Plant Science Concepts OSA/28 - 4oz Bioavailable silicon fertilizer (monosilicic and orthosilicic acid) OSA/28 contains silicic acid, the only plant available form of silicon, an important element that strengthens cell walls, increases nutrient uptake, and increases plant immune response. OSA/28 is the $58.00 MPN: OSA28 - 4oz UPC: 747906965636 Product category: Home & Garden Product type: Specialty Plant Fertilizer Availability: In stock |