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Comparison of Diagnosis and Recommendation Integrated System and Nutrient Sufficiency Range for Corn

Dep. of Soil and Crop Sciences, Colorado State Univ., Fort Collins, CO 80523

M. J. Malakouti

Tarbiat Modarres Univ., Tehran, Iran

A. Ronaghi

Shiraz Univ., Shiraz, Iran

* Corresponding author ( psoltanp{at}shep.agsci.colostate.edu).

ABSTRACT

The diagnosis and recommendation integrated system (DRIS) is a potential method for interpreting plant foliar nutrient composition. The objective of our study was to compare DRIS with the nutrient sufficiency range (NSR) for corn (Zea mays L.). We used published standard DRIS norms and Colorado DRIS norms calculated from ear leaf composition at tasseling to silking of corn yielding 11 Mg grain ha^–1 or higher. Our NSR values are based on the minimum and maximum nutrient concentration values found in the literature. We changed the minimum value of 21 g kg^–1 for N to 26 g kg^–1. For identifying nutrient needs of corn, the NSR was superior to DRIS regardless of the DRIS norms used. Identified flaws of DRIS are: (i) very high levels of one nutrient can cause false relative deficiency (imbalance) diagnosis of other nutrients, and (ii) an optimal ratio between two nutrients produces maximum yields only when both nutrients are in their respective sufficiency ranges. We recommend use of the NSR technique in combination with a soil test to avoid the misdiagnosis of Zn and Cu deficiencies in corn when N is extremely deficient.

Contribution of the Dep. of Soil and Crop Sciences, Colorado State Univ., and Agric. Exp. Stn., Fort Collins, CO.

Received for publication November 5, 1993.