Soil Fertility and Nutrient management (1+1)

DIAGNOSIS AND RECOMMENDATION INTEGRATED SYSTEM (DRIS Method)

Concepts of DRIS
Concepts of DRIS: DRIS is a new approach to interpreting leaf or plant analysis which was first developed by “Beaufils” (1973) named as Diagnosis and Recommendation Integrated System (DRIS). It is a comprehensive system which identifies all the nutritional factors limiting crop production and increases the chances of obtaining high crop yields by improving fertilizer recommendations. The DRIS method uses “nutrient ratios” instead of absolute and or individual nutrient concentrations for interpretation of tissue analysis.
There is a set of optimum ratios among the nutrient elements (N/P or N/K or K/P) within a given plant for promoting the growth of the plant. DRIS mainly uses the “nutritional balancing” concept (Relationship among nutrients) in the detection of nutritional deficiencies or excess in the plant. Nutrient balance is a part of the proper interpretation of DRIS system because nutrient interactions to a larger extent determine crop yield and quality. The nutrient ratios are helpful to obtain special indexes which are called “Nutrient Index” or “Beaufills nutrient Indexes” (BNI).
The nutrient index values are used to rate the nutrients in order of their need by the plants analyzed. It also measures how far particular nutrients in the leaf or plant are from optimim are used in the calibration to classify yield factors in order of limiting importance. BNI are actually expression of the supplies of nutrients relative to each other. The concentration of each nutrient in the plant has an effect on the index value for each of the other nutrient. An abnormally high concentration of one or more nutrients will decrease the index values of other nutrients.
There will be positive and negative values for the nutrient index. The nutrients with positive indexes appeared to be in “excess” and nutrients with negative indexes appeared to be “deficient” in plants. DRIS indices can be calculated individually for each nutrient using the average nutrient ratio deviation obtained from the comparison with the optimum value of a given nutrient ratio. DRIS is a mathematical technique to apply plant analysis information (Nutrient concentration) for diagnosing the most limiting nutrient in a production system.
The evaluation is made by comparing the relative balance of nutrient content with norms established for that crop under high yield conditions. The evaluation is made by comparing the relative balance of nutrient content with norms established for that crop under high yield conditions.
To develop a DRIS for a crop, the following requirements must be met whenever possible.
1. All factors suspected of having effect on crop yield must be defined
2. The relationship between these factors and yield must be described
3. Calibrated norms must be established
4. Recommendations suited to particular sets of conditions and based on correct and judicious use of these norms must be continually refined.

Advantage
The importance of nutritional balance is taken in to account in deriving the norms and making diagnosis. It helps to quantify the nutrient balance in the plant.
The norms for nutrient content in leaves can be universally applied to the particular crop.
Diagnosis can be made over a wide range of stages of crop development.
The nutrient limiting yield through either excess or insufficient can be readily identified and arranged in order of their limiting importance for yield.
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