En los últimos 150 años la humanidad incrementó la emisión de CO2, acelerando el calentamiento atmosférico global. La retención de carbono orgánico en los suelos (COS) mitiga dicho efecto y contribuye a mejorar la calidad del recurso. Los factores que regulan el COS pueden analizarse desde la perspectiva pedológica utilizando la ecuación de estado, que postula que modificaciones en los factores formadores (FF) producirán variaciones en los procesos pedogenéticos (PP) y cambios en las propiedades de los suelos. Los objetivos de la presente tesis fueron: i) Cuantificar los niveles de COS en regiones geográficas homogéneas y establecer su variación a través del paisaje; ii) Evaluar efectos por cambio en la condición climática sobre COS en suelos de granulométrica homogénea y similar relieve; iii) Establecer efectos sobre COS por cambios en los materiales parentales (MP) en condiciones análogas de relieve y clima; iiii) Determinar la acción antrópica por diferentes usos de la tierra e intensidades de uso agrícola. El área de estudio se ubicó en la Pampa Austral, abarcando 110 perfiles en los que se evaluaron 15 variables de sitio, morfológicas, físicas, químicas, biológicas y taxonómicas. Los resultados indicaron que el relieve fue el FF de mayor influencia sobre COS y que la incidencia del resto de los FF varió en función del mismo. Las llanuras de inundación presentaron los más altos contenidos de COS, superando a los valles interserranos y paleocauces, seguidos de planos normales o cóncavos, lomadas y laderas. El análisis jerárquico permitió una mayor comprensión de los FF, PP y mejor predicción del COS. El clima ejerce una acción positiva afectada por el relieve y el MP. En suelos de sedimentos loéssicos y en planos normales la precipitación media anual y la profundidad efectiva en conjunto explicaron un 49 % de la variabilidad del COS (P <0,01). Los MP ejercieron influencia regional sobre COS (r= 0,28, P <0,05, N= 110), aún con la interferencia de otros FF. Los sedimentos aluviales presentaron elevados niveles de COS (171 Mg ha-1), seguido por los sedimentos loéssicos (108 Mg ha-1) y sedimentos eólicos recientes (81 Mg ha-1). El uso produjo cambios en el carbono de 0-25 cm y en el carbono orgánico de 0-1 m. El uso forestal mostró los más altos contenidos de CO0-25 en todos los materiales parentales. La intensidad del uso impactó de manera diferencial sobre el COS en función de la granulometría. Bajo agricultura extractiva los suelos de texturas gruesas presentaron mermas del 60 % en CO. La inclusión de siembra directa y pasturas puede lograr retenciones de 0,7 Mg ha-1 año-1. Se ha demostrado que el relieve es el FF que regula los niveles de COS de la región, modificando el balance de los PP. COS mostró respuesta a la intensidad de la melanización. Los PP modificaron su relación en función de la profundidad efectiva: los suelos someros presentaron melanización intensa, mientras que los suelos profundos redujeron la misma a favor de la iluviación o la alcalinización. La clasificación taxonómica a nivel de familia reflejó claramente los principales FF y PP que ocurren en la Pampa Austral. Las taxas de suelos segregadas y los contenidos de carbono orgánico presentaron una fuerte asociación, lográndose a partir de ellas una mayor certidumbre en la explicación de la variabilidad del COS. Palabras claves: Carbono orgánico del suelo, factores formadores, procesos pedogenéticos, usos del suelo, retención de carbono, Pampa Austral. / Human activity increased CO2 emissions in the last 150 years, accelerating global atmospheric warming. Soil organic carbon storage (SOC) mitigates warming and helps to improving soil quality. Factors that regulate SOC can be analyzed from the pedological approach using the equation of state factors, says changes in the soil forming factors (FF) and their interactions produce variations in pedogenic processes (PP) and changes in soil properties. The objectives of this thesis were: i) measure SOC levels in homogeneous geographic region and analyzing variability across landscape; ii) measure effects of change climatic condition of SOC in soils with similar parent material (PM) and relief; iii) quantify effects on SOC for changes in PM to similar conditions of relief and climate; iiii) determine antropic effects by different land uses and management practices. The study area was located in Austral Pampa, using 110 soil profiles in which 15 site, morphological, physical, chemical, biological and taxonomic variables were evaluated. Results indicated that relief was the most influential FF on SOC, and the incidence of the remaining FF varied according to the same. Flood-plains showed the highest SOC level, followed by saw-valleys and paleo-valleys, normal flats, concave flats, hills and slopes. Hierarchical analysis showed greater understanding of the FF, PP and better prediction of SOC. The climate has a positive effect modified by relief and PM. In soils of loess sediments located in normal flats annual average rainfall and the effective depth explained 49% of the SOC variability (P <0.01). PM presented a regional effect on COS (r = 0.28, P <0.05, N= 110), despite the interference from other FF. Alluvial sediments showed high COS levels (171 Mg ha-1) followed by loess sediments (108 Mg ha-1) and recent aeolian sediments (81 Mg ha-1). Land use produced changes in 0-25 cm and 0-1 m organic carbon. Forest use showed the highest organic carbon content in 0-25 cm on all parent materials. Tillage systems and management practices impacted differently on the SOC in relation to soil texture. Intensive farming in coarse soils showed declines of 60% in CO. No-tillage and pasture showed retention rates of 0.7 Mg ha-1 yr-1. Relief is the main FF regulating COS levels in the region and the balance of the PP, and responded to intensity of melanization. PP changed their relationship as a function of effective depth: shallow soils showed intense melanization, whereas deep soils reduced melanization in favor of illuviation or alkalinization. Soil Taxonomy family level reflected clearly the main FF and PP occurring in the Austral Pampa. Soil taxas segregated and organic carbon contents showed a strong association, improving the explanation of SOC variability. Keywords: Soil organic carbon, soil forming factors, pedogenetic processes, land use, carbon retention, Austral Pampa.

Sand Pits have great potential to restore via spontaneous succession. There are not many studies of the development of soils in sand pits; therefore, this work focuses on the development of soil properties in sand pits comparing technically reclaimed sites and sites with primary succession. 120 samples were collected at fourteen sand pits in South Bohemia and selected soil properties were assessed. The surveyed plot were grouped according to age, and the successional and technically reclaimed sites were distinguished. The results were evaluated by analysis of variation and regression analysis. The differences in soil bulk density, pH, thickness of soil organic horizon, Cox, N and C/N ratio between reclaimed and spontaneously restored sites of different age were analysed. The bulk density and pH decrease significantly on successional sites; however, the reclaimed sites do not show signifiant differences. Organic horizon thickness increases with age on both types of sites.Cox, N and C/N ratio do not show significant influence age. Lower values of Cox, N and C/N were measured in initial stages of succession. On the reclaimed sites there is almost no change in values of Cox, N and C/N ratio, because of the occurrence of nutrient-richer substráte used during technical reclamation. Keywords: soil...

Changes brought about by chemical and physical weathering were investigated in a chronosequence of terrace soils near Reefton, New Zealand. The parent materials of the soil, which ranged in age from about 1000 to over 130,000 years were outwash gravels, sands and silts derived from granite (dominant) and indurated sandstone. Variations in pH, organic matter, particle size, cation exchange properties, total Mg, Al, Si, K, Ca, Fe and Ti, poorly-ordered and organic-complexed forms of Al and Fe, and mineralogy caused by increasing duration of weathering and by short range, short term variations in the intensity of the biotic factor were determined. It was concluded that the younger soils represented dynamic systems in which alternative weathering cycles could replace each other as the growth, death and eventual disappearance of individual red beech trees caused localised fluctuations in pH. It was further concluded that these processes would lead ultimately to the formation of gley podzols as are now found on the two oldest surfaces p and that podzolisation preceded gleying. Attempts were made to determine if minerals of the plumbogummite group were responsible for the high proportion of soil phosphate from these soils that, on fractionation, appeared in the residual P fraction. It was found that attempts to concentrate these minerals by prolonged digestion with HF resulted in their solution, and in precipitation of complex fluorides that yielded diffraction spacings that have been mistaken for minerals of the plumbogummite group.