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This article in SSSAJ

  1. Vol. 72 No. 4, p. 992-999
     
    Received: Nov 22, 2006
    Published: July, 2008


    * Corresponding author(s): Jacob.Bushong@ok.usda.gov
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doi:10.2136/sssaj2006.0401

Evaluation of Distillation and Diffusion Techniques for Estimating Hydrolyzable Amino Sugar-Nitrogen as a Means of Predicting Nitrogen Mineralization

  1. J. T. Bushong *a,
  2. T. L. Robertsb,
  3. W. J. Rossb,
  4. R. J. Normanb,
  5. N. A. Slatonb and
  6. C. E. Wilsonb
  1. a USDA-NRCS, 4900 Oklahoma Ave., Ste. 300, Woodward, OK 73801
    b Crop, Soil, and Environmental Sciences Dep., Univ. of Arkansas, 115 Plant Science Bldg., Fayetteville, AR 72701

Abstract

A rapid method to estimate soil N mineralization to improve N fertilizer recommendations has long been sought. Over the years, numerous methods to predict N mineralization have been proposed, but no one method has been widely accepted. Recently, researchers observed the concentration of hydrolyzable amino sugar-N in the soil correlated with crop N response. The objective of this study was to determine if developmental methods that quantify hydrolyzable amino sugar-N accurately predict N mineralization when compared to net-N mineralization by anaerobic incubation. Methods evaluated to predict hydrolyzable amino sugar-N were the Illinois soil nitrogen test (ISNT) by diffusion, and 2, 5, and 10 M NaOH direct steam distillation procedures. It was observed that the hydrolyzable amino sugar-N was a somewhat accurate predictor of N mineralization (R 2 = 0.38). However, when the hydrolyzable amino sugar-N concentrations were combined with the hydrolyzable NH4–N concentrations, the ability to predict N mineralization improved (R 2 = 0.61). Suggesting more labile soil organic N forms along with amino sugar-N are potentially mineralizable. Rapid analytical procedures like the ISNT diffusion method and the 2, 5, and 10 M NaOH direct steam distillation techniques accurately predicted hydrolyzable amino sugar-N as well as hydrolyzable (NH4 + amino sugar)-N. These methods also accurately predicted NH4–N mineralized after anaerobic incubation. It could be assumed that this predictability may increase when soils are analyzed based on soil management, geographic area, and crop rotation. Glucosamine recovery was significant ( >85%, P = 0.05) for both methods showing their ability to quantify amino sugar-N in the soil as well as estimate the amount of potentially mineralizable-N. Lastly, in soil-testing facilities where the ISNT is already implemented as a procedure, the much quicker and equally reliable 10 M NaOH distillation technique may be used to achieve near identical test values.

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