Fate and transport of nitrogen applied to six warm-season turfgrasses

A greenhouse study compared six warm season turfgrasses common bermudagrass [Cynodon dactylon (L.) Pers.], 'Tifway' hybrid bermudagrass (C. dactylon x transvaalensis), centipedegrass (Eremochloa ophiuroides (Munro) Hack.), 'Raleigh' St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze], 'Meyer' zoysiagrass (Zoysia japonica Stead.), and 'Emerald' zoysiagrass (Z. japonica X tenulfolia) for NO(3)-N leaching and N use efficiency. Sod was established in sand-filled columns and managed under worst-case conditions to promote nitrate leaching. Ammonium nitrate was applied at 50 kg N ha I on seven dates, with the final application labeled with IN. Leachate samples were collected and analyzed for NO(3)-N and NH(4)-N and clippings were analyzed for total N. Leaching losses were high following the first N application, ranging from 48 to 100% of the NO(3)-N and 4 to 16% of the NH(4)-N applied. Nitrate loss from subsequent applications was reduced substantially, while NH(4) leaching was essentially eliminated. There were significant differences among species for leachate NO(3)-N concentration and cumulative N leached, with St. Augustinegrass being the most effective and Meyer zoysiagrass the least effective at minimizing NO(3) leaching. Nitrogen recovery by the turf ranged from 63% for Meyer zoysiagrass to 84% for hybrid bermudagrass. Root length density (RLD) varied significantly among species at depths >30 cm, and was negatively correlated with NO(3) leaching loss. These results document differences between the warm season turfgrasses for NO(3) leaching potential, possibly related to root distribution, and emphasize that species selection is an important factor in minimizing environmental impacts from turfgrass management.