The determination of the Beaufils ranges consists in optimal ranges of nutrients for the assessment of leaf nutrients (Table 3 and 4). This method consists of determining the ranges by means of statistical models of the relationship between leaf concentrations and DRIS index, and, Beaufils (1973) found that from the optimal values of DRIS index were determined intervals of standard deviation of DRIS index for each range of nutritional assessment. Following this criterion, the range that would include the nutrients that would be deficiency was below — 4/3 standard deviation (s); deficiency-prone between — 4/3 to 2/3 s; sufficient between — 2/3 to 2/3 s and a excess-prone 2/3 to 4/3 s; excessive greater than 4/3 s (Table 3).

Thus, it creates the Beaufils ranges, which can be used to interpretate the nutrient concentration in chemical analysis of leaves (Table 3 and 4). As such use, recommended for the specific regions where they were certain, because if extrapolated to other region, it is expected that the results do not follow a favorable response.

2. Conclusion

The DRIS developed by Beaufils (1973) had among its objectives, to correct the problem of correlation with the sampling time of the plant nutrients, and using dual ratio that promote the relationship among. Hence, improving efficacy of plant nutritional diagnosis allows the determination of the evaluation of the nutritional balance.

With the advent of Diagnose and Recommendation Integrated System (DRIS) by Beaufils (1973), researchers were setting to this system of nutritional diagnosis in order to increase their efficiency. However, evolution has brought a number of possibilities for calculation of DRIS’ norms and functions, that are needed to be tested to determine the best combination of methodology.

The use of DRIS is still being widely disseminated in the world, DRIS brings results consistently good in assessing the nutritional status of plants, showing the nutritional balance, a fact which is not observed with traditional systems (sufficiency range and critical level).