Turfgrass Armoring of Levees Constructed with High Saline Soils within the New Orleans Levee District.

Increased levee construction since 2005 in the New Orleans Levee District has strained clay burrow pit sources.  As a consequence, saline soils (>10 dS m^-1 EC) have been use for levee construction which have resulted in poor turfgrass establishment and highly eroded slopes.  A study was conducted to evaluate turfgrass establishment on a levee slope constructed from saline clay (18 dS m^-1 EC) utilizing two turfgrass species combined with cultural practices. Cultural practice treatments included the addition of organic matter (OM); a gypsum amendment; tillage and irrigation regiment; low saline clay cap (CC); or untreated control.  Seashore paspalum (Paspalum vaginatum) and Arizona common bermudagrass (Cynodon dactylon L.) were hydro-seeded or vegetatively propagated from sprigs.  Eight weeks after establishment, the CC resulted in bermudagrass and seashore paspalum coverage of 54 and 28% when seeded compared to 18% and 16% when sprigged, respectively.  OM resulted in bermudagrass and seashore paspalum coverage of 62 and 44% when seeded compared to 24 and 18% when sprigged.  All other treatments resulted in < 10% turfgrass establishment. Results indicated that clay textural and hydraulic properties limited salt leaching near the soil surface to allow seed germination and sprig growth. Therefore, based on the soil capping results, testing clay for saline concentration prior to installation of the final lift can ensure a suitable soil for turfgrass establishment and armoring.