Pedosphere Flashcards
What is soil
Soil is the natural medium for the growth of plants
It is a natural body consisting of layers called soil horizons (weathered mineral materials, organic material, air, and water)
Soil is a thin layer, and the end product of combined influences or climate, topography, and organisms on rocks and minerals over time
What is Pedosphere
Pedology - study that deals with the nature of soils
Pedogenesis- formation of soil
How long does pedogenesis take
It can take between 200-1000 years to produce just 2.5cm of topsoil
This long time horizon makes soil a non-renewable resource
What does the soil contain that is essential to plant growth
Nitrogen, Potassium, Phosphorus, and other bio-elements such as calcium, magnesium, sulfur, chlorine, etc.
What is the use of soil
Soil is a medium for plant growth and we have depended on it for growth and sustenance
Other organisms also use it as shelter and survival (life depends a lot on this final sphere)
What is climate in soil formation
Climatic factors such as wind, rain, and temperature changes affect the speed of the weathering process
What are organisms in soil formation
Living organisms such as plants, animals, and bacteria add organic matter to oil
What is topography in soil formation
Land elevation affects exposure to sun, wind, and water and how soil moves
What is the parent material in soil formation
Attributes or qualities of parent material will influence the properties of the soil formed
How is time related to soil formation?
Soil formation can take decades, centuries, or even millennia
What are the 3 types of weathering
Mechanical, Physical, or Chemical
Physical is the disintegration of rocks into smaller fragments
Reactions under the influence bring about the other dissolved substances (usually acidic) in water
What is soil horizon?
What does time have to do with soil
The time it takes influences how thick and abundant organic materials are in the soil
Soil development
It occurs in stages with time and forms soil horizons or layers of distinct mineral context and texture
Soil horizons
It helps us see the changes in color, texture, and thickness
(In order of layers) O - A - E - B - C - R Horizons
What are the main layers of soil horizons
(A, B, C) correspond to the topsoil, subsoil, parent material; and an organic (O) horizon.
There are additional layers but these are not always present or in the same order.
Characteristics of O horizon
It is the organic layer and it is not always present
Characteristics of A and E horizon
It is the topsoil
The zone of organic materials is the most common layer
It is rich in humus (made up of organic materials)
It is rich since it has the highest microbial activity
What is the B and C Horizon
It is the subsoil (Elluviation and Illuviation)
The material in the subsoil is unaltered or not significantly altered
(C) It is characterized as the weathered parent material of the soil
What is elluviation
The result of rainfall pushing down clay and minerals lower in soil layers
Occurs in the A to E horizon
What is illuviation
The result of rainfall moving materials past the E horizon into the B horizon
What is the R horizon
It is the bottom of the bedrock
Parent material that is still consolidated
What are the different soil properties
Soil Texture
Soil Structure
Soil Color
Soil acidity
What is Soil texture
It is the study of different grain sizes
(Smallest to largest) Sand, silt, and Clay
A heterogeneous mixture is beneficial for plant growth
Coarser grains provide structural support
Finer grains absorb and retain nutrients
How is soil porosity related to soil texture
It is a quality that looks at the number of spaces or pores per area
How is soil permeability related to soil texture
It looks at the capability of water to pass through
How are soil permeability and porosity related to soil volume
They determine how much of the soil volume is occupied by water and air, which is important for plant health
Greater porosity and permeability mean a higher volume that can be occupied by water; lesser porosity and permeability mean a more tightly- packed and denser soil
What is soil structure?
It examines the tendency of soils to group together in lumps and aggregates called peds
Ped formation influences water movement, aeration, and porosity of the soil
The more it clumps, the more resistant to erosion
What is soil color
It reflects its composition. Dark-colored soils (black to very dark brown) indicate richer organic matter
It can reveal climatic conditions during soil formation
What is soil acidity
it reveals whether it is more alkaline or more acidic
The common range is 4-8
pH determines the solubility of some minerals needed for plant growth. Macronutrients are less at low pH and Micronutrients are less at high pH
What are the soil nutrients
Nitrogen (N) - is needed for plants to form new cells; essential for plant development
Phosphorus (P) - Needed for seed and root development and blooming
Potassium (K) - Needed for strong and sturdy stems
What is soil and plant dynamics
Organisms help spread and breakdown nutrients and break down humus
Mycorrhizae - soil minerals are absorbed by root-like structures of a fungus and are then transferred to the plant; the food produced from photosynthesis is taken up by the fungus
How is the soil cycle affecting the soil
It allows minerals and nutrients to cycle through soil to living organisms and back
What are soil problems
Agricultural impacts
Soil Erosion
Deforestation
Water logging and salinization
Desertification
What are the strategies for soil management
Integrated pest management - alternative use for pesticides (more natural)
Erosion control - Planting native crops is one way to stabilize soil
Conservation tillage - Tilling is reduced and instead, wastes are incorporated into the soil
Cropping strategies - Different ways of planting crops to utilize the soil
Vermicomposting - Natural process where worms improve soil quality by breaking down key nutrients
