Thursday, November 8, 2007 - 8:15 AM
337-2
Tall Fescue Root and Shoot Response to Gypsum Treatment of Acid Soil.
Subsurface acidity, typical of Ultisols worldwide, often limits nutrient acquisition, root elongation, and drought tolerance of typically-deep-rooting turfgrass species. The objective of this greenhouse study was to compare effects of CaCl2•2H2O, calcitic lime, or either anthropogenically-synthesized or mined gypsum (CaSO4•2H2O) surface application on growth, nutrition, and quality of tall fescue, TF (Festuca arundinacea Schreb.). An homogenized upland SE US Piedmont soil (pHw = 4.9) was used to fill 30 polyvinyl-chloride columns (70 x 7.6 cm i.d.). Prior to seeding, amendments or lime were surface-applied at rates of 3600 or 1900 kg Ca/ha, respectively. Potable irrigation water was liberally applied each month to mimic seasonal leaching conditions. Density and growth of TF shoots, and elemental concentrations of leaf tissue and leachate were regularly measured. Root length density (RLD), branching, and specific root length (SRL) of TF were determined (by depth) 27 mo following treatment applications. Leachate data showed rapid solute transport from surface applications of CaCl2, followed by CaSO4. Either CaSO4 treatment significantly increased TF leaf Ca compared to the control, and increased TF leaf S compared to control and lime treatments. Either CaSO4 treatment significantly increased TF shoot growth; as well as RLD, SRL, and branch number in roots recovered from the 39-62 cm soil depth, compared to lime or control treatments. Over 2 y of leaching conditions, 16 000 kg/ha surface applications of CaSO4 improved TF vigor through enhancement of root growth in acidic subsoil horizons as deep as 60 cm. Subsurface acidity within maintained TF systems may be more effectively ameliorated by surface applications of gypsum or gypsum/lime combinations, than by traditional liming agents alone.
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