Effects of Salinity Applied to Seashore Paspalum On Three Simulated Athletic Field Situations: I. Soil Salinity Responses.

With use of more saline irrigation on turfgrass sites, understanding soil and plant responses to salinity becomes important. In this paper the focus is on spatial and temporal soil salinity responses. Sea salt was applied by drop spreader and irrigated into the canopy of ‘SeaIsle 1’ seashore paspalum (Paspalum vaginatum) at 0, 0.66, and 1.32 kg m^-2 under three simulated athletic field soil conditions; studies were classified by soil type: a) sand profile -- sand meeting USGA Green Section greens specifications to a depth of 30 cm, b) sand cap -- 10 cm sand over an Appling sandy clay loam using the same sand as in the sand profile, and c) native soil -- Appling sandy clay loam. Each soil was at field capacity at initiation of the first dry-down on 13 Oct. 2008 and when treatments were reapplied on 21 Oct. 2008 for the second dry-down. No irrigation was applied during either dry-down (13-21 Oct. and 21-27 Oct.), but 2.7 and 3.0 cm rainfalls occurred on 17 and 24 Oct., respectively. Soil salinity was assessed by two devices based on determining bulk soil conductivity (EC_a) at 0-10, 0-20, and 0-30 cm by measuring soil resistivity using the 4-wenner array method: a) experimental mobile soil salinity monitoring device (SMD), and b) LandMapper by Landviser (League City, TX). Soil samples taken on 15 Oct. from the 0-10 cm zone were used for calibration of EC_a by both devices versus EC_e (saturated paste extract) and to conduct routine soil fertility tests by treatment. Plant response was determined by NDVI (normalized difference vegetative index) and visual evaluations. Soil salinity responses over time and in response to rain-induced leaching will be discussed for the three soils, as well as EC_a versus EC_e calibration curves.