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Document Type

Dissertation - University Access Only

Award Date

1989

Degree Name

Doctor of Philosophy (PhD)

Department

Plant Science

First Advisor

Paul E. Fixen

Abstract

The Diagnosis Recommendation Integrated System (ORIS) is a method for plant analysis interpretation in soil fertility management of corn (Zea mays L.). A series of experiments were conducted to: 1) determine the accuracy of N status predictions by ORIS indices under water stress; 2) compare the standard and locally developed norms and the Critical Nutrient Levels in evaluating N status of irrigated corn; and 3) determine the influence of growth stage on DRIS indices using locally developed norms. A small data base of 600 observations was used to develop local norms for corn. A greenhouse study had seven levels of applied nitrogen (0, 1, 2, 3, 4, 5 and 6 g/plant) and three levels of water stress in a randomized complete block design. A three-year field experiment was conducted with seven levels of nitrogen in a randomized complete block design under irrigation. Two field experiments at different locations were conducted with seven levels of nitrogen and five levels of water stress in a randomized complete block design. Plant samples were collected at the four (V4), six (V6), twelve (V12) leaf stage; and at silking (R1) stage and analyzed for N, P, K, Ca, Mg, S, Mn, Zn and Cu. Water stress significantly influenced N indices; however the magnitude of the influence in the critical range near sufficiency was small enough to have limited agronomic importance. The Critical Nutrient Level approach predicted inadequate N across all treatments even when 46% more N was applied than required for maximum yield. Nitrogen indices calculated using the standard and local DRIS norms at optimum N were -3 and 0 respectively. Nitrogen indices for N check treatments using the standard and local norms were -11 and -10 respectively. Nitrogen status predictions at R1 more consistently related grain yield response to N than at V4, V6 and V12. The Nutrient Balance Index indicated greater variability in the standard norm than in the local norm.

Library of Congress Subject Headings

Corn -- Analysis
Nitrogen fertilizers -- South Dakota

Format

application/pdf

Publisher

South Dakota State University

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