Systems
In agriculture, understanding the flow of energy and matter within farming systems is needed to manage resources effectively and sustainably. Agricultural systems can be classified as open, closed, or isolated, depending on how they interact with their surroundings. .
Open Systems
Flow of Energy: Energy, such as sunlight, enters the system and energy can leave through processes like heat loss.
Flow of Matter: Matter, including water, nutrients, seeds, crops, and livestock, can enter and leave the farm system. Inputs like fertilisers, pesticides, and animal feed are added, while outputs include harvested crops, waste and emissions.
Example: A traditional farm is an open system because it depends on external inputs (e.g., fertilisers, water and seeds) and outputs (e.g., harvested produce and animal waste).
Closed Systems
Flow of Energy: Energy exchange occurs, such as the absorption of sunlight and the loss of heat, but this exchange is controlled.
Flow of Matter: Matter is largely recycled within the system, with minimal external inputs or outputs. Nutrients are reused, and waste is composted to enrich the soil.
Example: A permaculture farm aims to be a closed system, where organic waste is composted to fertilise plants, animals provide manure for the soil, and water is conserved and reused.
Isolated Systems
Flow of Energy: No exchange of energy with the environment; theoretically, the system is entirely insulated.
Flow of Matter: No matter enters or leaves the system, making it completely self-contained.
Example: True isolated systems do not exist in agriculture, as all farming systems exchange some level of energy or matter. However, highly controlled environments like some types of space agriculture or sealed biospheres attempt to mimic isolated systems by containing all resources within.
