Phosphorus Forms and Availability in Organically Managed Grassland Soils.

Phosphorus (P), an essential element for plants and animals, can be a limiting nutrient in organically-managed soils. The objective of this research is to determine P forms and availability in certified organic grasslands at the WVU Organic Research Farm. We compared three management systems (Pasture, Buffer, and Hay) each at two levels of fertility (High and Low). Phosphorus forms were determined by sequential fractionation with H2O, NaHCO₃, NaOH and HCl. Phosphorous availability was determined using several common soil test procedures. In addition, physical and chemical properties such as pH, EC and soil texture were determined. The results showed higher soil test extractable phosphorous in high fertility plots of hay and pasture. The P content in hay and pasture systems were found to be significantly different with Mehlich1 and Morgan extraction procedure. We also found that NaOH extracted highest amount of phosphorous followed by NaHCO₃ and HCL.