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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #131332
Title: SPATIAL AND TEMPORAL VARIABILITY OF SOIL NITRATE AND CORN YIELD: MULTIFRACTAL ANALYSIS

Author
item EGHBALL, BAHMAN
item SCHEPERS, JAMES
item NEGAHBAN, MEHRDAD - UNIV OF NE/LINCOLN NE
item SCHLEMMER, MICHAEL

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2003
Publication Date: 4/1/2003
Citation: EGHBALL, B., SCHEPERS, J.S., NEGAHBAN, M., SCHLEMMER, M.R. SPATIAL AND TEMPORAL VARIABILITY OF SOIL NITRATE AND CORN YIELD: MULTIFRACTAL ANALYSIS. AGRONOMY JOURNAL 95:339-346. 2003.

Interpretive Summary: High levels of residual soil nitrate can contaminate ground water by leaching through the soil. With the advent of precision agriculture technologies, it is now possible to apply different rates of fertilizer based on soil spatial variability within a field. An experiment was conducted on a 121 acres sprinkler-irrigated corn field in central Nebraska that included four N management practices of: uniform rate, variable rate, variable rate at 75% of recommended amount, and variable rate plus 10%. Variable rate at 75% decreased the amount of residual nitrate 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% did not increase corn yield or residual soil nitrate. Multifractal analysis, which is a useful method of characterizing the extent and pattern of spatial variability of soil parameters or crop yield, indicated no consistent pattern of spatial variability of soil nitrate for each treatment across four years. Corn grain yield spatial variability was much lower than that for soil nitrate. It seems that corn grain yield spatial variability is not significantly influenced by soil nitrate distribution indicating non-effectiveness of using soil nitrate 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 nitrate or corn grain yield as compared with uniform N. Multifractal analysis characterized and provided indication of patterns of spatial and temporal variability of soil nitrate and corn grain yield.

Technical 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 49 ha sprinkler-irrigated corn field in central Nebraska and included four N management practices of: 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 analysis, no consistent pattern of spatial variability of soil NO3-N was observed for each treatment across years. Corn grain yield spatial variability was much lower than that for soil NO3-N. Corn grain yield spatial variability was not significantly influenced by soil NO3-N distribution indicating non-effectiveness 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 was useful in characterizing the extent and pattern of spatial and temporal variability.