minirhizotron

A minirhizotron is a non-destructive imaging method used to observe roots in soil in situ. It involves inserting transparent tubes into the soil near the area of interest and using a camera, either manual or automated, to capture images of roots that appear on the inner wall of the tube. Images are collected periodically to monitor root growth, turnover, and phenology without excavating plants.

The basic workflow includes installing a clear tube at a chosen depth and in multiple positions, ensuring good soil–tube contact. A camera or endoscope is moved along the tube to photograph the roots over time. Image analysis software identifies roots and measures metrics such as root length density, root surface area, average diameter, and root mortality. Data enable calculation of growth rates and turnover and can be used to infer root activity under different treatments or environmental conditions.

Applications span agronomy, forestry, ecology, hydrology, and soil science. Minirhizotron data support studies of nutrient and water uptake, carbon allocation, root architecture, and responses to drought, nutrient deficiency, or management practices.

Advantages include high temporal resolution and the ability to monitor the same roots over time without destructive sampling. Limitations encompass potential disturbance during installation, a limited field of view, possible biases from tube geometry or soil conditions, and the need for careful calibration and image analysis to distinguish roots from soil artifacts.