Neutron Radiography for the Analysis of Plant–Soil Interactions

Abstract

Abstract Neutron radiography (NR) can be used to quantify the spatial distribution of water in the soil–plant system with high precision and good spatial resolution. This property of neutron imaging results from the high interaction probability of hydrogen nuclei with slow neutrons. If there is a sufficient difference between the water content of the soil and roots, neutron radiographs can reveal plant roots and show root development. NR is noninvasive, and the radiation dose needed to image plant roots in soil does not affect plant development. Quantification of the soil's water content often requires correction for neutron‐scattering artifacts. Root visibility is proportional to root thickness, and is inversely related to the width of the sample container and the water and organic matter contents of the ambient soil. Ideally, the soil should have low organic matter content and low water content but still permit the normal development of plant roots. Currently, the availability of neutron‐imaging facilities limits the widespread application of NR to soil and root studies. However, technological development and increased investment will result in NR becoming a standard method for some soil–plant analyses.