Resumo

GENOVESE, María F; ECHEVERRIA, Hernán E; STUDDERT, Guillermo A  e  SAINZ ROZAS, Hernán. Amino-sugar nitrogen in soils: calibration and relationship with anaerobically incubated soil nitrogen. Cienc. suelo [online]. 2009, vol.27, n.2, pp.225-236. ISSN 1850-2067.

In the southeastern Buenos Aires province (Argentina), nitrogen (N) fertilizer recommendations for maize are based on soil nitrate contents. However, the organic fraction is a major component of soil N supply which should be estimated in order to improve NO₃ - testing reliability. The currently used method to estimate this supply is the anaerobically incubated soil N test (Nan). The main inconvenient about Nan is the relatively long incubation period required. The purpose of this work was to calibrate the Illinois soil nitrogen test (ISNT) for N-amino-sugar determination in southeastern Buenos Aires province, to evaluate its ability to identify different cropping systems and the relationship between ISNT and Nan. Diffusion units were designed and high N-glucosamine recovery percentages were reached, similar to those obtained with the original diffusion units. Recovery was greater when heating in enclosed griddles than heating in an incubator, thermostatic bath or oven. Similar ISNT values were obtained in our laboratory compared to standard samples from the University of Illinois. A weak relationship was determined between ISNT and years under cash-cropping, organic matter content and Nan. No differences in ISNT values were found between cropping systems (cash-crop years and tillage) and nitrogen rates. In summary, even though an adequate calibration for the ISNT could be achieved, the method was not able to identify different cropping systems. Even though further research is required to evaluate the ISNT as a means of detecting different N fertilization response sites, the results from this work are not promising for that purpose.

Palavras-chave : Organic nitrogen; Illinois soil nitrogen test; Nitrogen fertilization in corn; Potentially mineralizable nitrogen.

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