Soil science

The aim of these lectures is to introduce the basic concepts needed to describe, classify and characterize soils: their various constituents (minerals, clays, organic matter, living organisms), their physical properties (granulometry, texture, structure), chemical properties (clay-humus complex, CEC, redox), and biological properties (horizons and humus, root systems, plant nutrition, role of bacteria, C/N ratio, peda-fauna). We will study the factors involved in soil formation (climate, bedrock, living organisms, relief, weather), the different processes involved in soil formation and evolution (weathering, humification, leaching, podzolization, pedoturbation, ferrallitization, etc.), the major soil classification systems, and the distribution of soils around the world. This scientific foundation will enable us to address current social issues concerning soils in TD: their degradation (erosion, pollution, artificialization, compaction, etc.) and their restoration (depollution, phytoremediation, agroecology).

The field trip will enable you to put into practice the concepts learned in class.

Hourly volumes:

CM: 12h

TD: 9h

Field : 6h

The aim of this module is to establish a knowledge base in pedology and soil science, so as 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.

L1-level knowledge of general geology: IGN and geological mapping, external geodynamic cycle (alteration, erosion, depositional transport).

• Continuous control
• Final examination

Synthetic description of the concepts covered in CM :

1. Introduction

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

2. The building blocks of the soil 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) A physicist's vision

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

b) A chemist's vision

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

c) A naturalist's vision

• 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 weathering, fate of OM, recycling, humification > C, N, P cycles
• soil symbioses (mycorrhizae, nitrogen fixers)
• role of pedofauna (earthworms, ants, termites, etc.): pedoturbation, upwelling of mineral elements, incorporation and transformation of organic matter
• in conclusion:
  -- functional feedback on humus types

-- soil and vegetation distribution (azonation, zonation)

5. Soil formation, evolution, classification and worldwide distribution

• factors in soil formation: climate, bedrock, living organisms, relief, time (soil age)
• some of the processes involved in soil formation and evolution: weathering, humification, leaching, podzolization, pedoturbation, ferrallitization, etc.
• soil classification: diagnostic horizons; major classification systems (CPCS, Référentiel pédologique, Soil taxonomy, WRB)
• soil distribution on global (climate), national (bedrock) and local (relief) scales
• Mediterranean soils

6. Soil biodiversity and metal pollution. Phyto remediation. 

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

Summary description of TD sessions and number of hours associated with each session

6 TD sessions of 1h30 each will deal with current issues in soil and environmental sciences. Students will be asked to study scientific articles, using the concepts acquired in class. The articles used will be drawn from the following themes:

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

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

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

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

Session 5: Restoring polluted soils (decontamination, phytoremediation)

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

Description of the themes/manips covered during your field trip(s) and details of 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