Foliar diagnosis of soybean by dris

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Abstract
The Diagnosis and Recommendation Integrated System (DRIS) has proven useful in the interpretation of tissue elemental analyses for many crops, and research was undertaken to apply the same method for foliar diagnosis of soybean (Glycine max [L.] Merr.). Using a data bank in excess of 3500 tissue samples, reference values for evaluating the status of soybean with respect to N, P, K, Ca, Mg, Mn, Fe, Cu, Zn, Mo, B and Al were derived. DRIS diagnoses generally agreed with those obtained by the sufficiency range method. In addition, DRIS assessed the nutrient balance in plant tissue, and identified not only the most-limiting element, but the order in which other elements would likely become limiting. Further, DRIS was able to diagnose plant nutrient needs earlier in the life of the crop than the sufficiency range method (5 weeks compared to 10 weeks), which would allow remedial steps to be taken earlier. Treatments indicated by DRIS to be needed gave greater yield increases than those indicated by the sufficiency range approach. Geographic differences in DRIS norms were identified, and indicate that regional derivation of diagnostic values may be necessary.