Resumen

DI GERONIMO, Paula Florencia; VIDELA, Cecilia del Carmen  y  LACLAU, Pablo. Organic C and N distribution in granulometric fractions of soils from grasslands, agriculture and forestation. Cienc. suelo [online]. 2018, vol.36, n.1, pp.11-22. ISSN 1850-2067.

Changes in land use modify soil C and N dynamics. Our objectives were (1) to study C and N variations in the organic matter and its granulometric fractions (MOP and MOAM), and (2) to evaluate how these variations affect the potentially mineralizable N (Nan) under different land uses. Analyzed land uses were: grassland (PN), agriculture (AGR), forestation with pines (MP), and thinned strips in MP: secondary grassland (PS). We determined the lowest total organic carbon (COT), total N (Nt), C and N in granulometric fractions, and Nan values at AGR, evidencing soil degradation. The COT values at MP and PS (63,3 and 53,5 g kg^-1, respectively) were greater than at PN (50,4 g kg^-1 soil), due to an increase in C associated with minerals (C-MOAM). We observed more Nt, C-MOP and N-MOP at PN than at MP and P. This explained the fact that Nan was 100 mg Kg^-1 greater at PN than at MP and PS. The N-MOP was the variable that best explained Nan variability (R2 = 0,859). The C and N distribution in the MO and its fractions reflected changes in land use, but it is necessary to better study C and N dynamics under forest vegetation.

Palabras clave : MOP; MOAM; C/N relation.

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