SACE Stage 2 Agricultural Systems key terms

The whole set of inputs, processes, outputs and feedbacks involved in producing a farm product, including land, labour, capital, water and management decisions acting together.

A single production activity on a farm, such as a wheat crop, a ewe flock or a dairy herd, whose costs and returns can be budgeted separately.

Any resource applied to a production system, such as seed, fertiliser, water, fuel, labour or capital, that is used up or transformed to create output.

The product, service or by-product that leaves a production system, measured as yield, liveweight gain, litres of milk or dollars of revenue.

A pathway where the result of a process changes the process itself, for example low soil organic matter reducing future yields, or high prices prompting more plantings.

The maximum stocking rate or production level a paddock or property can support over time without degrading its soil, pasture and water resources.

The number of animals, usually expressed as dry sheep equivalents, grazed on a defined area of land over a stated period.

A standard unit comparing feed demand, where one DSE is the feed required by a 50 kg dry sheep to maintain weight, allowing different classes of stock to be added.

The force of grazing relative to available pasture, combining animal numbers, animal weight and the amount of feed on offer at that time.

The proportion of pasture grown that is actually eaten by livestock rather than trampled, decomposed or left to senesce, often expressed as a percentage.

A forward calculation matching feed supply from pasture, hay and grain against livestock demand over a period, used to plan grazing and buying decisions.

A planned sequence of different crops or pastures on the same land over successive seasons, used to break disease cycles, manage weeds and improve soil.

A non-cereal crop grown mainly to interrupt the life cycle of cereal diseases and weeds, and to improve soil nitrogen or structure for following crops.

A plant family whose roots form nodules with rhizobia bacteria that convert atmospheric nitrogen into plant-available forms, enriching soil for later crops.

The biological conversion of atmospheric nitrogen gas into ammonia by rhizobia inside legume root nodules, making nitrogen available to plants.

The carbon-rich material in soil formed from decomposed plants, animals and microbes, which holds nutrients and water and improves structure and biological activity.

The arrangement of soil particles into aggregates and pores, which controls water infiltration, drainage, aeration and ease of root growth.

A measure of soil acidity or alkalinity on a scale of 0 to 14, controlling the availability of nutrients and the suitability of soil for particular plants.

The movement of nutrients such as nitrogen, phosphorus and potassium between soil, plants, animals and the atmosphere within a farming system.

The downward movement of soluble nutrients or salts through the soil profile with water, often removing nitrogen beyond the reach of plant roots.

The detachment and transport of soil by wind or water, accelerated when ground cover is lost, leaving thin topsoil and reducing long-term productivity.

The proportion of the soil surface protected by living plants, stubble or litter, which shields soil from raindrop impact and wind and conserves moisture.

The accumulation of soluble salts in soil or water to levels that reduce plant growth, often linked to rising water tables after clearing of deep-rooted vegetation.

Saturation of soil pores with water so that oxygen is excluded from roots, reducing growth and causing losses of nitrogen through denitrification.

Meeting current production needs while maintaining or improving the soil, water, biodiversity and economic resources on which future production depends.

The removal and long-term storage of atmospheric carbon dioxide in soil organic matter, vegetation or woody biomass, reducing greenhouse gas concentrations.

The variety of living organisms in an area, including plants, animals and soil microbes, which supports pest control, pollination and ecosystem stability.

A strategy combining monitoring, biological control, resistant varieties, cultural practices and targeted chemicals, using pesticides only when pest numbers justify them.

The pest or weed population at which the cost of control equals the value of the yield loss it would prevent, marking the point where action becomes worthwhile.

The regular, systematic collection of observations such as pasture mass, pest counts, soil tests or animal weights to guide management decisions.

The revenue from an enterprise minus its variable costs, expressed per hectare or per head, before fixed or overhead costs are deducted.

A cost that changes in proportion to the level of production, such as seed, fertiliser, drench or fuel, and is deducted when calculating a gross margin.

An overhead cost that must be paid regardless of production level, such as rates, insurance, machinery depreciation or permanent labour.

A financial plan combining all enterprise gross margins with fixed costs to estimate the total profit or loss of a property for a season.

The use of positioning, sensing and variable-rate technology to apply inputs at the right place and rate within a paddock, improving efficiency and reducing waste.

Applying fertiliser, seed or spray at differing rates across a paddock according to mapped variation in soil, yield or weeds.

Collecting information about land or crops from sensors on satellites, aircraft or drones, used to map vegetation cover, moisture and variability.

A sensor system on a harvester that records grain or crop yield continuously with its location, producing maps of within-paddock variation.

Collecting soil samples for laboratory analysis of pH, nutrients and organic carbon, providing the evidence base for fertiliser and liming decisions.