Phosphorus in Hawaiian Kikuyugrass Pastures and Potential Phosphorus Release to Water.

This article focuses on the phosphorus (P) content in Hawaiian kikuyugrass pastures and examines the potential phosphorus release to water. Pasture systems in Hawaii are based primarily on kikuyugrass. More specifically, kikuyugrass is the most widespread pasture grass in Hawaii and is common in tropical highland and subtropical environments throughout the world. This species is highly efficient in utilizing soil P and deficiencies appear to occur only in very P-infertile soils. Relationships among kikuyugrass P concentration, animal P requirements, and various soil P determinations are needed to help identify source areas for implementing pasture management strategies to limit P loss via overt land flow. A total of 51 rotationally stocked kikuyugrass pastures with contrasting soil chemical properties were sampled. The current study suggests that while Hawaiian kilruyugrass pastures tend to be sufficient to high in forage P, potential soil P release to water only appeared to be a possible environmental concern for the mollisol and inceptisol sites.