VIS-NIR - Spectrophotometer
Addressing Tomorrow’s Soil Challenges Today
What you can see about soil tells you something—for example darker soil has more organic matter. What you can’t see—but a near-infrared (NIR) spectrometer can—tells you
Spectrometers are being used in commercial agriculture today—in milling, forage, meat processing and more. But using them to measure soil properties is
relatively new. Researchers in laboratory settings have found visible and near-infrared reflectance (VIS-NIR) measurements of soil samples correlate to important soil
properties such as carbon and nitrogen.
Veris Spectrophotometers move these measurements out to the field, providing a platform for research into soil properties as
they vary within a field. Payments for soil carbon may soon represent an additional source of farm income—provided carbon can be measured accurately. Someday,
technology like this may be used to augment or replace traditional lab analyses for other soil constituents. All these possibilities require soil research—made
possible with tools like the Veris VIS-NIR Spectrophotometer.
About the Data
When light hits soil—molecules react—they vibrate. This vibration absorbs some of the light—how much light is either absorbed or reflected depends on what’s in the
soil. Soil with strong C-H, N-H, and O-H bonds absorb more light, which is why wet soil or soil with high organic matter looks darker—even to the naked eye. Spectral
data, especially in the near-infrared, is even more powerful. The reflectance signature of a spectrum can be used to measure carbon, nitrogen and water content of soil,
and relate to some soil chemical properties as well.
Veris Spectrometers measure soil reflectance from 350 to 2200 nanometers. This covers the visible portion of the spectrum and further into the near infrared than even
many bench-top spectrometers.
Every second, the Veris system records 20 spectra—each spectra contains 384 soil
measurements. It takes computing power, chemometric software, and calibration samples to turn all that spectral data into maps of the field.
But once that work is
completed, the results are striking—detailed soil maps, calibrated to precise levels of soil constituents.
Carbon sequestration in agricultural soils has the potential to reward growers, improve soil quality, and reduce CO2 emissions. Under a regulated offset-trading
program, in order for growers to receive payments for increasing soil carbon, baseline carbon levels would need to be measured. Later, verification would be required
in order to show carbon had been added. Yet carbon levels vary widely within most fields.
This makes it difficult to establish carbon levels with the degree of accuracy
needed for carbon payments. Results from Veris Technologies and independent research shows that VIS-NIR spectroscopy may play a large role in answering that challenge.
The power of VIS-NIR data goes beyond carbon. Research is on-going using spectral data to map a wide variety of soil properties, including calcium, magnesium,
potassium, pH, total nitrogen, and the Illinois Side-Dress Nitrogen test (ISNT).