Aragonite soil amendment.
An OMRI Listed marine calcium carbonate for soil-test-driven calcium and pH programs, supplied as AG-CAL at 0.2–0.5 mm.
A marine calcium carbonate, sized for the spreader.
Oolitic aragonite is a naturally precipitated, marine-origin calcium carbonate that occurs as rounded, layered ooids.
- Mineral form. It is the orthorhombic aragonite polymorph, distinct from the calcite common in quarried limestone.
- Processing. It is collected, dried, screened and sized without chemical synthesis or calcination.
- Composition
- 96.17% CaCO3Representative analysis, ASTM C 25, Bowser-Morner report 124914A.
- Elemental calcium
- 38.51%Representative analysis, same report and method; the basis for the calcium contribution in a rate calculation.
- AG-CAL sizing
- 0.2–0.5 mmPublished range for the agricultural grade; custom classification to customer specification across 20–325 U.S. mesh.
- OMRI listing
- avw-23214Crop fertilizer listing; the livestock feed-material listing is avw-23215.
What it does in soil
Two effects worth separating: calcium and acidity.
A carbonate amendment supplies calcium and neutralizes acidity, and those are not the same job. Which one governs your program comes out of the soil test, not the product label.
Calcium supply
At 38.51% elemental calcium, the material contributes calcium to the program. Whether the crop needs it is a question for the soil test and the complete fertility plan.
Acidity neutralization
As a carbonate it supplies alkalinity and can buffer acidic soils. Soil pH, reserve acidity, neutralizing value, rate and contact time determine the field response.
- Condition-dependent reactivity. Aragonite can dissolve more readily than calcite under comparable acidic test conditions. Particle size, moisture, placement and field conditions all bear on what happens in the ground.
- Handling and spreading. The delivered particle distribution and moisture govern flow, dust, blend uniformity and spreader settings across the intended application equipment.
The soil test sets the rate — the grade follows it.
- Soil analysis — current pH, buffer pH or reserve acidity, calcium status, exchange capacity and salinity.
- Crop and target — the crop, the pH window it wants and the calcium target the fertility plan is working toward.
- Rate and placement — calculated from the soil test and neutralizing value, not from a general recommendation.
- Timing and incorporation — when the material goes on and whether it is incorporated, which shape the response interval.
- Application equipment — the spreader or blending system the delivered particle distribution has to suit.
- Monitoring plan — the soil-test interval that will show whether pH and calcium moved as intended before the program scales.
Material comparison
Aragonite, agricultural lime and gypsum.
The three materials most often weighed against each other in a calcium program do different things. Compare the delivered material and its documentation, not the category name.
| Decision factor | Oolitic aragonite | Agricultural lime | Gypsum |
|---|---|---|---|
| Chemistry | Natural marine CaCO3, aragonite polymorph | Calcite, CaCO3 (calcitic lime), or dolomite, a calcium magnesium carbonate (dolomitic lime) | Calcium sulfate (CaSO4) |
| pH effect | Supplies alkalinity, buffers acidic soils | Supplies alkalinity, buffers acidic soils | None |
| Calcium basis | 38.51% elemental calcium | Grade- and source-dependent | Hydration- and grade-dependent |
| Reactivity | Condition-dependent; compare the delivered grade | Condition- and grade-dependent | Soluble, but does not neutralize acidity |
| Organic programs | OMRI Listed, crop fertilizer listing avw-23214 | Source- and product-dependent | Source- and product-dependent |
Test, trial, then scale.
Test
Start from a current soil analysis and the crop's calcium and pH targets, and calculate the rate against them.
Trial
Apply a representative block at the calculated rate and record coverage, handling and initial soil response.
Monitor
Re-test at the locally appropriate interval to confirm pH and calcium movement before the program goes farm-wide.
Frequently asked questions.
What is an aragonite soil amendment?
It is a calcium carbonate soil amendment made from natural oolitic aragonite — a marine-origin CaCO3 that forms as rounded, layered grains. It supplies calcium and, as a carbonate, alkalinity that can buffer acidic soils. AragoCor supplies it as AG-CAL at 0.2–0.5 mm.
Does aragonite raise soil pH?
As a carbonate it supplies alkalinity and can buffer acidic soils. How far and how fast pH moves depends on the starting pH, reserve acidity, the particle distribution applied, the rate, moisture and contact time — which is why the rate is calculated from a soil test rather than a general recommendation.
How much calcium does it contain?
Elemental calcium is 38.51%, and composition is 96.17% CaCO3. Both are representative analysis by ASTM C 25 from Bowser-Morner report 124914A.
Can it be used in organic production?
It is OMRI Listed under crop fertilizer listing avw-23214, which supports use in qualifying organic programs. OMRI operates a listing program rather than a certification, and the determination for a specific operation rests with your certifier.
How does it compare with agricultural lime?
Both are carbonates. Ag lime is ground limestone: calcite, the trigonal calcium-carbonate polymorph (calcitic lime), or dolomite, a calcium magnesium carbonate (dolomitic lime). This material is the aragonite polymorph of calcium carbonate, marine in origin, with rounded oolitic grains and a documented 96.17% CaCO3 composition. Under comparable acidic conditions aragonite can dissolve more readily than calcite, though particle size and field conditions also govern the result.
The aragonite versus agricultural lime page sets the two side by side in detail.
What particle size is supplied?
AG-CAL is 0.2–0.5 mm, a published range. Where an application or spreader calls for a different distribution, custom classification to customer specification is offered across 20–325 U.S. mesh.
Where to go next.
Discuss a soil, crop and blending program.
Send the soil analysis, crop, target response, volume and destination, and AragoCor will match a grade and quote against the program.