PLANT ANALYSIS INTERPRETATION BASED ON A NEW INDEX - DEVIATION FROM OPTIMUM PERCENTAGE (DOP)

The objective of the present work is to introduce a new index (DOP: Deviation from Optimum Percentage), as an alternative methodology for plant mineral analysis interpretation. The DOP index is calculated for each of the analyzed elements by applying the following general formula: DOP = [(C x 100)/Cref] - 100, where C is the nutrient concentration in the sample to assess and Cref is the optimal nutrient concentration used as a reference value. The calculations used to obtain the DOP index can be easily implemented in a microcomputer. An optimum nutritional situation for any element is defined by a DOP index equal to zero. The DOP index permits to know the nutrient limitation order in a given sample, giving information similar to that obtained with the DRIS method. Furthermore, the DOP indexes indicate wether a element is in defect (negative indexes) or excess (positive indexes). For comparison, the DOP index has been applied, together with other traditional methods including the DRIS approach, to a new nutrient database from a peach tree study and to other available databases from the scientific literature. Other examples are shown indicating the different behavior of DRIS and DOP method when nutrient contents change.