Abstract

GARCIA, Gisela Vanesa; STUDDERT, Guillermo Alberto; NOE DOMINGO, Magalí  and  DOMINGUEZ, Germán Franco. Nitrógeno mineralizado en anaerobiosis: relación con sistemas de cultivo de agricultura continua. Cienc. suelo [online]. 2016, vol.34, n.1, pp.127-138. ISSN 1850-2067.

Nitrogen (N) mineralization during a short anaerobic incubation (NAN) could be used as a soil health indicator. To adjust its use, it is necessary to characterize and understand how it is affected by different management practices. For soils of the Southeast of the Buenos Aires Province we hypothesized that i) higher carbon (C) inputs through crop residues lead to lower NAN variations in the arable soil layer without difference between conventional tillage (CT) and no tillage (NT), and ii) the amount and quality of the preceding crop residue affects the NAN content. The aims of this work were: i) to evaluate the change in time of NAN at 0-20 cm under different crop sequences, CT and NT, and with and without N fertilization (NF), and ii) to analyze the effect of different crop residues on NAN at 0-20 cm. We determined NAN in stored soil samples taken from the 0-5 and 5-20 cm soil layers in two long term tillage system (TS) experiments (CT and NT): Experiment 1 with two levels of NF (with and without N), and Experiment 2: with three crop sequences (corn-corn-wheat, corn-soybean-wheat, soybean-soybean-wheat). Anaerobic N decreased along years under cropping at 0-5, 5-20 y 0-20 cm, under both TL and levels of NF. Only at 0-5 cm decreases were significantly different between TS (CT>NT). At 0-20 cm there were no differences in NAN decreases neither between levels of NF nor among crop sequences. Hence, different C inputs of different biomass productions did not lead to differential changes in NAN along cropping years. Different preceding crops did neither affect NAN contents. Nitrogen fertilization could have produced higher soil organic C mineralization since it decreases the soil system C/N ratio, masking the expected effects of crop residue characteristics on NAN. However, our results contribute to confirm the feasibility of using NAN as a soil health indicator.

Keywords : Potentially mineralizable nitrogen; Crop sequence; Tillage system; Nitrogen fertilization.

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