Wildfire Smoke and Apple Orchard Soils
Current project, Duncan Environmental Lab
Wildfire smoke deposits combustion-derived nitrogen onto soil and leaf surfaces, and this material carries an isotopic signature distinct from the nitrogen already present in orchard soils. By tracking this isotopic signature over time, we can distinguish smoke-derived nitrogen inputs from background soil nitrogen, and follow how quickly that smoke-derived material moves into the soil profile, is taken up by trees, or is lost from the system. We are also tracking general soil metal concentrations as part of our broader soil health monitoring.
Shortly after the 2026 wildfires near Spokane County, WA, the lab collected an initial round of soil and leaf samples from apple orchards in the area, establishing a baseline for post-fire smoke deposition. Because wildfire activity in the region is expected to continue in future years, we plan to keep sampling these orchards across multiple growing seasons, both to track how smoke-derived nitrogen already in the system moves through the soil and into trees, and to capture the effects of any additional smoke events as they occur.
This work aims to help orchard growers and land managers in fire-prone regions understand the longer-term soil and crop health consequences of smoke exposure, beyond the immediate, visible effects of a fire season.
Learn more about the lab and how to get involved on the lab page.