Research Summary
Organic Amendments Improve Tall Fescue Lawn Performance in Urban Soil Virginia Tech Researchers: Mike Badzmierowski, Ph.D. Student; Gregory Evanylo, Ph.D., Professor and Extension Specialist; and Erik Ervin, Ph.D., Professor of Turfgrass Culture & Physiology Research Sponsors: Metropolitan Washington Council of Governments and Virginia Agricultural Experiment Station
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evelopment is a leading cause of urban soil degradation. The loss of organic matter and nutrient-rich topsoil and the subsequent compaction of subsoil typically result 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 disturbed urban 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/acre. 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),
24 | Virginia Turfgrass Journal May/June 2016 www.vaturf.org
fertilizer treatment outperformed the biosolids-based treatments for clipping yield and turf quality in both irrigated and non-irrigated plots. Fertilizer likely performed better than biosolids because nitrogen supplied by the split applications of fertilizer were more efficiently used than that supplied by the biosolids treatments, which were applied entirely prior to planting in September 2013. During September 2014 – June 2015, all nutrient sources 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 period. In June 2016, a Blue Plains dewatered and air-dried biosolids product to be marketed as “Bloom” was substituted for the ARE dewatered biosolids. A biosolids-sand-sawdust ratio of 1.5:1:1 was substituted for the ARE biosolids-sand-sawdust product. Measurements of turfgrass color, quality and clipping yield will continue in addition to soil-atmosphere greenhouse-gas fluxes (i.e., CO2, CH4 and N2O) for the next several years. c