Abstract: The present disclosure discloses a method for evaluating the nutritional status in plants, using visible-to-shortwave (VIS-SWIR) infrared reflectance spectroscopy of carbohydrates, particularly in almond trees. The method comprises obtaining a dry plant sample (i.e. leaves, branches and roots), digesting and grinding it to a powder, capturing predetermined spectral data of the ground plant sample, correlating said spectral data to predetermined materials and evaluating said nitrogen status of said plants according to predetermined multivariate statistical models. The data obtained from this method facilitates crop management and fertilization by providing the nitrogen status of the plants based on non-structural carbohydrates.

Abstract: A method of measuring element concentration in plant leaves comprises steps of: (a) gathering leaves of plants to be tested; (b) conditioning specimens of said leaves; (c) obtaining raw count-per-second XRF datasets of said specimens; (d) obtaining raw NIR datasets of said specimens; (e) obtaining raw analytical datasets; and (f) assessing concentrations of minerals within said specimens on the basis of said count-per-second XRF, NIR and analytical datasets. The aforesaid method further comprises steps of obtaining white reference radiance datasets and normalizing said raw NIR datasets on the basis thereof and providing NIR reflectance datasets.