Compost Uses and Markets
Compost Uses and Markets: Expanding Opportunities
Hannah Heyman
Cornell University
Ithaca, New York
One of the top challenges facing urban landscape managers today is soil compaction from construction,heavy foot and vehicle traffic. Soil bulk density in urban areas is often so high that plants are unable to access the water and nutrients they require to live. This often means money is wasted on plants that will die after only a few years or on shipping in topsoil mined elsewhere. The third option is remediating the existing soil on site. Research conducted by Miles Schwartz Sax and Nina Bassuk in 2015 concluded that effective, long term compaction remediation can be achieved by incorporating generous amounts of compost (about 33% by volume) into existing compacted soil on site. This method, designated, “Scoop and Dump,” after the action of the backhoe doing the mixing, not only improvesbulk density and increases macroporosity over time, but also increases microbial activity and available water holding capacityin the soil.
My project is a continuation of this work to determine specifically what characteristics would define the ideal compost for the “Scoop and Dump” methodand compose a specification.Composts were collected from all over New York State from different producers (e.g. private companies, municipalities, farms, universities) and made from a variety of feedstocks (e.g. cow, horse and poultry manure, yard waste and food waste). Composts wereselected that covered a wide range of qualities like organic matter percentage, salinity and carbon to nitrogen ratio. Abioassay is being conducted with nine different composts at different concentrationsin the soil (0%, 33%, 50%, 100%). Additionally, leachate has been collected fromthe pots in our bioassayat regular intervals. From this leachate we are measuring the levels of soluble reactive phosphorous, nitrate and ammonium that are being lost from each compost mixture in order to determinethe risk of nutrient leaching forour final specification.
Urban soil has been given some much-deserved attention in recent months as a possible sink for greenhouse gases and as a first step to creating more livable cities overall. Using compost for on-site remediation will provide an opportunity for urban landscapers to save money and utilize locally sourced material. It will also provide a marketforcompostproducedfromthe recent mandateddiversionof organic wastein populated areas. A clear and comprehensivespecification will be a vital tool in bringing these industries together.