As unusual as it might sound, the Underpants Degradation Test offers a surprisingly powerful indicator of soil biological activity.
Led by Teagasc and the VistaMilk Research Ireland Centre, GroundTruth aims to boost public engagement in environmental science by involving farmers, students and communities in hands-on research. Among its tools is this quirky yet effective method, burying 100% cotton underwear in the soil.
Why underpants? The test is based on a simple principle – healthy soils are abundant with life. Microbes and other organisms in biologically active soils quickly break down organic material like cotton. By burying a pair of cotton underpants in different soil types and examining their decomposition after several weeks, participants get a direct, visual insight into how biologically active their soil is.
The more degraded the fabric, the healthier and more biologically vibrant the soil. Conversely, intact underwear suggests low biological activity, potentially pointing to issues like compaction, poor organic matter, or disrupted soil ecosystems.
GroundTruth encourages this test as part of a broader soil literacy effort, alongside earthworm counts, soil structure assessments (VESS) and flower-insect biodiversity observations. These tests give participants the tools to better understand the invisible world beneath their feet and why it matters.
As data from across the country rolls in, it will be analysed by biodiversity experts at Teagasc and VistaMilk, contributing to national efforts to monitor and manage soil health. Findings will be shared during Soil Health Week (22–27 September) and submitted to the National Biodiversity Data Centre.
For further insights on the Underpants Degradation Test watch the below video:
Soil Health Week 2025
From Monday, 22 September to Friday, 26 September, Teagasc will host Soil Health Week, a dedicated weeklong initiative designed to support and inspire farmers, students and the general public with the latest insights, innovations, and practical guidance on soil health. From informative podcasts and live “Ask the Expert” webinar, to farm walks, expert-led lectures, and engaging talks, the week offers a packed schedule aimed at deepening understanding and sparking conversation around sustainable soil management.