Soil Science Flashcards
Alluvial
Very variable profiles from gravel to silty clay and often contain rounded pebbles and silt
Organic layer
The top layer of the soil that is rich in organic matter
Organic layer
The top layer of the soil that is rich in organic matter
Bagshot podsol
Forms on well drained acid sites under conifers and an iron pan forms
Chalk
Shallow, fertile soil over chalk or limestone with a high pH
Topsoil
The region of intense biological activity that’s found below the o horizon and is dark in colour because it contains the maximum amount of OM
Brown earth
Brown indistinct horizons that form on well drained soil
Gley
Seen in waterlogged clay and poorly drained soils where the soil turns blue-grey
Micropores
Tiny pores (less than 0.2 microns)
Mineral
An element with a specific and essential role for the completion of a plants life-cycle
Soil ameliorant
A substance that improves the physical condition of the soil
Nitrification
A process carried out by nitrifying bacteria which transfers soil ammonium into nitrates which plants can incorporate into their own tissues
Gravitational water
This is the water that will drain from the soil due to gravity. Eg - water in macropores
Saturation point
When all the pore spaces are filled with water
Field capacity
This is the ideal amount of water in the soil for plants and occurs when the macropores are filled and the micropore and mesopores are water filled
Macropores
Large pores (more than 60 microns or 0.06 mm)
Secondary nutrients
Essential but needed in smaller quantities than primary nutrients. They are rarely limiting to growth sucess
Primary nutrients
Nutrients required in the largest amounts. Essential for plant cell functioning. Deficiency of these nutrients contributes to reduced plant growth, health and yield
Capillary action
The tendency of a liquid to rise in narrow tubes or to be drawn into small openings
Soil moisture defecit
This is the water required by rain/ irrigation to raise the soil back to field capacity
Unavailable water
This is the water in micropores that is unavailable to plant
Plant available water
The water held in the mesopores that plants can take up
Permanent wilting point
When all the water has been removed from the macro and mesopores due to drainage, plant uptake and evaporation from the soil surface
Nitrogen cycle
The biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheres, terrestrial and marine ecosystems
Eluviation
Removal of dissolved or suspended material from a layer or layers of the soil by the movement of water when rainfall exceeds evaporation. Such loss of material in solution is often referred to as leaching and this influences soil compaction
Fertiliser
Concentrated source of nutrients that makes plants grow bigger and faster
Nitrogen assimilation
How plants get nitrogen
Ammonification
The remains of all living things and their waste products are decomposed by microorganisms in the process of ammonification which yields ammonia and ammonium
Irrigation
Watering plants to raise the soil back to field capacity and to replace the soil moisture defecit
Antagonism
Overdose of certain elements can displace other nutrients
Aggregate
Lumps of soil formed by natural processes
Horizon
Horizontal layers visible in a profile
Soil profiles
Vertical face of a soil pit
Unstructured soil
Uniform pore sizes and poor permeability
Structured soil
Variable pore sizes and better permeability
Structure
The joining together of soil grains into aggregates and is the arrangement of soil in a profile
Porosity
Total number of pores
Soil organic matter
A mixture of plant and animal remains, excreta and living organisms etc, added to the soil by natural means
Loam
A mixture of sand, silt and clay
Texture
Used to describe the feel of a substance, based upon the smoothness or roughness of its surface
Soil texture
Soil texture is determined by the size and proportions or ratio of the small individual mineral particles
Humus
Well rotted organic matter
Permeability
How easily air and water can travel through the soil connections
Leaching
A process of extracting a substance from a solid material that is dissolved in a liquid
Calcicoles
Alkaline loving plants
Calcifuges
Acid loving plants
Igneous rocks
Formed from molten Lava and they are mostly formed as the Earth’s crust cooled. Eg: granite
Sedimentary rocks
Formed in layers by weathering of other rocks and organisms. Eg: shale
Metamorphic rocks
Formed either from igneous or sedimentary rocks which have changed due to excess heat and pressure. Eg: marble
Physical weathering
The rocks are broken down into smaller pieces but the chemical composition of the rock remains the same. Eg: heating and cooling
Biological weathering
Caused by biological agents. Eg: plants and animals
Chemical weathering
Chemical means which cause permanent chemical changes. Eg: solution and oxidation
Soil
Soil is the growing medium for plants and their roots as it gives them water, mineral nutrients, oxygen and support
