Spatial and Temporal Variability of Soil Nitrate and Corn Yield: Multifractal Analysis

Authors

Bahman Eghball, University of Nebraska-Lincoln
James S. Schepers, University of Nebraska-LincolnFollow
Mehrdad Negahban, University of Nebraska-LincolnFollow
Michael R. Schlemmer, University of Nebraska-LincolnFollow

Date of this Version

3-1-2003

Comments

Published in Agron. J. 95:339–346 (2003). MARCH–APRIL 2003. Permission to use.

Abstract

High levels of residual soil NO₃–N can contaminate ground water by leaching through the soil. Our objective was to reduce the level and spatial variability of residual soil NO₃–N while maintaining optimum corn (Zea mays L.) production by variable rate N fertilizer application. The experiment was located on a 60-ha sprinkler-irrigated corn field in central Nebraska and included four N management prac- tices: uniform rate, variable rate (VRAT), variable rate at 75% of recommended amount (VRAT @ 75%), and variable rate plus 10% (VRAT + 10%). VRAT @ 75% decreased the amount of residual NO₃–N in the soil while maintaining similar grain yield to the other treatments, indicating over-application of N with treatments receiving the recommended rate. Increasing the recommended rate by 10% (VRAT + 10%) did not increase corn yield or residual soil NO₃–N. Based on multifractal spectrum, no consistent pattern of spatial variability of soil NO₃–N was observed for each treatment across years. Spatial variability in corn grain yield was much lower than that for soil NO₃–N, indicating noneffectiveness of using soil NO₃–N spatial distribution for variable rate N application unless some areas in the field are severely N deficient. Variable rate N application did not reduce variability of residual soil NO₃–N or corn grain yield as compared with uniform N. Multifractal analysis quantitatively characterized the extent and pattern of spatial and temporal variability in corn grain yield and residual soil nitrate.