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Soil Science Society of America Journal Abstract -

Field Crop Recovery and Modeling of Nitrogen Mineralized from Labeled Sorghum Residues


This article in SSSAJ

  1. Vol. 55 No. 4, p. 1031-1037
    Received: Mar 2, 1990

    * Corresponding author(s):
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  1. M. F. Vigil ,
  2. D. E. Kissel and
  3. S. J. Smith
  1. USDA-ARS, 119 Keim Hall, East Campus, Univ. of Nebraska, Lincoln, NE 68583-0915
    Dep. of Agronomy, Plant Science Bldg., Univ. of Georgia, Athens, GA 30602
    USDA-ARS, Durant, OK 74702



Efficient use of fertilizer N requires an assessment of the N contribution from decomposing crop residues. The objectives of this study were to quantify and model the amount of mineralized N recovered by a growing crop from 15N-labeled sorghum (Sorghum bicolor [L.] Moench) residues of variable N concentration and composition. The residues were incorporated into the surface soil of field microplots. The microplots were double-cropped with sorghum and wheat (Triticum aestivum L.) for a 3-yr period. The 15N tag in the crop residue was used to distinguish between residue-derived N and that from soil organic matter. Between 4.5 and 25% of the residue N applied (36–83 kg N ha−1 was applied as crop residue N) was recovered by a sorghum crop 110 d after incorporation. This constituted 56 to 77% of the total N recovered during a 3-yr period. Accumulated N recovered over time was described by modified first-order models. Regression analysis indicated that 93% of the variability in N recovered by 110 d could be explained using the C/N ratio and acid-detergent fiber contents of the residues. Measurements of N mineralized, using the method described above, were compared with predicted N mineralized, using MINIMO (a subroutine of the CERES-Maize model). After adjusting MINIMO parameters using data collected 110 d after residue incorporation, the slope and intercept of a linear fit between measured and MINIMO-predicted N mineralized 1097 d after residue incorporation were not different from one and zero, respectively.

Research partially sponsored by Tennessee Valley Authority, Muscle Sholas, AL, and USDA-ARS in cooperation with the Dep. of Agronomy, Kansas State Univ., Manhattan. Contribution no. 90-385-J of the Kansas Agric. Exp. Stn.

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