Electromagnetic Induction As a Tool for Mapping Coarse Fragments in Texas.

Soils containing coarse fragments are known to have high spatial and temporal variability of soil water content. Presence of coarse fragments complicates measurement of soil properties such as water content and can often lead to over or underestimated values if the effect of coarse fragments is neglected. Mapping coarse fragments would have applications in understanding the soil-water dynamics of these soils and calibration procedures for surface water content sensors. On a gravelly clay loam with woody encroachment, several electromagnetic induction (EMI) surveys were conducted at different water contents near San Marcos, Texas. Water content, bulk density, and coarse fragments were measured and compared with the EMI surveys. Preliminary results indicate a response in EMI surveys to coarse fragments, and a strong spatial correlation between coarse fragments and vegetation cover. Final results are pending further research.