Organic Amendments Improve the Establishment of Tall Fescue in a Simulated Urban Soil.

Development is a leading cause of urban soil degradation. The loss of organic matter- and nutrient-rich topsoil and subsequent compaction of subsoil typically results in a poor rooting medium for supporting plant growth. Organic matter- and nutrient-rich biosolids products may be used for renovating such disturbed soils by improving physical and chemical properties.

The objective of this study was to compare various biosolids-based organic amendments and inorganic fertilizer for establishment and production of turfgrass in urban disturbed soils. Exceptional Quality biosolids products compared with soil test recommended-inorganic fertilizer rates were: (1) dewatered anaerobically digested and pasteurized biosolids from Alexandria, Virginia (Alexandria Renew Enterprises, ARE); (2) ARE biosolids blended with sand and sawdust at a ratio of 50% biosolids/25% sand/25% sawdust; and (3) biosolids generated at three wastewater treatment facilities in Spotsylvania County and composted with wood chips (Livingston Compost). All amendments were applied at a target rate of 200 lbs N/ ac.

Research plots were established in September 2013. Two irrigation rates based on 0% and 80% evapotranspiration replacement were applied. Turfgrass color, quality and clipping yield were measured bi-weekly from establishment through the 2016 growing season. During the initial season (September 2013-August 2014), the inorganic fertilizer treatment outperformed the biosolids-based treatments for clipping yield and turf quality in both irrigated and non-irrigated plots. The inorganic fertilizer treatment likely performed better as it was the only application that was split applied during the initial first year. All biosolids treatments were applied at the full target rate prior to seeding in September 2013. During September 2014-June 2015, all treatments were split applied throughout the year. Biosolids products performed as well or better than the fertilizer during this period, likely due to residual effects of the organic products and greater N use efficiency due to split applications. During July 2015-May 2016 no amendments were applied to the trial area to test the effects of a “residual year.”  Once again, biosolids products performed as well or better than the fertilizer during this residual year.