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Universidad de Chile (2011)

Modelación geoestadística del contenido de carbono orgánico del suelo entre las regiones de Valparaíso y de Los Ríos, Chile

Padarian Campusano, José Sergei

Titre : Modelación geoestadística del contenido de carbono orgánico del suelo entre las regiones de Valparaíso y de Los Ríos, Chile

Auteur : Padarian Campusano, José Sergei

Université de soutenance : Universidad de Chile

Grade : Ingeniero Agrónomo mención Manejo de Suelos y Aguas 2011

Résumé
Soil is one of the major reservoirs of carbon on Earth. Changes generated when moving from natural ecosystems to agroecosystems cause significant losses of the organic carbon (OC) accumulated on it, making necessary to have appropriate methods to evaluate its status. To achieve this, data of 440 soil series were used with the objective of modelling the spatial distribution of soil organic carbon (SOC) between Valparaíso and Los Ríos Regions (32o 9’ 2” – 40 o 40’ 52” lat. S and 0 – 600 m.a.s.l) using geostatistical techniques, in order to estimate the amount of OC stored in the first 25 cm. Two modelling lines were used, one with all the data (0,3 – 20% OC) and another that excluded 19 outliers (0,3 – 11,8% OC), using four methods : Ordinary Kriging, Co-Kriging, Ordinary Kriging with local semivariograms and Artificial Neural Network Residual Kriging. All methods showed good results (R2 > 0 ;67) after comparing the real values of SOC with those predicted by the models using cross-validation. Performance proved to be dependent on the modelling line, reinforcing the influence of outliers in the modelling process. Total SOC and average SOC per hectare in the study area was estimated at 873,58 43 Tg (1012 g) and 75,12 3,18 Mg ha-1 respectively.

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