Plant Coverage and Growth in Urban Soils Amended with Organic Materials

Disturbed urban soils alongside roads and highways frequently fall short of organic matter (OM) and nutrients required for vegetation growth, and often worsen stormwater and erosion related issues. Vegetation in stormwater control systems can combat runoff pollutants and reduces the impact of rainfall intensity on the ground through interception. Rapid vegetative habitats can be achieved by incorporating compost or related products given their nutrient-rich profiles. A research study was conducted to find optimum ratios of soil and compost mixtures that can speed up the vegetative growth. Three sandy loam soils and one clayey soil, each amended separately with yard waste compost, food waste compost, turkey litter-based compost and biochar were chosen. Soil blends were prepared in triplicates at three application rates of OM (5, 7.5, and 10% by weight), totaling to 156 pots, and were tested for prairie-grass establishment. Biweekly plant coverage in each pot was estimated for “percent green” through image analysis. End-of-the-study measurements including plant biomass and height were also taken. Correlations among plant parameters (coverage, biomass, and height) and soil characteristics (OM, soluble salts, pH, nitrogen, and phosphorus contents) of the various blends are established. It is hypothesized that although the soil OM is increased by each amendment, the nitrogen species and the soluble salts content of the amendments are likely to dictate seed germination and plant growth. Specimens prepared at optimum soil-compost ratios based on the pot study will further be tested for water quality, vegetation, and soil hydraulic properties in larger mesocosms in the greenhouse.