The relationships between MR parameters and the content of water in packed samples of two soils

The relationship between the known water content and that determined using Magnetic Resonance (MR) methods was studied for samples of two soils packed to various dry bulk densities; four basic MR protocols were employed (single 90° pulse, inversion-recovery, Carr–Purcell–Meiboom–Gill (CPMG), and spin-echo (SE) pulse sequences). The soil types were chosen from a previously studied range of soils to represent both an “easy” (fine sand) and a “difficult” (coarse sandy loam) system for MR application. Whereas for the “easy” soil, the MR-detected water relates linearly to the soil water content as expected, for “difficult” soil the observed relationships are non-linear and depend on MR properties of soil water and MR protocols used.