Pedology, soil science

The aim of the lectures is to present the basic notions to describe, classify and characterize soils: their different constituents (minerals, clays, organic matter, living organisms), their physical properties (granulometry, texture, structure), chemical properties (clay-humus complex, CEC, oxidation-reduction), and biological properties (horizons and humus, root system, plant nutrition, role of bacteria, C/N ratio, pedofauna) We will study the factors of soil formation (climate, bedrock, living organisms, relief, time), the different processes of soil formation and evolution (weathering, humification, leaching, podzolization, pedoturbation, ferrallitization,...), the major soil classification systems, and the distribution of soils in the world. This scientific base will allow us to address current social issues concerning soils in the field of land management: their degradation (erosion, pollution, artificialization, compaction, etc.) and their restoration (depollution, phytoremediation, agroecology).

The field trip will allow to put into practice the notions seen in class.

Hourly volumes:

CM : 12h

TD : 9h

Field : 6h

The objective of this module is to establish a base of knowledge in pedology and soil science to be able to describe, classify, and characterize soils, their physical, chemical, and biological properties, as well as their formation and evolution in different environments.

Knowledge of general geology at the L1 level: IGN and geological mapping, external geodynamic cycle (alteration, erosion, transport, deposition).

• Continuous control
• Final examination

Synthetic description of the concepts covered in CM:

1. Introduction

• definitions of a soil (common, literary, scientific language)
• origin of a soil, the 3 phases of formation: alteration, incorporation of organic matter, transfer of elements
• examples of soil diversity (thickness, color, ...) on a global vs local scale

2. The bricks of the ground system

• mineral constituents (rock minerals to soil minerals, clay mineralogy)
• organic constituents (humus litter)
• living beings (bacteria, fungi, fauna); molecular ecology cultivable/visible diversity

3. Soil properties

a) Vision of a physicist

• 3 phases: solid, water, air
• grain size (sand, silt, clay)
• structure, porosity and air
• soil and water (water reserve)

b) Vision of a chemist

• clay-humus complex
• CEC, pH,
• redox

c) Vision of a naturalist

• Profile and horizons
• Humus type (O horizon)
• Color and stains, texture, structure, roots, coarse elements, ...

4. Soil and plant nutrition

• the root system
• plant nutrition: from deficiency to toxicity, total vs available elements
• role of microbes: catalysis of alteration, fate of OM, recycling, humification > C, N, P cycles
• soil symbioses (mycorrhizae, nitrogen fixers)
• role of the pedofauna (earthworms, ants, termites, ...): pedoturbation, upwelling of mineral elements, incorporation and transformation of organic matter
• in conclusion:
  -- functional feedback on humus types

-- soil and vegetation distribution (azonality, zonation)

5. Formation, evolution, classification and world distribution of soils

• the factors of soil formation: climate, bedrock, living organisms, relief, time (to age a soil)
• some processes of formation and evolution of a soil: alteration, humification, leaching, podzolization, pedoturbation, ferrallization, ...
• soil classification: diagnostic horizons; major classification systems (CPCS, Soil taxonomy, WRB)
• distribution of soils on a global (climate), national (bedrock) and local (relief) scale
• Mediterranean soils

6. Soil biodiversity and metal pollution. Phyto remediation. 

7. Soil biodiversity and hydrocarbon pollution (DNAPL and LNAPL). Phyto remediation

Synthetic description of the TD sessions and number of hours associated with each session

Six 1.5-hour class sessions will address current issues in soil and environmental sciences. The students will have to study scientific articles using the notions acquired in class. The articles used will be drawn from the following themes

Session 1: Description of a soil (color, texture, macrofauna, ...)

Session 2: Soils and the water cycle (runoff vs. infiltration, water storage, evapotranspiration)

Session 3 : Soil degradation - 1 : Erosion and flooding, artificialization, compaction, decrease in organic matter content

Session 4 : Soil degradation - 2 : Pollution of agricultural soils (pesticides : chlordecone, copper, ...) and industrial soils (mining sites, hydrocarbons, ...)

Session 5: Restoration of polluted soils (depollution, phytoremediation)

Session 6: Restoration of agricultural soils: alternatives to conventional agriculture (agroecology, agroforestry, permaculture, direct seeding, associated crops, legumes, terra preta)

Description of the themes/manipulations addressed during your field trip(s) and details of the destinations/sites

• Description of a typical Mediterranean soil profile
• Study of the spatial variability of soils along a toposequence as a function of topography and bedrock.

Basic knowledge of pedology and soil science

Recognition, characterization, and specific functions of the most common soils