Crops’ potential in your hands

Greenseeker | NDVI scanning goes handheld to help producers make decisions on the go

WOODSTOCK, Ont. — Green-seeker’s machinery-mounted crop analysis system has been released in a handheld version.

The new tool puts normalized difference vegetation index (NDVI) referencing in the palm of a producer’s or agronomist’s hand.

Portable meters have been available to measure plant vigour, vegetative cover and chlorophyll levels by recording the amount of near infrared light and red light that they reflect and absorb, but due to price and durability issues they haven’t been widely used in field crop production.

For more than a decade, Trimble’s Green-seeker was strictly a hardwired tool, typically mounted on sprayers or fertilizer spreaders.

Those units trigger herbicide applications by sensing weeds or fertilizer when the need for additional nitrogen to maximize yield is found.

The tools don’t specifically tell a producer what to do about a crop that might be missing its mid-season yield potential, but they do provide a way to measure unfulfilled potential and point to either shortages of nutrients or pest issues that are interfering with growth.

Barry Raymer of the Farm Office in Tavistock, Ont., got his hands on one of the first handheld units in Canada last week.

“Mostly they are an educational tool,” the crop consultant and Trimble dealer said while attending Canada’s Outdoor Farm Show in Guelph.

“Farmers who do their own crop scouting and want a portable reference tool should find them useful. For producers who have staff or family that are tasked with scouting, it is a way of coming back with some numbers that indicate there is a need to do some further investigation if there are issues.”

Agronomy consultant Greg Kitchen of Premier Equipment in Elmira, Ont., said he sees the portable tool as way to put an empirical measurement to what his eye “might or might not detect.”

“It should give you a pretty good idea of what the crop needs before it really suffers or gets to a point where you can’t do anything about it,” he said.


“But it’s a scouting tool that you need to develop some practices around. I’m looking forward to having one in the truck.”

Matt Grant of Trimble said making it portable and reducing the unit price to $500 means that a lot of producers and agronomists can make use of a technology that used to cost considerably more.

“The Greenseeker is a really rugged technology, so putting that into a handheld device can give a farmer something he can carry that aids in that decision making on the go,” Grant said.

NDVI is a measure of plant health. The greater the amount of chlorophyll in the leaves, the more sunlight in the red region of the light spectrum will be absorbed.

As well, a plant’s leaf cell structure, the spongy mesophyll, reflects near infrared light. The healthier the plant, the more red light it absorbs and near infra red it reflects.

The higher the NDVI numbers, the healthier the plant. The Green-seeker measures these light quantities and provides a NDVI reading using a formula.

The portable tool can read the crop canopy at a single point, but for greater accuracy the trigger can be held and the user can walk with the tool to obtain a cumulative reading of an area.

Grant said the unit works best 24 to 48 inches from the ground or crop.

“It has a spot where you can attach a plumb bob to keep you a consistent height,” he said.

The unit reads an area 10 inches wide at 24 inches from the ground and 20 inches wide at 48 inches from the ground.


Larger areas and longer scans that are created by walking with the machines create more accurate readings because more plants are measured.

“There will be a lot of different strategies for their use. Farmers are pretty creative about how they use stuff. And this is a reference tool,” said Grant.

One application might be to have a high nitrogen reference strip in a field where plants will have access to more than sufficient amounts of the nutrient. The rest of the field receives a standard amount of nitrogen.

As the crop develops, the producer can measure the difference between the high nitrogen strip and the rest of the field.

He can then use Trimble’s reference algorithm charts to determine whether additional applications of fertilizer will improve the crop’s yield and by approximately how much based on a targeted yield.

It doesn’t record or geo-reference its readings, so a notebook, smart phone or handheld computer is still going to be necessary to record the readings.

Grant said his company will soon release a new version of its free smart phone software that will allow input of the data. That can be used on its own or sent wirelessly to the Trimble’s Formworks desktop agronomy management software.

The company provides charts and calculations for most crops, including the usual spring and winter wheat, barley, canola, triticale and dryland and irrigated corn.

Powered by a replaceable cellphone-type battery, the unit will run for two days on a full charge and is charged through a mini-USB cable.