DIFFERENTIAL RESPONSE OF CORN HYBRIDS TO APPLIED NITROGEN (EFFICIENCY UPTAKE)

STEPHEN EARL HAWKINS, Purdue University

Abstract

Efficient use of fertilizer inputs in corn production is a major concern with corn producers in keeping costs to a minimum. Selecting an efficient system to utilize nitrogen fertilizers would address application methods, formulation, tillage, climate, and cropping history. Another factor is the variation between genotypic response of corn hybrids to nitrogen. This study was designed to examine six hybrids at eight nitrogen treatments while previous studies have utilized two or three regimes. Three of the N treatments used in this experiment were split into a preplant treatment with 67 kg N ha('-1) of the total amount applied just prior to tasseling. Grain and stover yield and N content was examined to determine overall nitrogen use efficiency and uptake and utilization characteristics during the growing season. The overall efficiency of nitrogen use declined as nitrogen rates were increased in all hybrids, but two hybrids exhibited the inability to translate increased rates of applied nitrogen into increased grain yield. Differences in nitrogen uptake and utilization characteristics existing between corn hybrids may not be pronounced enough with existing genotypes to manage except in high nitrogen loss situations. A second study was conducted with twenty hybrids to attempt to evaluate their responsiveness to applied N and split applications of N. The hybrids used in general responded to increasing N rates at both locations. Split applications of N did not result in increased yields at either location. In summary, this work has shown that some differences do exist between commercial hybrids currently being grown as to their response to applied N.

Degree

Ph.D.

Subject Area

Agronomy

COinS