Patent ID: 8451449

Claim:
A method for measuring organic matter content of soil, the method comprising: providing a sensor for measuring organic matter content of soil, the 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 configured to receive reflected light from the soil; (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; measuring organic matter content of soil with the sensor by determining reflectance at a plurality of different wavelengths of light and normalizing the reflectance to provide a normalized reflectance and determining the organic matter content of the soil using the normalized reflectance; varying application of an agricultural product at least partially based on the organic matter content of the soil; and wherein the measuring organic matter content of the soil and the varying application of the agricultural product being performed in real-time in a single pass.