title: Orthophosphate Leaching in St. Augustinegrass and Zoysiagrass Grown in Sandy Soil under Field Conditions.
abstract: Phosphorus (P) is required to maintain healthy, high-quality, warm-season turf. However, excessive P applications to soils with poor P retention capabilities may lead to leaching losses to groundwater. This field study was conducted to determine the maximum P fertilizer application rate to (Walt.) [Kuntze] 'Floratam' St. Augustinegrass (St. Augustinegrass) and 'Empire' zoysiagrass (zoysiagrass) below which P leaching is minimized. Five P levels ranging from 0 to 5.0 g P m yr were surface applied as triple superphosphate. Turf was established on an uncoated, low-P sand with negligible P retention capacity. Leaf and root growth, tissue P concentration, soil P concentration, soil P saturation, leachate volume, and orthophosphate (P) concentration in leachates were measured. Mehlich 1-extractable soil P (M1-P) and soil P saturation ratio (PSR) increased with time as the P rate increased. Lower M1-P and PSR values were measured with St. Augustinegrass, which absorbed more P than did zoysiagrass. The root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching. If tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m yr to zoysiagrass and 1.07 g P m yr to St. Augustinegrass is appropriate and does not result in increased P leaching.
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Gonzalez
authors.forename: Jerry B
authors.initials: JB
authors.lastname: Sartain
authors.forename: Jason K
authors.initials: JK
authors.lastname: Kruse
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Obreza
authors.forename: George A
authors.initials: GA
authors.lastname: O'Connor
authors.forename: Willie G
authors.initials: WG
authors.lastname: Harris
mesh_terms: D005308:Fertilizers; D010710:Phosphates; D010758:Phosphorus; D012987:Soil; D012989:Soil Pollutants
chemical_list: D005308:Fertilizers; D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus