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Sufficiency Level and Diagnosis and Recommendation Integrated System Approaches for Evaluating the Nitrogen Status of Corn
Author(s) -
Dara Syed T.,
Fixen P. E.,
Gelderman R. H.
Publication year - 1992
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1992.00021962008400060020x
Subject(s) - fertilizer , zea mays , mathematics , grain yield , nutrient , zoology , nitrogen , agronomy , field experiment , yield (engineering) , chemistry , biology , statistics , ecology , organic chemistry , materials science , metallurgy
An irrigated corn ( Zea mays L., cv. Pioneer 3732) N fertilizer field experiment was conducted for 3 yr to compare plant analysis interpretation of N status by the diagnosis and recommendation integrated system (DRIS) and sufficiency level (SL) methods. Preplant soil NO 3 ‐N was supplemented with ammonium nitrate to provide seven available N levels. Leaf samples were taken at the silking stage and analyzed for N, P, K, Ca, Mg, S, Mn, Zn, and Cu. Nutrient indices were calculated using published standard and locally‐developed (South Dakota) DRIS norms derived from 600 observations. At bighest grain yield, 11.86 Mg ha −1 , the average soil NO 3 ‐N level was 247 kg ha −1 over the 3‐yr test period, while check yields averaged 6.54 Mg ha −1 and required 68 kg N0 3 ‐N ha −1 . The SL approach (using a critical ear leaf N concentration of 27.6 g kg −1 ) diagnosed N as inadequate even when excess N was applied, indicating that the N sufficiency level for irrigated corn is inflated and needs to be readjusted to 25.2 g N kg −1 . Nitrogen indices calculated from the standard and local DRIS norms at 90% of maximum yield were −2 and 2, respectively. Regression of Nutrient Balance Indices against relative yield indicated greater variability in the standard norms than in the local norms. Our data suggest that the SL approach overestimated ear leaf N requirement, and that DRIS indices calculated using published standard norms were less useful than those from locally‐developed norms.