But success or failure of NIR analysis depends on proper calibration of the machine. Calibration samples must be collected and analyzed chemically. These samples must represent all the hay to be analyzed. Quality of the chemical analysis used for calibration also is critical to the NIR analysis. The NIR analysis will be no more accurate than the chemical data it s based on.
Accuracy decreases when samples fall outside the calibration range.
Seldom will one set of calibration samples suffice for all factors measured. New Mexico alfalfa growers have developed a reputation for producing high quality alfalfa. This reputation has helped develop a high demand for their hay. When hay buyers purchase over a long time from the same source, they assume a certain quality, so no hay grading is necessary. But if the buyer wants to know about the chemical qualities of a lot of hay, then whatever hay grading system is used must provide results that truly represent the feeding value of the lot of hay.