We report the development of a nondestructive experimental method that is capable of measuring changing solution contents and tracer salt concentrations in unsaturated soils. The method utilizes a dual-source, gamma-attenuation system. We develop and discuss a probable-error analysis of solution content and salt concentration determinations from the dual-source gamma system. Results from flux-controlled absorption of SrCl2 and NaI solution into two dry soils are presented. We observed substantial water movement apart from the liquid phase via vapor transport and adsorption mechanisms in the fine-textured silt loam, but not in the coarser sandy loam. Analyses of distributions of solution content and salt concentration during absorption provide insight into the complex interactions of multiphase transport mechanisms during solution movement in soils at low solution contents.