Independent lab analysis from 2025 shows Holloway Gypsum is the smart choice for California growers 
In the summer of 2025, Holloway’s agronomy team had five different forms of gypsum analyzed by an independent third-party lab (Wallace Laboratories), including:
- Competitor A – 83% gypsum product
- Competitor B – 90% gypsum product
- Competitor C – 90% gypsum product
- Competitor D – 100% gypsum product
- Holloway – 55% gypsum product
Analysis Summary
Holloway’s 55%, organic and naturally mined gypsum outperformed others in that it contained only high-quality Dihydrate Gypsum, or Calcium Sulfate (CaSO4+2H2O), versus Anhydrite (CaSO4).
Holloway’s 55% also outperformed others in terms of micronutrients content, and tested out as a cleaner soil amendment without significant levels of lime or dolomite.
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