Soil Systems Flashcards
What is soil made up of?
Minerals Organic material Water Air spaces Biota
What is the function of rock particles in soil?
Provides the skeleton of the soil
What is humus?
Plant and animal matter in the process of decomposition
What is the function of decomposed material in soil?
Food for bacteria
Storage of nutrients
Soil moisture tension
Neutralises pH
What is the function of water in soil?
Transporting nutrients
Biota need water for life
Erosion prevention
What is the function of minerals in soil?
The texture of the soil, the permeability and ability to retain nutrients
Chemically weathers, releasing nutrients
The clay humic process
What is the function of air in the soil?
Plant and biota respiration
Drainage, “empty space”
Nitrogen fixation
What do living things do in the soil?
Break down large parts of organic matter
Large burrowing animals help to aerate the soil
They increase the surface area so more material can be decomposed
What is salinization?
When evaporation is greater than precipitation water from lower layers of the soil moves upwards along with minerals dissolved in the water. The water evaporates, leaving the minerals on the surface.
What is leaching?
When precipitation is greater than evaporation the water moves down into the soil, dissolving minerals and transporting them downwards.
What are the different horizons of soil?
O A E B C R
What are the three main minerals in soil?
Sand, silt and clay
What is the is the order of size of sand silt and clay?
Clay smallest
Silt
Sand largest
What is a soil called if it has a fairly equal proportion of clay silt and sand?
A loam
Properties of sand particles:
They are round so they have more air spaces in between. This means water drains quickly and easily Nutrients also leach easily.
Properties of clay particles:
Oblong in shape, less air spaces so get water logged easily. Electrostatic charges between particles.
What do the electrostatic charges on clay particles attract?
Humic acids
What are macronutrients?
Nutrients needed in larger supply
What are micronutrients?
Nutrients needed in a smaller supply, still very necessary
Macronutrient examples:
N P K
What is porosity?
The amount of space between particles
What is permeability?
How easily gases and liquids can pass through the soil
Name the processes in the nitrogen cycle:
Nitrogen fixation Nitrification Denitrification Assimilation Decomposition
What is nitrogen fixation?
Atmospheric nitrification is transformed into a soluble form, ammonium.
What is nitrification?
A process whereby soluble nitrogen is transformed into a form that is useful to plants. This process happens by bacteria in the soil.
What is denitrification?
A process whereby nitrate is transformed into atmospheric nitrogen.
What is assimilation in the nitrogen cycle?
A process whereby nitrogen becomes part of the plant tissue.
What is decomposition in the nitrogen cycle?
When organic matter is decomposed the nitrogen in it reenters the soil where it is then broken down by bacteria.
