface crust formation. When combined with fully humified organic matter rich in humic substances, calcium helps bridge and stabilize the connection between carbon, calcium, and clays.

Amending Soil with Gypsum and Lime

While ionized calcium addresses surface issues, gypsum and lime can amend the deeper layers of soil. These amendments add calcium ions to the soil, helping improve structure and aggregation throughout the soil profile.

The Influence of Clay Mineralogy on Soil Aggregation in Western Canada

The type of clay minerals present in soil significantly affects how calcium influences soil aggregation. Western Canadian soils contain a variety of clay minerals, each interacting with calcium in unique ways, impacting soil structure and properties.

Kaolinite in Western Canadian Soils

  • Properties: Kaolinite has a low cation exchange capacity (CEC) and low surface area compared to other clay minerals.

  • Calcium Interaction: Kaolinite's limited ability to hold cations means it doesn’t retain calcium as effectively as other clay minerals. Consequently, calcium-induced aggregation is less pronounced.

  • Aggregation: Aggregates formed are generally more stable, but the overall impact of calcium is moderate due to the lower reactivity of kaolinite.

Illite in Western Canadian Soils

  • Properties: Illite has a moderate CEC and surface area.

  • Calcium Interaction: Calcium can be exchanged with other cations on illite surfaces, promoting flocculation and aggregation.

  • Aggregation: Illite supports moderate soil aggregation through calcium interactions, improving soil structure but not as dramatically as some other clay minerals.

Montmorillonite in Western Canadian Soils

  • Properties: Montmorillonite has a high CEC and a very high surface area, with a significant ability to swell and shrink.

  • Calcium Interaction: Montmorillonite can hold large amounts of calcium ions, leading to strong flocculation and aggregation effects. The high reactivity makes calcium particularly effective in stabilizing these clays.

  • Aggregation: This clay type shows significant aggregation with the presence of calcium, leading to improved soil structure and stability. However, the swelling and shrinking can still cause structural instability under certain conditions.

Vermiculite in Western Canadian Soils

  • Properties: Vermiculite has a high CEC, high surface area, and good swelling properties, though less than montmorillonite.

  • Calcium Interaction: Similar to montmorillonite, vermiculite can retain a substantial amount of calcium ions, promoting strong flocculation and aggregation.

  • Aggregation: Vermiculite exhibits substantial improvement in soil aggregation when calcium is present, enhancing soil structure and porosity.

Smectite Clays in Western Canadian Soils

  • Properties: Smectite clays, which include montmorillonite, have extremely high CEC and surface area. They are known for their significant swelling and shrinking capabilities.

  • Calcium Interaction: Smectite clays interact very strongly with calcium due to their high CEC. Calcium ions replace sodium and other cations, leading to enhanced flocculation and aggregation.

  • Aggregation: These clays show marked improvements in soil aggregation with calcium, significantly enhancing soil structure. However, their tendency to swell and shrink can lead to some instability under varying moisture conditions.

Practical Implications for Soil Management

Understanding the dominant clay mineral in Western Canadian soils can inform management practices:

  • High CEC Clays (e.g., Montmorillonite, Smectite Clays, Vermiculite): These clays interact more strongly with calcium, leading to better aggregation and soil structure due to their ability to hold and exchange large amounts of cations.

  • Low CEC Clays (e.g., Kaolinite): These clays benefit from calcium but to a lesser extent due to their limited capacity to retain cations.

Recommendations for Soil Improvement

  • Addressing Low EC Water Issues: To mitigate the impact of low EC water, apply ionized calcium to restore surface cation balance and prevent crust formation.

  • Soil Management: Soils with high smectite or swelling clay content may benefit more from calcium amendments (like gypsum) to improve aggregation and structure, however, caution is needed in bringing a clayey-smectite soil recently treated with Ca and organic matter under cultivation. Allow adequate time for aggregate improvement through Ca bridging. Ideally through fall applications.

  • Amendment Selection: The type and amount of calcium amendments might be adjusted based on the clay mineralogy to achieve optimal soil improvement.

Introducing Infiltr8 Soil Health Primer

For effective remediation of water infiltration and soil crusting issues, consider trying Infiltr8, a specialized product containing calcium ions and specialized surfactants. Applying 2-4 gallons per acre of Infiltr8 can improve water infiltration and prevent the formation of soil crusts, helping to create a strong foundation for plant roots.

This product is not a replacement for a good liming regime, but solves a specific issue when dealing with clays in soils and Low EC water. Infiltr8 works by delivering ionized calcium with the help of surfactant technologies directly to the soil surface and ensuring its migration into the top inch of the soil profile. This application replaces stripped calcium ions that low EC waters such as snow melt, rain, and some irrigation waters, pull into the soil solution and collapse soil surfaces forming crusts.  Combining surfactant charged ionized calcium with slow release forms like lime or gypsum, provide the best of both worlds for maintaining good soil structure throughout the growing season.

The Take Away

The mineralogy of clay significantly affects the interaction with calcium and thus influences soil aggregation. High CEC clays like smectite clays (including montmorillonite) and vermiculite show more pronounced improvements in aggregation when treated with calcium, enhancing soil structure and stability, although the effects take longer than other clay soils. Understanding these interactions is crucial for optimizing soil health and agricultural productivity in Western Canadian soils, especially in the context of low EC water challenges.

Related Stories