Short-Term C-Fluxes In Biosolid-Amended Soils During Turfgrass Establishment.

Soils amended with biosolids for sod production may enhance sustainability and offset fertilizer needs. The effect of biosolids additions on CO₂ flux and NO₃^--leaching during establishment is unknown. The objectives of this study were to evaluate gaseous C-flux and NO₃^--leaching potential from biosolids-amended soils during turfgrass establishment. The experimental design for the 16-week greenhouse study was a split-plot, randomized block with five replications. Main plots consisted of 200 kg Plant Available N (PAN) ha^-1 from urea plus 0, 100, 200, or 400 kg PAN ha^-1 from biosolids. Biosolids were incorporated into silt loam soil; subplots consisted of vegetated (with Kentucky bluegrass; Poa pratensis L.) and non-vegetated treatments. Biosolids amendments increased CO₂ efflux for about 12 weeks. Vegetation produced net soil C gain  during two sampling periods at times of rapid growth after which it declined rapidly presumably due to higher temps that increased turf respiration while decreasing photosynthesis. Biosolids additions increased turf quality and plant aboveground biomass without increasing the amount of C in the plants on a dry matter basis. Biosolids did not influence soil C other than that derived inherently from the biosolids. NO₃^- concentration in leachate decreased with time and vegetation and was not affected by biosolids.