Edafología: Soil Science and Soil Properties

Edafología: Ciencia del suelo

• The science studies the soil in its genesis, morphology, classification, and use.
• Studies the interrelation between soil and the environment.
• An applied science.

Soil as a Complex System

• A system has interrelated elements that interact with each other.
• Complex means consisting of many elements and relations.
• The solid subsystem includes minerals and organic matter.
• The liquid subsystem is the soil solution.
• The gaseous subsystem is the soil air.
• The biological subsystem includes living things in the soil.
• Independent variables: climate, relief, parental material, time, biological activity.
• Dependent variables: properties of the soil (physical, chemical, biological).
• Jenny's equation represents soil as a function of climate, organisms, relief, parental material and time.

Soil as a Natural Resource

• Natural resource that is non-renewable on a human scale.
• Functions as support for plant growth.
• A regulator of biogeochemical cycles.
• A habitat for soil fauna.
• A construction material.
• An archive of environmental history.
• Threats include erosion, contamination, sealing, loss of organic matter, salinization and compaction.

Horizon

• Layer of soil approximately parallel to the ground surface.
• Characteristics of the soil are produced by the soil formation processes.
• The O horizon is the organic horizon.
• The A horizon is the mineral horizon with an accumulation of organic matter.
• The E horizon is the washed horizon (eluvial).
• The B horizon is the accumulation horizon (illuvial).
• The C horizon is the altered parental material.
• The R horizon is bedrock.

Profile

• Vertical section of the soil shows the sequence of horizons.
• Study of the profile is important.
• Tells the history and evolution of the soil.
• Base for the classification and mapping of soils.

Soil-Plant Relationship

• Soil provides physical support, water, nutrients, and air to plants.
• Plants influence the soil through organic matter input.
• Plants influence through extraction of water and nutrients.
• Plants influence through protection against erosion.
• Plants influence through alteration of the microclimate.

Texture

• Proportion of mineral particles of different sizes in the soil.
• Sand: 2 - 0.05 mm
• Silt: 0.05 - 0.002 mm
• Clay: < 0.002 mm
• Influences water retention capacity, aeration, drainage, fertility.

Structure

• Soil structure describes how soil particles are aggregated.
• Granular structure exists
• Crumb structure exists
• Block structure exists
• Prismatic structure exists
• Laminated structure exists
• Influences aeration, drainage, porosity, resistance to erosion.

Colour

• Property of the soil that is determined visually.
• Munsell notation describes hue, value and chroma
• Hue: tone (red, yellow, green, blue, purple).
• Value: clarity (0 = black, 10 = white).
• Chroma: intensity (0 = neutral, 10 = bright).
• Indicates the content of organic matter, iron oxides, degree of humidity.

Density

• Bulk density (Da): Mass of dry soil per unit of total volume.
• Real density (Dr): Mass of dry soil per unit volume of solid particles.
• Porosity: Volume of pores per unit total volume.
• Influences aeration, drainage, water retention capacity, resistance to penetration of roots.

Water in the Soil

• Hygroscopic water adheres to soil particles.
• Capillary is retained in the micropores by surface tension.
• Gravitational water moves freely by gravity.
• Field capacity: Amount of water retained by the soil after draining the gravitational water.
• Permanent wilting point: Water content at which plants cannot extract more water from the soil.
• Available water: Difference between the field capacity and the permanent wilting point.

Air in the Soil

• Composition: greater concentration of CO2 and less O2 than in the atmosphere.
• Necessary for the respiration of the roots and the microorganisms.
• Influenced by texture, structure, water content, temperature.

Soil Temperature

• Influenced by solar radiation, vegetation cover, colour, water, texture, structure.
• Influences biological activity, germination of seeds, and root growth.

Soil Reaction (pH)

• Measure of the acidity or alkalinity of the soil.
• Scale: 0-14 (7 = neutral, < 7 = acidic, > 7 = alkaline).
• Influences the availability of nutrients, microbial activity, and solubility of heavy metals.

Salinity

• Concentration of soluble salts in the soil.
• Measured in electrical conductivity (dS/m).
• Problems: difficult for plants to absorb water, toxicity by specific ions.
• Causes: Irrigation with saline water, capillary rise of saline water, excessive fertilization.

Organic matter

• Set of organic substances present in the soil.
• Fresh organic matter consists of poorly decomposed plant and animal remains.
• Humus is the stable organic substance, resulting from the transformation of fresh organic matter.
• Improves structure, increases water retention capacity, provides nutrients, and favors biological activity.

Essential Nutrients

• Macronutrients: N, P, K, Ca, Mg, S.
• Micronutrients: Fe, Mn, Zn, Cu, B, Mo, Cl.
• Necessary for the growth and development of plants.
• Availability depends on pH, organic matter content, interaction with other nutrients.

Soil Pollution

• Organic pollutants: pesticides, hydrocarbons, solvents.
• Inorganic pollutants: heavy metals, nitrates, phosphates.
• Sources: industrial, agricultural, and urban activities.
• Effects: toxicity to plants, groundwater contamination, accumulation in the food chain.

Soil Erosion

• Process of detachment and transport of soil particles due to water or wind action.
• Water erosion: surface, in ruts, in gullies.
• Wind erosion: deflation, abrasion.
• Influenced by climate, relief, vegetation, and land use.
• Consequences: loss of fertility, sedimentation of dams, water pollution.

Classification of Soils

• Grouping soils according to their properties and genesis.
• Used systems like the Soil Taxonomy (USDA) and the World Reference Base for Soil Resources (WRB).
• Soil orders, suborders, large groups, subgroups, families, and series can be categorized.
• Diagnostic horizons and physical, chemical, mineralogical properties are used

Stock Exchanges

• NYSE, NASDAQ, BATS, Direct Edge, Archipelago. are examples of stock exchange venues
• ECNs are electronic communication networks
• ATSs are Alternative Trading Systems

Order Types

• Market Order: Execute immediately at the best available price.
• Limit Order: Execute only at a specified price or better.
• Stop Order: Becomes a market order when a specified price (stop price) is reached.
• Stop-Limit Order: Becomes a limit order when a specified price is reached.
• Hidden Order/Iceberg Order: Only a portion of the order is displayed.
• Fill or Kill (FOK): Execute the entire order immediately or cancel it.
• Immediate or Cancel (IOC): Execute any portion of the order immediately and cancel the rest.
• All or None (AON): Execute the entire order at once or not at all.

Algorithmic Trading

• Uses computer programs to automatically execute trades based on a set of predefined rules.
• Algorithmic Trading, Automated Trading, Black-Box Trading, or Algo-Trading
• Reduces transaction costs.
• Improves execution speed.
• Increases trading capacity.
• Automates hedging strategies.
• Backtesting.

Order Book

• Electronic list of buy and sell orders for a specific security, organized by price level.
• Bids are buy orders
• Asks are sell orders
• Market depth: The number of shares available at each price level.

VWAP and TWAP

• Volume Weighted Average Price (VWAP) is the average price a stock traded at over a specified period, weighted by volume.
• Time Weighted Average Price (TWAP) is the average price of a stock over a specified period.

VWAP Strategy

• Execute trades to match the VWAP of the day.
• Goal: Minimize market impact.
• How: Trade proportionally to the historical volume pattern.
• Pros: Simple to implement, reduces market impact.
• Cons: May not be optimal in all market conditions.

TWAP Strategy

• Execute trades evenly over a specified period.
• Goal: Achieve the average price over the period.
• How: Divide the order into equal-sized chunks and execute them at regular intervals.
• Pros: Simple to implement.
• Cons: Ignores volume and market conditions.

Implementation Shortfall

• The difference between the actual execution price and the decision price.
• Goal: Minimize the difference between the expected price and the actual price.
• How: Consider both market impact and opportunity cost.
• Pros: Aims for optimal execution.
• Cons: More complex to implement.

Market Impact

• The effect of a trader's actions on the price of an asset.
• Large orders move the market price.
• Factors Affecting Market Impact: order size, market liquidity, order urgency, market condition
• Reducing Market Impact is done by splitting orders, using hidden orders, trading during liquid hours, and choosing the right order type.

High-Frequency Trading (HFT)

• A type of algorithmic trading characterized by high speed, high turnover, and high order-to-trade ratios.
• Latency: The time it takes for a signal to travel from one point to another.
• Characteristics of HFT: colocation, direct market access, market making, statistical arbitrage.

Vocabulaire des probabilités

Expérience aléatoire

• An experiment whose possible outcomes are known, but the specific outcome cannot be predicted.
• Ex: Rolling a 6-sided die, spinning a lottery wheel

Univers

• The set of all possible outcomes of a random experiment.
• Denoted as $\Omega$.
• Ex: For a die roll(6-sided) experiment, $\Omega = {1; 2; 3; 4; 5; 6}$.

Evénement

• A subset of the sample space, representing a collection of possible outcomes.
• Ex: In a six sided die roll, the event "obtaining an even number" is {2,4,6}

Probabilité

• A number between 0 and 1 that measures the likelihood of an event occurring.
• Denoted as $P(A)$ where A is the event.
• Ex: In a fair 6-sided die, $P(1) = \frac{1}{6}$

Calculs de probabilités

Probabilité d'un événement

• For equally likely outcomes, the probability of event A is: $P(A) = \frac{\text{Number of favorable outcomes for A}}{\text{Total number of possible outcomes}}$

Evénements particuliers

• Evénement impossible: probability is 0.
• Evénement certain: probability is 1.
• Evénement contraire: $\overline{A}$, $P(\overline{A}) = 1 - P(A)$.

Union et intersection d'événements

• Union ($A \cup B$): all outcomes in A or B.
• Intersection ($A \cap B$): all outcomes in both A and B.
• Formula: $P(A \cup B) = P(A) + P(B) - P(A \cap B)$

Evénements incompatibles

• Events that cannot occur at the same time.
• $P(A \cup B) = P(A) + P(B)$

Periodic Motion

• Motion that repeats itself at equal intervals of time.

Period (T)

• Time required for one complete cycle or oscillation.
• Cycle is one complete round trip.
• Unit: seconds (s)

Frequency (f)

• The number of cycles or oscillations per unit of time.
• $f = \frac{1}{T}$
• Unit: Hertz (Hz) or $s^{-1}$

Simple Harmonic Motion (SHM)

• Special type of periodic motion where the restoring force is directly proportional to the displacement, and acts in the opposite direction.
• $F = -kx$
• restoring force is directly proportional to the displacement.

Amplitude (A)

• Maximum displacement from equilibrium.

SHM and Circular Motion

• SHM is the projection of uniform circular motion onto a diameter.

Velocity in SHM

• The velocity related formula is: $v = \frac{dx}{dt} = -A\omega\sin(\omega t)$
• The maximum related formula is: $v_{max} = A\omega$

Acceleration in SHM

• The acceleration related formula is: $a = \frac{dv}{dt} = -A\omega^2\cos(\omega t) = -\omega^2 x$
• The maximum related formula is: $a_{max} = A\omega^2$

Angular Frequency

• $\omega = 2\pi f = \frac{2\pi}{T}$

SHM Example: Spring-Mass System

• For a spring-mass system, the angular frequency is: $\omega = \sqrt{\frac{k}{m}}$
• And the period is: $T = 2\pi\sqrt{\frac{m}{k}}$
• Note: The period and frequency of SHM are independent of the amplitude.*

Introduction

• The autonomic nervous system (ANS) is a control system that acts unconsciously.
• Regulates many bodily functions such as heart rate, digestion, sexual arousal, etc.

Divisions

• The sympathetic nervous system (SNS) is the "fight or flight".
• The parasympathetic nervous system (PNS) is the "rest and digest".
• Enteric nervous system (ENS) is the third division.
• The ENS is a network of neurons in the walls of the gastrointestinal tract and can function independently.

Neurotransmitters

• The main neurotransmitters are: Acetylcholine (ACh) and Norepinephrine (NE).
• ACh is used by all preganglionic neurons and postganglionic neurons in the PNS.
• NE is used by most postganglionic neurons in the SNS.

Receptors

• The receptors for ACh are called cholinergic receptors (nicotinic and muscarinic receptors).
• The receptors for NE are called adrenergic receptors ($\alpha$ and $\beta$ receptors).

Cholinergic Pharmacology

• Cholinergic agonists bind to and activate cholinergic receptors.
• They are also known as parasympathomimetics
• Cholinergic antagonists bind to and do not activate cholinergic receptors
• They are also known as parasympatholytics

Muscarinic antagonists

• Atropine
• Scopolamine
• Ipratropium

Nicotinic antagonists

• Tubocurarine
• Succinylcholine

Adrenergic Pharmacology

• Adrenergic agonists bind to and activate adrenergic receptors.
• Known as sympathomimetics.
• Adrenergic antagonists bind to adrenergic receptors but do not activate them.
• α antagonists block α receptors (Prazosin).
• β antagonists block β receptors (Propranolol).