Water and nutrient retention by Aquasoil® and Stockosorb® polymers

Abstract

Water retention and hydration rate of Aquasoil and Stockosorb polymers, the effects of these polymers on the water, ammonium and nitrate retention of a pine bark growth medium and the response of the polymers to fertilizer solutions were investigated. Aquasoil retained 129 g of distilled water g⁻¹ of polymer, whereas Stockosorb retained 216 g⁻¹ of polymer. Both polymers reached their maximum capacity in about one hour. The polymers when combined with 1 or 2 g 500 g⁻¹ of pine bark, improved the water retention capacity of the growth medium. However, longer time was required in the growth medium for the polymers to reach maximum capacity than in the distilled water. All polymer-amended pine bark media retained more ammonium, compared to non-amended media. The 2 g polymer treatment retained greater amounts of NO₃ than the lower rates. Retention of water by the Aquasoil® and Stockosorb® polymers was reduced to 88% and 86% of capacity compared to distilled water, whereas fertilizer solution reduced water retention to 53% and 42% of capacity. Soaking in distilled or tap water improved water retention of the polymers over fertilizer solutions.

Keywords:

• Ammonium
• growth medium
• nitrate
• polymer
• water