The 2013 Precision Ag Action Summit was held on January 21 & 22 in North Dakota. Newell Kitchen, USDA ARS gave a presentation on “In Field Sensors: Applications to Precision Agriculture”. Proximal soil sensing is the use of field based sensors to obtain signals from the soil when the sensor’s detector is in contact with or close to the soil. These PSS systems are commercially available.

Sensors Measure:
— Crop color – of the visible light spectrum, the chlorophyll in the chloroplasts absorbs the red and blue wavelengths and reflects the green. Nitrogen deficient corn has less chlorophyll and reflects less green. It looks yellowish-green to our eyes and is measureable by the sensors. This is an indicator of a plant’s “photosynthetic” health.
— Crop Biomass – The non-visible near infrared (NIR) wavelengths are reflected by crop foliage and absorbed by soil. Thurs, NIR energy can measure relative amounts of biomass. This is an indicator of a plants structural capacity to assimilate carbon.

Click here to view his full presentation.