Is 10-10-10 Organic? And When SOP Granular Potash Makes More Sense

Gardeners ask me every season about 10 10 10 fertilizer organic options. Short answer: true organic 10-10-10 blends are rare and often pricey. In practice, many sustainable growers build a “balanced” program by pairing composted or natural nitrogen and phosphorus with a chloride-free potassium source such as SOP (sulfate of potash). That’s where this product comes in.

Product at a glance: Potassium sulfate SOP fertilizer granular 52% K2O

Origin: A-713, Zhengyang City Square, Chang'an District, Shijiazhuang, Hebei, China. It’s a clean, granular SOP—low salt index, chloride-safe for berries, grapes, citrus, potatoes, and even greenhouse crops. In fact, many customers say yields tick up when they switch away from muriate of potash.

How it’s made (process flow)

Materials: potassium chloride and sulfuric acid. Method: Mannheim process → reaction to potassium sulfate + HCl → neutralization → granulation → drying → screening → anti-caking → bagging. QC: K2O assay (ICP-OES, AOAC methods), moisture (gravimetric), chloride (ion chromatography), particle size distribution (sieve analysis), heavy metals per AAPFCO/EN guidance. Batches are retained and tested before shipment.

Application scenarios

• Chloride-sensitive crops: berries, grapes, tobacco, potatoes, cucurbits, ornamentals.
• Fertigation and hydroponics: dissolves cleanly; check emitter compatibility.
• Transitioning from 10 10 10 fertilizer organic: pair SOP with organic N (e.g., feather meal) and natural P (e.g., rock phosphate) to “balance” the program.

Rates: often 50–150 kg/ha per application; to be honest, calibrate to soil/tissue tests and yield goals. Split applications help during fruit set and bulking.

Is it “organic”?

Some SOP products are OMRI-Listed, but not all. Always verify current OMRI or equivalent certification before using in certified organic systems under USDA-NOP. This specific SKU should be checked for documentation at purchase.

Advantages vs “balanced” blends

• Precision: match K and S without overloading N and P like some 10-10-10s.
• Quality: better color, brix, and storability reported on fruit; less leaf burn than MOP.
• Water-soluble and low chloride—safer in greenhouses and sandy soils.

Vendor comparison (indicative)

Customization and testing

Custom NPK blends to emulate 10 10 10 fertilizer organic programs are feasible using SOP + approved N/P sources. Batch CoAs can reference AOAC methods for K and S, and alignment with AAPFCO definitions. Ask for heavy metal screening per regional norms.

Case notes (real farms, quick take)

• Blueberry farm (sand soil): replaced generic 10-10-10 with SOP + fish hydrolysate; leaf burn issues disappeared, yield +7% season two.
• Table grapes: SOP during veraison improved color and lowered chloride leaf tissue values versus MOP program.

Certifications and compliance: Verify OMRI listing for organic eligibility; for food crops, follow USDA-NOP and local residue limits. Storage: dry, covered, pallets off floor to avoid caking. Always base rates on soil/tissue tests.

Authoritative citations

1. OMRI. Organic Materials Review Institute. https://www.omri.org
2. USDA National Organic Program (NOP). https://www.ams.usda.gov/rules-regulations/organic
3. AAPFCO Official Publication. https://www.aapfco.org
4. AOAC Official Methods for Fertilizers and Soils. https://www.aoac.org
5. FAO: Fertilizer use by crop. https://www.fao.org
6. Fertilizer Europe: Nutrient stewardship in potassium fertilization. https://www.fertilizerseurope.com