Wednesday, November 7, 2007
245-11

Cycling of Solids from a GeotubeŽ Dewatering System through Turfgrass Sod.

Ronnie Schnell1, Donald Vietor1, Clyde H. Munster2, Richard H. White3, and Saqib Mukhtar4. (1) Texas A&M University - Soil & Crop Sciences, College Station, TX 77843-2474, (2) Texas A&M University, Biological & Agricultural Engineer, College Station, TX 77843-2117, (3) Texas A&M University, 2474 TAMU, College Station, TX 77843-2474, (4) Agricultural Engineering, Texas Cooperative Extension, College Station, TX 77843-2117

Solids separated from dairy lagoon effluent in a GeotubeŽ Dewatering System could be applied to agricultural crops, including turfgrass sod. Yet, injection of Alum and polymers during wastewater delivery to Geotubes could affect crop responses to residual solids. The first objective was to analyze physical and chemical properties of solids remaining in Geotube Dewatering Systems after wastewater drains through the porous fabric. The second objective was to evaluate turfgrass establishment and growth responses and physical, chemical, and biological properties of contrasting soil textures with and without incorporation of Geotube residue. The final objective was to evaluate leaching losses of nutrients and dissolved organic carbon from contrasting soil textures with and without incorporation of Geotube residue during turfgrass establishment. The experimental design comprised four replications of four combinations of two volume-based rates of Geotube solids (12.5% and 25% by volume) and two contrasting soil textures (Windthorst fine sandy loam and Westwood silt loam), plus controls without solids. The solids were incorporated to a 10-cm soil depth within column lysimeters (10-cm diameter x 30-cm depth). All treatments were sprigged with Tifway bermudagrass (Cynodon dactylon L. Pers. X C. transvaalensis Burtt-Davey). One pore volume of leachate was displaced and collected at each 45 and 90 days after sprigging. Soil, Geotube solids, turfgrass biomass, and leachate were sampled, and analyzed to quantify physical properties and concentrations and mass of N, P, cations, and organic carbon. Variation of soil bulk density and water content among rates of solids and soil textures will be reported. In addition, turfgrass growth responses to solids and relationships to soil physical properties will be presented. Leaching losses of N, P, cations, and dissolved organic C will be related to rates of solids, soil texture, and soil concentrations of nutrients and organic C.