Multiple sensor system and method for mapping soil in three dimensions

A method of mapping soil properties in a field in three dimensions, comprising:

• traversing a field with a reflectance module carried on a shank implement to collect optical measurements of soil properties in an X-Y plane at a first depth;
• processing said collected optical measurements to characterize the variability of the soil properties in the X-Y plane;
• identifying optimal sampling locations for profile investigations;
• and
• inserting a reflectance module carried on a probe implement vertically into the soil at said optimal sampling locations to collect optical measurements of soil properties in a −Z direction;
• wherein identifying optimal sampling locations comprises:
• compressing spectral data from the shank implement using principal component analysis;
• grouping the compressed spectral data into a plurality of clusters according to spectral properties;
• and
• selecting one location from each cluster for soil sampling;
• and
• wherein the step of compressing spectral data comprises using scores corresponding to the eigenvectors of a covariance matrix having the largest eigenvalues.

A method of mapping soil properties in a field in three dimensions, comprising:

• traversing a field with a reflectance module carried on a shank implement to collect optical measurements of soil properties in an X-Y plane at a first depth;
• processing said collected optical measurements to characterize the variability of the soil properties in the X-Y plane;
• using the collected optical measurements of soil properties in the X-Y plane to identify optimal sampling locations in the field for investigating a vertical soil profile;
• and
• inserting a reflectance module carried on a probe implement vertically into the soil profile in situ at said optimal sampling locations to collect additional optical measurements of soil properties in a −Z direction;
• wherein said vertical soil profile extends below said first depth, and wherein said reflectance module carried on the probe implement is inserted vertically into the soil profile in the −Z direction below said first depth while maintaining the probe implement stationary in an X-Y direction at said optimal sampling locations.