Real-time soil organic matter sensor

An apparatus for attachment to a vehicle for sensing the organic matter content of soil at a soil scene as the vehicle moves the apparatus through the soil, the soil scene being part of a particular landscape, the soil of the landscape falling within the particular class of soil, the apparatus comprising:

• a probe having a housing, a light source, a light sensor, and means for processing an output signal from the light sensor to determine the organic matter content of the soil scene;
• means for mounting the light source and the light sensor in the housing so that light from the light source is directed onto the soil scene and such that the light sensor senses light from the light source that is reflected from the soil scene;
• means for attaching the housing to the vehicle such that the probe is moved through the soil as the vehicle moves and the soil scene is beneath the surface of the soil;
• the light sensor sensing the light from the light source that is reflected from the soil scene and producing an output signal related to the organic matter content of the soil at the soil scene;
• means for coupling the light sensor to the processing means;
• the processing means having an equation related to characteristics of the particular class of soil, the equation having at least one parameter related to characteristics of the soil of the particular landscape within the particular class of soil, the processing means processing the output signal from the light sensor by solving the equation for the organic matter content of the soil at the soil scene using the output signal as an input to the equation;
• and
• the housing including means for preparing the soil scene before it is observed by the light sensor to obtain a generally uniform surface.

A method of determining the organic matter content of soil at a soil scene comprising the steps of

• directing a source of light onto the soil scene;
• sensing the light reflected from the soil scene;
• selecting one of a plurality of equations for a particular class of soils which includes the soil at the soil scene;
• processing the sensed light to determine the organic matter content of the soil at the soil scene based upon the magnitude of the sensed light and the selected equation which correlates the magnitude of the sensed light to the organic matter content of the soil.

An apparatus for attachment to a vehicle for sensing the organic matter content of soil at a soil scene, comprising:

• a probe having a housing, a light source and a light sensor;
• the light sensor including a photodiode and the light source including a plurality of red light emitting diodes arranged circularly around the photodiode;
• means for mounting the light source and the light sensor in the housing so that light from the light source is directed onto the soil scene and such that the light sensor senses light from the light source that is reflected from the soil scene;
• and
• means for attaching the housing to the vehicle wherein the vehicle moves the probe through the soil and the soil scene against which the light from the light source is directed is beneath the surface of the soil;
• the light sensed by the light sensor being indicative of the organic matter content of the soil scene.