Aragonite/Oyster Shell Flour — premium coral-sea calcium to fuel soil biology.

This natural calcium source nourishes soil microbes and elevates biological activity, unlocking essential nutrients for healthier, more vigorous plants. Ideal for living organic soils, it serves as a pure, natural alternative to lime while supporting a resilient soil ecosystem. From The Soil Makers, crafted to boost nutrient availability and mineral balance across your garden, compost, or raised beds.

• Calcium-rich formula: 97% calcium carbonate and calcium silicate combined; 33–40% available calcium for faster root development and improved uptake.
• Comprehensive trace minerals: includes Fe2O3, Al2O3, MgCO3, SO3, NaCl, SrO, SiO2 to support soil mineral balance.
• Soil-life compatibility: excellent as a calcium source that nourishes soil microbes, enhancing the soil food web and long-term fertility.
• Easy application: use 1–2 cups per cubic foot of soil to complement your broader nutrient and mineral regimen.
• Versatile uses: perfect for living organic soils, gardens, containers, raised beds, and even as a top layer for bocce courts.
• Shipping perks: free shipping on the 45 lb option.

Why choose Aragonite/Oyster Shell Flour from The Soil Makers? This specific calcium formulation supports robust microbial activity, improves nutrient access for plants, and helps maintain mineral balance in organic soil systems. Its natural composition and low magnesium profile make it an effective calcium supplement that fits seamlessly into sustainable gardening practices.

Key specs

• Product category: Home & Garden > Lawn & Garden > Gardening > Fertilizers
• Calcium content: 97% calcium carbonate and calcium silicate combined; 33–40% available calcium
• Minerals: Fe2O3 0.025%, Al2O3 0.15%, MgCO3 1.50%, SO3 0.20%, NaCl 1.25%, SrO 1.25%, SiO2 0.88%
• Use recommendation: 1–2 cups per cubic foot of soil
• Form: Aragonite / Oyster shell flour
• Brand: The Soil Makers

This product serves as an excellent source of calcium and nourishment for soil microbes. It enhances biological activity in the soil, improving the availability of essential nutrients and minerals to your plants. Ideal for living organic soils, it offers a pure and natural calcium alternative to Lime. Use 1-2 cups per cubic foot of soil to complement a comprehensive nutrient and mineral regimen.

Enjoy free shipping on the 45 lb option!

ALSO WORKS AMAZING AS A TOP LAYER FOR BOCCE COURTS