What the smell of a soil can tell us about soil health

Farmers have long used their sense of smell to assess soil health, and ecologist Rosa Boone has found that soil odor can reveal valuable information about the microbial communities living in the soil. Boone discovered that by capturing and analyzing soil odors in the lab, scientists can gain insights into the types and numbers of fungi and bacteria present. Monitoring soil life is becoming increasingly important, particularly in light of upcoming soil monitoring guidelines.

Boone installed large tubes in 18 grasslands in the Ooijpolder, near Nijmegen, some of which were managed intensively using artificial fertilizer, while others were farmed more naturally. The odors from the soil were captured in smaller tubes connected to pumps, which then allowed researchers to analyze the captured odors in the lab.

The research showed that soil odors can reveal information about the fungi and bacteria living in the soil and the overall state of the microbial community. They identified 75 different odors, 16 of which were particularly good at indicating differences in management practices. Specifically, aldehydes—compounds primarily produced by fungi—were especially sensitive to changes in soil management. When management became more extensive, the presence of certain aldehydes increased, while others decreased.

Boone's findings suggest that odor sensing could offer a simpler and more practical method for monitoring soil life compared to traditional DNA analysis. By understanding the odor profiles of different soil management practices, farmers can make more informed decisions about their land use. A sensor that analyzes soil odors directly could provide a valuable tool for farmers seeking to manage their land sustainably and build healthier, more resilient soil ecosystems.