Addressing DRIS (Diagnosis and Recommendation Integrated System) norms with potentially toxic elements for assessing the nutritional status of Eucalyptus amended with sewage sludge

Abstract

Background The Diagnosis and Recommendation Integrated System (DRIS) gave valuable indices of the nutritional status of Eucalyptus amended with sewage sludge (SS). Aims Our objective was to establish a DRIS norms and analytical method for Eucalyptus under SS application, by verifying in particular, the influence of potentially toxic elements (PTEs) on the nutritional and plant development. Method Data on mean annual increment, nutrient, and PTE concentration were obtained in an experiment at 22, 44, 54, and 76 months after planting Eucalyptus amended with SS. Results Our results indicated that DRIS can give valuable data on the nutritional balance indices, in which it was possible to verify that Ba was the most limiting element due to its excess present both in the low and high yielding subpopulations, ranging from 10 to 40% of the populations with excess of Ba. The nutritional diagnosis in agreement with the DRIS model ranged from 60 to 98% among the populations. When modeling the DRIS functions with inclusion of PTEs, a consistent evaluation of the Eucalyptus nutritional status was observed, which generated more reliable indices that were able to rank the limiting elements for the Eucalyptus productivity. Conclusion The new approach proved to be an effective tool for interpreting DRIS indices, by presenting reliable data when PTEs are included. Thus, the inclusion of PTEs in DRIS functions can provide valuable information, by determining which element can cause more damage to the plants. The need for specific norms for each region, plant age and sludge management are highlighted.