System for soil moisture monitoring

1. A method of measuring a soil characteristic during an operation in an agricultural field, comprising:

making a first soil reflectance measurement at a location in the field;

obtaining a second soil characteristic measurement, wherein said second soil characteristic measurement comprises a second soil reflectivity measurement at a different depth than said first soil reflectivity measurement;

correcting said first soil reflectance measurement based on said second soil characteristic measurement; and

estimating soil moisture at said location based on said corrected soil reflectance measurement.

2. The method of claim 1 , wherein said second soil characteristic measurement comprises an electrical conductivity measurement.

3. The method of claim 1 , wherein said second soil characteristic measurement comprises a pH measurement.

4. The method of claim 1 , wherein said second soil characteristic measurement comprises a second soil reflectivity measurement at a different wavelength than said first soil reflectivity measurement.

5. The method of claim 1 , further comprising:

accessing a soil property map;

determining a soil property at said location based on said soil property map; and

correcting an estimated soil property based on said soil property.

6. The method of claim 5 , wherein said soil property map comprises a soil type map.

7. A method of estimating soil moisture in a field, comprising:

obtaining a first soil reflectance measurement at a first depth at a first location in the field;

obtaining a second soil reflectance measurement at a second depth at a second location in the field;

determining a reflectance-based reflectance correction based on said second soil reflectance measurement; and

applying said reflectance-based reflectance correction to said first soil reflectance measurement to obtain a corrected first soil reflectance measurement; and

estimating moisture using said corrected first soil reflectance measurement.

8. The method of claim 7 , wherein said first soil reflectance measurement is carried out on a planter row unit, and wherein said second soil reflectance measurement is carried out on a separate row unit.

9. The method of claim 8 , wherein said separate row unit opens a trench having a different depth than the planter row unit, and wherein said separate row unit includes a reflectance sensor for measuring reflectance of soil in said trench.

10. The method of claim 7 , further comprising:

associating said estimated moisture with said first location using a GPS receiver; and mapping said estimated moisture.

11. A method of estimating soil moisture in a field, comprising:

obtaining a first soil reflectance measurement at a first wavelength at a first location;

obtaining a second soil reflectance measurement at a second wavelength at a second location near said first location;

obtaining a third soil reflectance measurement at said first wavelength at a third location near said first location, said third soil reflectance measurement being taken at a measurement depth, said measurement depth being different than said first soil reflectance measurement;

obtaining a fourth soil reflectance measurement at said second wavelength at a fourth location near said first location, said fourth soil reflectance measurement being taken at said measurement depth; and

estimating moisture based on said first soil reflectance measurement and said second soil reflectance measurement.

12. The method of claim 11 , further comprising:

determining a soil reflectance correction based on said third soil reflectance measurement and said fourth soil reflectance measurement; and applying said soil reflectance correction to said estimated moisture.