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This article in AJ

  1. Vol. 100 No. 4, p. 1020-1025
     
    Received: Feb 27, 2007


    * Corresponding author(s): fertibalc@balcarce.inta.gov.ar
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doi:10.2134/agronj2007.0077

Contribution of Anaerobically Mineralized Nitrogen to the Reliability of Planting or Presidedress Soil Nitrogen Test in Maize

  1. Hernán Sainz Rozas *a,
  2. Pablo A. Calviñob,
  3. Hernán E. Echeverríac,
  4. Pablo A. Barbierid and
  5. Miguel Redolattib
  1. a Estación Experimental Agropecuaria, INTA, Balcarce, Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
    b Bolivar 710, Tandil city, Buenos Aires, Argentina
    c Estación Experimental Agropecuaria, INTA, Balcarce, and Fac. Ciencias Agrarias (UNMP), Unidad Integrada, Balcarce, C.C. 276 (7620) Balcarce, Buenos Aires, Argentina
    d Estación Experimental Agropecuaria INTA, Balcarce, Buenos Aires, Argentina

Abstract

The objective of this work was to evaluate if soil mineralizable N under anaerobic conditions (Nan) improves the reliability of preplant soil nitrate test (PPNT) and presidedress soil nitrate test (PSNT). The study was conducted under no-tillage (NT) in the southeastern Buenos Aires province, Argentina, in 26 site-years. In some site-years treatments were fixed N rates (0, 70, 140, and 210 kg ha−1 or 0, 60, 120, 180, and 240 kg ha−1) applied at planting, whereas in others site-years N rates were determined by adding N to lead targets of N supply up to 120, 160, and 200 kg N ha−1 When sites were not separated by Nan, relative yield (RY) correlated with PPNT (r 2 = 0.37) and reliability of PPNT did not increase when sites were separated by low (<48 mg kg−1) and high Nan (>48 mg kg−1). A high relationship between RY and PSNT (r 2 = 0.56) was determined. However, when sites were separated by Nan, reliability of PSNT increased, mainly for sites with low Nan (r 2 = 0.68 and 0.44 for sites with low and high Nan, respectively). Critical PSNT values for 94% of RY were 75 and 90 kg N ha−1 for sites with high and low Nan, respectively. The results show that PSNT was a better diagnostic method for maize (Zea mays L.) than PPNT. However, the separation of sites by its N mineralization capacity increased reliability of PSNT by indicating a lower N requirement to reach 94% of RY, decreasing the risk of overfertilization, an important feature from economical and environmental standpoints.

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Copyright © 2008. American Society of AgronomyCopyright © 2008 by the American Society of Agronomy