Enhancing Phosphorus Phytoremedation Potential of Two Warm-Season Perennial Grasses with Nitrogen Fertilization

Phytoremediation or use of plants to extract soil nutrients is a practice used to ameliorate the impacts of excessive soil nutrients. Pensacola bahiagrass (Paspalum notatum Fliigge) and 'Floralta' limpograss [Hemarthria altissima (Poir.) Stapf & Hubb] were grown in a P-impacted Immokalee fine sand (Mehlich-1 P ≈ 30 mg P kg -1 ) to evaluate increasing N levels on dry matter yield (DMY), forage P concentration, P removal, and P dynamics in the soil profile. Treatments were four levels ofN fertilization (0, 50, 67, and 101 kg N ha -1 harvest -1 ) replicated four times for each species. Both grasses showed increases in P removal with increasing N fertilizer applications. Phosphorus removed by forages for the highest N application level ranged from 59 (bahiagrass; 2-yr period) to 83 kg ha -1 (limpograss; 3-yr period). The initial soil P content of the Ap horizon of all N > 0 treatments decreased by ≥85% over the study period. However, more P from the control (N = 0) plots leached to subsurface horizons compared to P lost from the plots receiving N fertilizer. Nitrogen application enhanced P uptake from the soil and consequently reduced off-site P losses from the surface soil. Nitrogen application of 67 kg ha -1 harvest -1 optimized P removal by bahiagrass and limpograss. These data show that well managed, warm-season perennial forage grasses with adequate N fertilization and managed for hay production or greenchop are an option for reducing off-site P losses from P-impacted soils.