For Thomas Woltz, Soil Is the Most Important Surface There Is

The founding principal of Nelson Byrd Woltz Landscape Architects discusses how soil can advance both ecological and social justice.

Surfaces of all kinds are top of mind these days, so we decided to look at all aspects of them, in these articles, from A to Z. Thinking of surfaces less as a product category and more as a framework, we use them as a lens for understanding the designed environment. Surfaces are sites of materials innovation, outlets for technology and science, and embodiments of standards around health and sustainability, as well as a medium for artists and researchers to explore political questions.


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For the land bridge at Memorial Park in Houston, Nelson Byrd Woltz Landscape Architects’ design process began with an in-depth analysis of the cultural and ecological history of the soil, both of which informed the process by which the drought stricken area is being readied for regreening. Courtesy Nelson Byrd Woltz Landscape Architects

Soil is a gigantic living system in and of itself. It has incredible complexity. It is one of the most important things we should be caring for in a sustainable future for the planet. A healthy soil is 50 percent water and air. When that’s combined with organic and mineral material, a microbiome of living organisms starts to flourish and do different kinds of jobs. It conveys nutrients, holds water, and forms communication networks between plants. We step on soil all the time without thinking about how rich and sophisticated it is.

Our approach to soil has two distinct categories with a lot of overlap. One is the ecological state of the soil: We do soil tests, borings, drainage, and compaction to evaluate its health. Then we bridge the ecosystem we find with the ecosystem we aspire to. Soil is one of the biggest factors in carbon sequestration, for example, because it holds carbon in the form of the roots and the decay when a tree dies. The soil locks up that carbon until you till it and open it, when the soil is aerated.

The second category is the soil’s traces of the cultural landscape that human beings leave behind through dialogue with land. With current conversations about equity, diversity, and inclusion, we must acknowledge, reveal, and discuss the hidden stories of land. The landscape of the native ownership of North America is almost eradicated. There are traces, mounds, but also dark periods of history. The idea of honoring the cultural history of soil has been lost.

I am so excited to be a landscape architect right now because we have the opportunity to bridge ecological justice and social justice with the design field of landscape architecture. In all of our projects, our mission is to use research to uncover the fragile cultures and ecologies that shape our world, and to steward them toward a more resilient future.

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The landscaping at Hudson Yards, which Nelson Byrd Woltz worked on. Courtesy Nelson Byrd Woltz Landscape Architects

Memorial Park in Houston, for example, was a project born out of tragedy. Houston suffered four years of epic drought and about 80 percent of the tree canopy died in this park, which is twice the size of Central Park—it looked like Armageddon. We did one year of public consultation, one year of master planning, got unanimous city council approval, and then were hired to do implementation. In the process of working with the community, we had 3,300 people weigh in on the plan. And we ended up gathering a community-based volunteer working group to continue to review the plan as it developed.

Dr. John Jacob is a soil scientist who joined this committee. Looking at the project’s soil excavations, maybe six to eight feet deep, he discovered parallel layers of ash. This led us to understand that this land had been managed with fire as open prairie by the Karankawa people, who first inhabited this part of the Gulf Coast of Texas. Under the management of Native American people, this ecosystem survived thousands of years of drought, floods, and hurricanes. The clue to maintaining 1,461 acres in the 21st century is not high-tech alternatives; it’s looking at land management strategies from thousands of years ago.

Now, the ecology of the soil: The Memorial Park Conservancy has built a massive composting operation—grinding dead trees from the devastated forest—that’s been cooking since 2017. It has biology, it has nutrients, it is rich. Carolyn White, an environmental planner from the City of Houston, and her team at the Conservancy are conducting test trials for cover crops using the compost and seeing how the soil biology reacts. So as we’re doing the design work, they’re researching the healthiest soil for this massive undertaking. We’re getting scoops of soil from the Nash Prairie just outside Houston and using that soil microbiome to inoculate the compost. The plants and the seeds are also coming from the Gulf Coast area, so they’re native seeds. It’s a social, cultural, and ecological system. For too long in our culture we have had a one-way relationship with soil: We extract its nutrients and its minerals, but we have broken the tradition of giving back. We need to enter a relationship of exchange with soil. We must give to it. We must be respectful and generous.

You may also enjoy “Welcome to the Agrihood

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Categories: Landscape