Mineralizable nitrogen in anaerobiosis and its relationship with different organic n pools

GREGORUTTI, V.C.; NOVELLI, L.E.; MELCHIORI, R.J.M.; ORMAECHEA, V.; CAVIGLIA, O.P.

Ciencia del Suelo

ASOCIACIÓN ARGENTINA DE LA CIENCIA DEL SUELO

Lugar: Buenos Aires; Año: 2014 vol. 32 p. 41 - 51

0326-3169

Diagnosis of soil nitrogen fertility usually does not include the contribution of soil organic pools. Mineralisable nitrogen in 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 affects 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 others experiments with different crop sequences in 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 the contents of NT, NOP and Nan. In addition, positive relationships were found between the Nan and NT content (R2 = 0.65; P < 0.001) and NOP (R2= 0.85, P < 0.001), which are attributable 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 improve as compared to the evaluation in the bulk soil sample.