Soil System

Inputs (5)

• organisms/organic matter

• water

• air/gas

• minerals

• energy

organisms/organic matter (Inputs)

Organisms (biosphere) live in the soil and they provide inputs in various forms. Organic matter, derived from living or once-living organisms in the biosphere

• leaf litter

•  dead animal biomass 

• Manure

Water (inputs)

It enters the soil system as precipitation, humidity and through surface water such as rivers and streams. Water influences soil texture, soil structure, and the ability of soil to support life by affecting nutrient availability and biological activity

Air/gas (inputs)

Oxygen, carbon dioxide, and nitrogen, diffuse into the pores between soil particles. This diffusion of gases impacts the chemical composition of soil and provides essential elements for biological processes such as plant growth and decomposition.

Minerals (inputs)

They come from the weathering of parent material such as rocks, or from wind-blown or water-borne deposition or decomposition. These minerals include phosphorus, nitrogen and potassium

Energy (inputs) (2)

The soil receives solar energy from the Sun, and also receives thermal energy (heat) from the cellular respiration of the organisms in the soil.

Storages (4)

• water

• soil

• organisms

• minerals

water (storage)

 Water is a vital storage in soil, held within the pores between soil particles, but also deeper in soil as groundwater.. Water is important for plant growth, is a solvent for nutrients, and is essential for the biological activities of all soil organisms.

soil (storage)

Soil stores gases such as oxygen, carbon dioxide and nitrogen. These gases fill the gaps between soil particles and are vital for biological processes. Different soil textures contain different proportions of air spaces.

organisms (storage) 

Plants and animals store nutrients in their bodies. When they die, their organic matter is broken down by decomposers, releasing nutrients into the soil. The decomposition process also converts organic material into inorganic matter, which further contributes to the nutrients present in the soil.

Minerals (storage)

Minerals such as phosphorus, nitrogen and potassium, are stored in soils, and form part of the soil composition.

Flows (5)

• water

• air/gas

• organisms/organic matter

• minerals

• energy

water (flow) (5)

• Infiltration

• Percolation

• Groundwater flow

• Erosion

• Evaporation:

Infiltration 

This is a transfer process where water from precipitation or irrigation seeps from the surface into the soil

Percolation

After infiltration, water moves downward through the soil, a transfer that can lead to groundwater flow.

Groundwater flow

Water moves horizontally in soils, transferring nutrients and minerals through different soil layers.

Erosion 

A process whereby soil or rock is worn away and transported by wind or water. Here, Water transfers soil particles, often leading to loss of topsoil

Evaporation

Water is transformed from a liquid to a vapour, and released by soil into the atmosphere.

Air/gas (flow) (2)

• aeration

• erosion

aeration (flow) 

This transfer involves the movement of air in, out, and through soil. Natural soil aeration is caused by soil organisms, the movement of water, and the decomposition of organic matter, all of which create and maintain air pockets (macropores) in the soil. These natural processes allow gases, especially oxygen, to move between the atmosphere and the soil

erosion (flow)

Wind can transfer soil particles and gases, often leading to loss of topsoil

Organisms/organic matter (flows) (3)

• biological mixing

• decomposition

• soil aggregation

biological mixing 

A transfer caused by organisms such as earthworms mixing the soil, that helps to aerate and move nutrients through soils.

Decomposition

A transformation where organic matter is broken down by decomposers, releasing nutrients and energy for plant life

soil aggregation 

Decaying organic matter releases humus that acts as a cementing agent to bind soil particles into stable clumps. This improves soil structure by creating larger pores, which increases water infiltration and retention, aeration

minerals (flows) (3)

• weathering

• leaching

• salinization

weathering

continuously breaking down parent rock into smaller mineral particles and transforming these into soil (transformation)  This forms soil and releases minerals.

parent rock

the original rock or geological material from which a different rock or soil forms through processes like weathering, metamorphism, or erosion

Leaching 

The process of water carrying away nutrients or minerals from the soil, often due to excessive rainfall or irrigation.

Salinization

A transformation that results in salts accumulating in soil, often due to poor drainage and evaporation, affecting soil fertility.

Energy (flow) (1)

nutrient cycling

Nutrient cycling 

involves both transfers and transformations in the carbon and nitrogen cycles, where energy stored in organic matter is released through decomposition and then used by plants and other organisms

Outputs (4)

• water and minerals

• air and gas

• organisms / organic matter

• energy

Water and minerals (output)

Plants absorb water and minerals from the soil through their roots in a process called plant uptake. This is vital for their growth, transferring these elements to the biosphere.

Air and gas (output) 

Soil releases gases, including carbon dioxide and oxygen, which diffuse into the atmosphere, playing a role in processes such as photosynthesis and climate regulation.

organisms / organic matter (output)

Wind and water can erode soil, transporting soil particles and organic matter. Eroded soil can reshape the lithosphere and affect the composition of the hydrosphere.

Energy (output)

The energy stored in organic matter in soils is transferred to the biosphere when consumed by organisms. In addition, thermal energy (heat) is released by soils into the atmosphere over time. This is called infrared radiation.