Stratification of the organic nitrogen stock in pampean soil profiles as a function of vegetation type and land use

M.R. MENDOZA, G. BERHONGARAY, R. ÁLVAREZ

Conferencia; 19th ISTRO Conference; 2012

Soil organic nitrogen stocks and profile stratification was determined under contrasting vegetation types and land uses in the Pampas. Samples from 386 sites widespread across the region were taken up to 1 m depth under five common scenarios: forest, uncropped sites under graminaceus vegetation, cropped soils under the pasture phase of a mixed rotation, cropped soils under the agricultural phase of the rotation and flooded lands. Nitrogen stocks were significantly different between treatments (forest>uncropped>pasture=cropped>flodded). In all cases 45-50 % of the nitrogen stored in 1 m was founded in the upper 25 cm of the soil. Nitrogen profiles could be fairly well fitted to a potential model and no significant differences were found between slopes of the vegetation-land use conditions. The stratification pattern of organic matter is not affected by these conditions in the Pampas.