Resumo

GREGORUTTI, Viviana Carolina et al. Nitrógeno incubado en anaerobiosis y su relación con el nitrogeno orgánico en diferentes fracciones. Cienc. suelo [online]. 2014, vol.32, n.1, pp.41-51. ISSN 1850-2067.

Diagnosis of soil nitrogen fertility does not usually include the contribution of soil organic pools. Mineralisable nitrogen under anaerobiosis (Nan) and other labile N fractions may be useful to predict the mineralized soil nitrogen pool and to improve the diagnosis of soil nitrogen fertility, although management practices may affect these pools. The aims of our study were to: i) evaluate the effect of long-term nitrogen fertilization and crop sequences on organic nitrogen in the soil particulate fraction (NOP) and Nan, and ii) evaluate the relationship between Nan, total nitrogen (NT) and NOP. In a long-term continuous maize experiment, and two other experiments with different crop sequences and two soil types, NT, NOP and Nan were determined in the bulk soil samples and on macroaggregates in two depths. The sources of variation evaluated in these experiments did not show differences in NT, NOP and Nan contents. In addition, positive relationships were found between Nan and NT contents (R² = 0.65; P < 0.001) and between Nan and NOP (R²= 0.85, P < 0.001), which are attributed to the variation in depths and contrasting sites. Moreover, we found a strong association between Nan in bulk soil sample and Nan in macroaggregates (P < 0.001), evidencing that a high proportion of Nan was allocated in the macroaggregates. The determination of Nan and NOP in soil macroaggregates did not present advantages compared to the evaluation in the bulk soil sample.

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