Abstract
The Diagnosis and Recommendation Integrated System (DRIS) allows the interpretation of results of leaf analysis through relationships among nutrients, instead of the absolute and isolated concentration of each one, as it is used by the criterion of sufficiency range. The objective was to evaluate three procedures of calculation of DRIS indices, and to verify the efficiency of DRIS as interpretation method for the results of Brachiaria decumbens (Signal grass). The study was developed with the results of six experiments carried out in a greenhouse at Piracicaba, SP, with nutrient solution. Concentrations of N, P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn were used in the samples of recently expanded leaf laminae of the grass. The validation of the DRIS method used results from an experiment with nitrogen and sulfur rates applied to the same grass from the Mundo Novo farm, Brotas, SP. DRIS indices were calculated according to two criteria to choose the ratio order of nutrients (F value and R value) and three ways to calculate the nutrient functions (methods of Beaufils, Jones, and Elwali & Gascho). Nutritional Balance Index (NBI), calculated according to the generated norms, presented negative and significant correlation coefficients with the productivity in the combinations of methods tested and DRIS methods proposed by Beaufils, Jones and Elwali & Gascho were efficient in detecting concentrations that show nutrients deficiency or excess.
Highlights
The Diagnosis and Recommendation Integrated System (DRIS) is a method of nutritional diagnosis for crops based on the calculation of an index for each nutrient
For the nutritional diagnosis using the DRIS method, the methodology proposed by Wadt (1996) was used, as well as three classes established from the DRIS Indices of the nutrient (INut.) and the Average Nutritional Balance Index (NBIa), assuming: Defficient = INut. < 0 and Adequate = |INut.| ≤ NBIa
It is expected that the lower the NBI, the better the nutritional balance and the greater the crop productivity
Summary
The Diagnosis and Recommendation Integrated System (DRIS) is a method of nutritional diagnosis for crops based on the calculation of an index for each nutrient. The objective in this paper was to evaluate three procedures for calculating DRIS indices, as well as to verify the efficiency of DRIS as a method for improving the interpretation of analysis results of recently expanded leaf laminae of Signal grass in relation to the method of nutritional diagnosis based on the criterion of sufficiency range.
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