SIDNEY, Mont. – How can the GreenSeeker hand-held sensor be used to make better nutrient management decisions at farms and ranches?

Tanner Stevens, field rep at the USDA-ARS lab in Sidney, demonstrated how to use GreenSeeker, an easy-to-use measurement device designed to assess the health, or the vigor, of a plant at field days.

Trimble and other manufacturers developed various models over the years.

The optical sensor must be positioned over the crop, and is designed to get a numerical reading, “to assess what is going on with the crop,” Stevens said.

Stevens explained he pulls a trigger, which starts the device.

“The sensor emits brief bursts of red and infrared light, measuring the amount of each type of light that is reflected back from the plant,” Stevens said, pointing out how the light flashed and a number appeared.

GreenSeeker allows a producer to calculate the Normalized Difference Vegetation Index, or NDVI, a vegetable index, measuring from 0 to 0.99 on the LCD screen. The higher the reading, the healthier the plant.

“If plants are under stress, such as in drought, the NDVI is lower as compared to unstressed crop,” he said. “By gathering several readings from plants throughout a field, producers can better determine the overall health and needs of the crop.”

Readings taken with the GreenSeeker can be used to make objective decisions regarding the amount of fertilizer to be applied to a crop, resulting in a more efficient use of inputs.

Producers could also find out the potential yield of a crop, and use it for zoning a field.

“If you know which areas are more production, those might need more N than other areas where you could save N,” Stevens said.

More efficient usage of N can also help with maintaining soil pH.

The GreenSeeker can also be used to indicate basic nutrient response, crop condition, yield potential, stress, biomass, leaf area, herbicide efficiency, pest impact and to monitor changing field conditions (crop and plant) during the growing season.

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