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This article in JEQ

  1. Vol. 31 No. 2, p. 671-681
    Received: Oct 10, 2000

    * Corresponding author(s): siva@savstate.edu
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Fate of Nitrate and Bromide in an Unsaturated Zone of a Sandy Soil under Citrus Production

  1. S. Paramasivam *a,
  2. A. K. Alvab,
  3. A. Faresc and
  4. K. S. Sajwand
  1. a Center for Marine, Environmental Sciences, and Biotechnology Research, P.O. Box 20600, Savannah State University, Savannah, GA 30404
    b USDA-ARS, Vegetable and Forage Crops Research Unit, 24106 N. Bunn Road, Prosser, WA 99350
    c University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850
    d CMESBR, Savannah State University Savannah, GA 30404


Understanding water and nutrient transport through the soil profile is important for efficient irrigation and nutrient management to minimize excess nutrient leaching below the rootzone. We applied four rates of N (28, 56, 84, and 112 kg N ha−1; equivalent to one-fourth of annual N rates being evaluated in this study for bearing citrus trees), and 80 kg Br ha−1 to a sandy Entisol with >25-yr-old citrus trees to (i) determine the temporal changes in NO3–N and Br distribution down the soil profile (2.4 m), and (ii) evaluate the measured concentrations of NO3–N and Br at various depths with those predicted by the Leaching Estimation and Chemistry Model (LEACHM). Nitrate N and Br concentrations approached the background levels by 42 and 214 d, respectively. Model-predicted volumetric water content and concentrations of NO3–N and Br at various depths within the entire soil profile were very close to measured values. The LEACHM data showed that 21 to 36% of applied fertilizer N leached below the root zone, while tree uptake accounted for 40 to 53%. Results of this study enhance our understanding of N dynamics in these sandy soils, and provide better evaluation of N and irrigation management to improve uptake efficiency, reduce N losses, and minimize the risk of ground water nitrate contamination from soils highly vulnerable to nutrient leaching.

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Copyright © 2002. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.31:671–681.