What is the Nirs technology on board combine harvesters used for?

Nirs technology is developed and installed on machines to respond to economic, environmental and societal issues. Like the near-infrared analyzers that shift on combine harvesters and whose role is to better understand the quality in the field. Gain in machine productivity but above all in the quality of the batches harvested to better promote marketing.

The spectrometer analyzes the grain quality directly in the elevator and stores the GPS position to map the results. (© Adobe Stock)

D e more and more manufacturers of combine harvesters provide equipment toanalyze the harvest live on the machine. On paper, the principle is quite simple. In reality, the technique seems a little more complex as the conditions for a near infrared analysis are demanding. Temperature, vibrations, dust, material flow, references… so many parameters that can influence the quality of the results provided by the installation.

To see more clearly how the technology works, let’s go back to the basics of the method. The Nirs (near infrared spectroscopy)Where near infrared spectroscopy, measurement and analysis of light reflection spectra in the wavelength range between 0.78 and 2.5 µm. In other words, the technique is based on the vibration of the molecules when they are excited by the infrared source.

Mathematical model to translate the spectrum into a criterion of interest

It is necessary to use a mathematical model in order to extract the criterion of interest from all the information present in the spectrum obtained. The constitution of a model is based on a calibration set, i.e. a set of samples for which the near infrared spectrum has been measured as well as the value of the criterion of interest by a reference method. .

In agriculture, it is often difficult to get an idea of ​​the quality of the harvest even when the harvest is in progress, to improve the settings if necessary. Also difficult tooptimize crop storage to improve further processing. Taking a sample to send to the lab can be time-consuming and tedious. To guarantee the reliability of the results, the conditions of use are rather demanding: controlled temperature and hygrometry… absence of vibrations, references for self-calibration for each sample measured… Hence the question that arises about the reliability of the data measured by the tool when it is installed under the hood of a harvester!

Corona Extreme at Zeiss

At Zeiss for example, a version called Corona Extreme is proposed. Whether it’s extremely hot, cold, or there are high levels of shock, vibration, dust or debris, the product promises to deliver true-to-scale curves from measured results. directly on the combine harvester. To achieve this, you must have the range of samples covering the widest possible variability in the parameter of interest. Care will be taken to ensure good representativeness of the samples between years, varieties, geographical origins. The samples are analytically characterized by the reference methods. If the first calibrations are feasible with a hundred samples, the validation of the calibration obtained requires a second set of independent data.

New Holland integrates its Nirs spectrometer on its CR range combines.New Holland integrates its Nirs spectrometer on its CR range combines. (©New Holland)

Once calibrated, the tool analyzes for example the oil content of the seeds but also the distribution of fatty acids. Dry matter rate, proteins, humidity… the device has the ability to analyze many criteria simply thanks to the crop flow that passes in front of the lens.

Harvest quality mapping

After having worked on the slurry tankers to find out the quantity of N, P and K elements spread, the brands focused on the forage harvesters with a view to characterizing the nutritional quality of fodder (example : John Deere Harvest Lab 3000). From now on, the technology is applied to combine harvesters, again to have a better overview of the quality of the harvest with a view to appropriate remuneration. The idea is, for example, to store in batches with similar qualities to improve the selling price and avoid diluting the superior qualities. Conversely, the data provided by the device can also make it possible to adjust the protein level of a batch of wheat, for example, in order to meet regulatory requirements.

At the house of new hollandthe system called Evo Nir was even paired with GPS. The electronics record the data by geolocating them to map the quality of the harvest. Annual calibrations can be performed remotely using an internet connection. The farmer can also modulate the dose of fertilizer. For the time being, the manufacturer is adapting the technology to its high-density press and is even considering other variations.

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