OPTICAL REAL-TIME SOIL SENSOR

• US 20130250305A1
• Filed: 05/23/2013
• Published: 09/26/2013
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Kyle H. Holland
• Original Assignee: Kyle H. Holland
• Inventors: Holland, Kyle H.
• Granted Patent: US 8,755,049 B2
• Time in Patent Office: Days
• US Class Current: 356/445
• CPC Class Codes: A01B 79/005 Precision agriculture
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/553 and using surface plasmons fluorescence excitation G01N21/648; enhanced Raman G01N21/658

Abstract

A light sensing apparatus for measuring the reflectance of sub surface soil in real-time while attached to a moving vehicle is disclosed. Reflectance measurements from the apparatus can be related to the organic matter content of the soil. The apparatus is housed in a corrosion resistant enclosure having field rebuildable wear surfaces. The wear surfaces help extend the life of the apparatus by isolating the apparatus'"'"'s main enclosure from soil abrasion. The wear surfaces also assist in conditioning the sensed soil surface by smoothing the surface prior to sensing. Signal conditioning circuitry in the apparatus is utilized to reject the influence of ambient light in the advent that the soil/apparatus interface opens. A digital processor or other “intelligent controller” is utilized in the apparatus to auto calibrate the apparatus in real-time and/or use predetermined tables or mathematical relationships in order to convert reflectance information into organic matter measurements.

Claims

1. A sensor for measuring organic matter content of soil, the sensor comprising:

a replaceable wear surface;

a corrosion resistant enclosure;

a light source for illuminating the soil with light;

at least one photo detector configured to receive reflected light from the soil;

a scratch resistant optical window in contact with the soil, wherein the optical window allows light from the light source to illuminate the soil and the reflected light emanating from the soil to reach the at least one photo detector.

2. The sensor of claim 1 wherein the scratch resistant optical window has a mohs hardness greater than six.

3. The sensor of claim 1 wherein the light source comprises at least one light emitting diode.

4. The sensor of claim 1 wherein the light source comprises at least one laser diode.

5. An agricultural implement comprising the sensor of claim 1.

6. A system for use in measuring organic matter content of soil, the system comprising:

a soil sensor comprising (a) a replaceable wear surface, (b) a corrosion resistant enclosure, (c) a light source for illuminating the soil with light, (d) at least one photo detector to receive reflected light from the soil, and (e) a scratch resistant optical window in contact with the soil, wherein the optical window allows light from the light source to illuminate the soil and the reflected light emanating from the soil to reach the at least one photo detector;

a phase detection circuit operatively connected to the at least one photo detector;

an analog-to-digital converter operatively connected to the phase detection circuit;

an intelligent control operatively connected to the analog-to-digital converter.

7. An agricultural implement comprising the system of claim 6.

8. The system of claim 6 wherein the intelligent control is programmed to normalize reflectance.

9. The system of claim 8 wherein the intelligent control is programmed to normalize reflectance using an equation having a denominator expressing a difference between reflectance at a first wavelength and reflectance at a second wavelength.