The Use of Biosolid Amendments to Promote the Establishment and Persistence of Perennial Grasses Along Rhode Island Highways.

The roadside environment is a substantial portion of states’ managed lands and a critical element of their transportation infrastructures.  Low-growing perennial roadside grasses provide year-round erosion control, pollutant filtration, and aesthetic value within these environments.  Biosolids are rich in organic matter and plant-available nutrients, and can supply fertility to these grasses.  We measured the effects of a single application of 7 different soil amendments (5 stabilized biosolids [heat treated, alkaline stabilized, anaerobically digested, ash stabilized, composted], a biosolid/yard waste co-compost, and a yard waste compost) applied at three rates (48, 144, or 288 kg/N/ha for the biosolids, and 15%, 30% and 45% by volume [first 15 cm of soil] for the others), and an unamended soil control, on the establishment and persistence of a perennial cool-season grass mix. Experiments were conducted within a highway median in North Kingstown, RI with high disturbed, engineered soil beginning in September 2012..  After the first season, all amendments except yard waste compost significantly improved grass quality compared to the control at all rates.  For all amendments except the yard waste compost, the 144 kg/N/ha rate of application provided the best turf quality over the growing season.  Soil nitrate levels were significantly higher than the control for most amendments.  Only the biosolid co-compost and the composted biosolid amendment had significant differences in nitrate levels among application rates.  Soil nitrate level and product application rate were positively correlated with turf quality.  At the time of incorporation, only biosolid/yard waste compost showed significantly greater EC, while all rates showed significantly different pH than the control. By the spring after incorporation, any significant differences in either EC or pH between products or rates had disappeared.  One year after application, biosolid amendments, applied at any of the three rates tested, significantly improved roadside turf quality compared to unamended soil.

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See more from this Division: SSSA Division: Urban and Anthropogenic Soils
See more from this Session: Urban Soils: Functions, Evolution, and Services

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