Tuesday, 8 November 2005
6

Cycling of Composted Municipal Biosolids Through Turfgrass Sod.

Xiaoyan Dai, D.M. Vietor, N.E. Hansen, Tony Provin, C.L. Munster, T.W. Boutton, R.H. White, and Frank Hons. Texas A&M University, 370 Olsen Blvd, Soil & Crop Sciences Dept., College Station, TX 77843-3474

High concentrations of dissolved organic C (DOC), P, and N within the harvested layer could contribute leaching losses after transplanting of sod. The fate and transport of DOC, P, and N after transplanting of sod grown with high rates of composted municipal biosolids (CMB) were evaluated in box lysimeters filled with silica sand. Three treatments comprised Tifway Bermudagrass sod transplanted from turf grown with two contrasting compost sources (1.2-cm depth) or inorganic fertilizer (50 kg P/ha). Leachate was collected from 20- and 50-cm depths below the sod surface after eight simulated rain events. The surface layer (0 to 5 cm) and three depth intervals to 50 cm were sampled from the sand medium on three dates. Soil organic C (SOC), total N, delta 13C, soil-test P (STP), and nitrate-N were quantified. In addition, water-soluble organic C (WSOC), DOC, and P in soil or leachate were measured. The CMB imported with transplanted sod significantly increased SOC, WSOC, N, and STP in the 0-5 cm depth compared to fertilizer-grown sod. In addition, SOC and WSOC increased with time at depths to 50 cm after transplanting of each sod source. In contrast, total P and STP were unchanged at depths below 5 cm. The delta 13C values of CMB sources and turfgrass clippings showed contrasting C3 and C4 signatures (delta 13C =-26 to 27.3‰ and delta 13C =-15.2‰, respectively). The delta 13C values of SOC at the 0-5 cm depth increased with time, indicating turf inputs offset decomposition losses of SOC. Total N followed a trend similar to SOC. Leaching losses of DOC from both sources of CMB-grown sod were larger than that of fertilizer grown sod, but losses of dissolved P and nitrate-N did not differ among sod sources.

Handout (.pdf format, 2310.0 kb)

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