Thursday, November 16, 2006 - 10:40 AM

Turfgrass Growth and Water Use in Gypsum-Treated Ultisols.

M.J. Schlossberg1, William P. Miller2, and John Kruse2. (1) Penn State University, 116 Asi Bldg, University Park, PA 16802, (2) University of Georgia, 3111 Miller Plant Sciences, Athens, GA 30602

Subsurface acidity, typical in Ultisols of the US Southern Piedmont, often limits turfgrass root growth and stress resistance. The perennial nature of turfgrass and the expectation of its continual utility preclude use of slow, disruptive procedures currently available to lime subsoils. The objective of this greenhouse study was to compare effects of synthetic or mined gypsum (CaSO4), CaCl2, or calcitic lime surface application on growth, nutrition, water-use, and quality of tall fescue (TF) or hybrid bermudagrass (HB) swards. An homogenized upland Piedmont soil (pHw = 4.9) was used to fill 90 PVC columns (70 x 7.6 cm i.d.), half instrumented with moisture probes at 20- and 48-cm depths. Prior to seeding, Ca amendments or lime were applied at rates of 3.6 or 1.9 Mg ha-1 Ca, respectively. High-quality irrigation water was liberally applied each month to mimic typical seasonal leaching conditions. Clipping yield, color, nutrient levels, and leachate quality data were collected regularly. Root length density (RLD) and soil chemical properties were determined by depth 27 months after applications. Leachate data showed rapid solute transport from CaCl2, followed by CaSO4 treatments. Similar total Ca efflux from control and limed columns were just 40 or 15% of respective CaSO4 or CaCl2 levels. Compared to the control, Ca application significantly increased leaf Ca. Compared to control and lime treatments, Ca amendment increased leaf S. Both CaSO4 treatments increased TF shoot growth and deep RLD compared to lime and control treatments. Conversely, HB shoot growth responded more favorably to lime. Water use by depth was better correlated to TF RLD than HB RLD, with the latter species showing variable response to Ca-amendment. Surface applications of CaSO4 appear to effectively ameliorate subsoil acidity to 60-cm soil depths over 2 years of leaching conditions, yet beneficial growth response varies among turfgrass species.