This article was developed with input from SITES Soil Technical Advisors.
Soil is the living skin of our planet: the foundation of all terrestrial life, regulator of our atmosphere, ultimate recycler of our waste and source of our water, food and materials. But as we’ve populated this planet and shaped it to our needs, we have often forgotten how essential soil is for our very survival.
Because soil formation is a slow process, it is critical to protect soil that is already healthy. For the SITES v2 rating system, this translates into conserving areas that are providing essential functions such as farmland, floodplains and wildlife habitat. That also means avoiding the disturbance or removal of other healthy soil found on-site, as well as importing soil from offsite greenfields or healthy farmland.
Soil health is defined as the continued capacity of soil to function as a vital living system within ecosystem and land-use boundaries; to sustain biological productivity; promote the quality of air and water environments; and maintain plant, animal and human health. Where and when soil health is compromised isn’t always readily apparent to many of us. That is why the SITES v2 rating system requires projects to conduct a thorough site assessment before design and construction begin with team members that have soil expertise.
Project teams can then understand existing soil conditions early on and use this to inform design. At this stage, it is also essential to understand the reference soil conditions to inform future restoration efforts needed for the soil management plan. A reference soil is a healthy native soil found on site. If none exist on a site, use undisturbed native soils within the site’s region that support appropriate native vegetation similar to those intended for the project site.
To ensure soil protection before and during construction of any SITES project, a Vegetation and Soils Protection Zone must be designated and then communicated to the project team and contractors. Specific strategies that minimize disturbance from construction activities and treatment plans for restoring soils are required in SITES. To ensure long-term site sustainability, the ongoing activities that protect the integrity of this essential ecological system must be outlined and communicated to site managers in a site maintenance plan.
Healthy soils are invaluable for supporting robust vegetation and providing a multitude of ecosystem services, such as filtering pollutants, sequestering carbon, reducing runoff, protecting water supply, controlling erosion and supporting wildlife. To ensure degraded soil has been restored, SITES projects must meet certain criteria that include soil organic matter, compaction, infiltration rates, biological function and chemical characteristics. Properly restoring soils with mature, stable compost is one of the best tools for building resilience in built landscapes. By increasing water storage, plant-rooting depth, temperature attenuation, plant vigor and hardiness are enhanced. The foundation of many green infrastructure and water conservation strategies also starts with healthy soils.
Remember, thoughtful soil management will also save money. By limiting site-grading activity, SITES-certified projects will reduce costs for construction machinery and transport of imported soils. Because healthy soils support healthy plant growth, there is also less need for pesticides, fertilizers and irrigation. If managed sustainably, this oft-overlooked yet vital and beneficial part of a landscape will foster resilience in communities that face uncertain climate changes, whether drought, flood, disease or northward-shifting growing zones. As Franklin D. Roosevelt once said, “A nation that destroys its soil, destroys itself.”