Diagnosis and Recommendation Integrated System (DRIS)

(Arnold Schumann, UF/IFAS, Citrus Research and Education Center) EMAIL: schumaw@ufl.edu

This web-based deployment of DRIS is designed for analysing leaf nutrient concentrations of Florida citrus. It has been optimized for Florida oranges (and related varieties) and the DRIS norms used for calculations were derived from a high-yielding 'Hamlin' orange grove in the central Florida Ridge region prior to the spread of greening disease (Huanglongbing, HLB). Since varieties like grapefruit have lower N requirements than oranges, the DRIS results for grapefruit may be less useful.

To use this tool, prepare an Excel file with your leaf nutrient data according to this template: CitrusDRIS-example.csv. The nutrients should appear in the following order and with these units (left to right): %N %P %K %Mg %Ca %S B (ppm) Zn (ppm) Mn (ppm) Fe (ppm) Cu (ppm). You should include the single line heading and a left column for sample identity, as shown. You can add many more line records to the file, as required. When done, save the file as a "comma-separated-values" (.csv) file. To start the analysis, follow the instructions below by uploading the data .csv file, and receiving the DRIS results in another .csv file, that you can read in Excel. If you encounter an error message, it means that the data file is incorrectly formatted, has missing values, or unexpected characters (e.g. an O instead of a 0). Correct the data file and retry.

DRIS results consist of a nutrient index for each nutrient, and an index for "dry mass" (DM). Indices range in value from negative (deficient or low) to near zero (optimum), to more positive (high or excessive). The magnitudes of the indices reflect the relative severity of the nutrient imbalance. An aggregate absolute value of all the indices is the Nutrient Balance Index (NBI), and a lower value indicates a more balanced tree nutrition. The diagnosis column lists the nutrients that are classified "deficient", "low", "high" or "excess" according to the SL253 IFAS publication. Moreover, the nutrients listed are ranked in order of decreasing severity (left to right). In the HLB era, this information is particularly useful since it can help prioritize the most appropriate corrective fertilization.

References:

Beaufils, E.R. 1973. Diagnosis and recommendation integrated system (DRIS). Soil Science Bull. No. 1, University of Natal, S. Africa

Walworth J.L., Sumner M.E. 1987. The Diagnosis and Recommendation Integrated System (DRIS). In: Stewart B.A. (eds) Advances in Soil Science vol 6. Springer, New York, NY

Schumann, A.W. 2009. Potential use of DRIS for leaf nutrient diagnosis in Florida Citrus. Citrus Industry 90:4, Ocala, FL, Southeast Agnet

Schumann, A.W. 2019. Critical leaf nutrient thresholds to diagnose deficiencies in HLB trees. Citrus Industry 100:4, Ocala, FL, Southeast Agnet

Nutrition of Florida Citrus Trees (SL253)

News Updates and Tips:

(4 April 2019): If you want to exclude a nutrient element from DRIS analysis, enter a zero (0) in the data file. For example, a lab may not provide sulfur (S) in the report. It is important to keep the format of the data file the same, so even if you do not have data for S, you should still include the S data column with all zeros.