NZ Scholarship Agricultural and Horticultural Science key terms

A managed farming system treated as an ecosystem, where soil, plants, animals, pests, water and people interact. Analysis focuses on energy flow, nutrient cycling and how management choices change these processes.

The movement of elements such as nitrogen, phosphorus and potassium between soil, plants, animals and water. Leaching, run-off, fixation and recycling by microbes all affect how much stays available to crops.

The downward movement of dissolved nutrients through soil beyond the root zone, so plants cannot use them. It is driven by rainfall or irrigation, and is worse on sandy, free-draining soils with little plant cover.

Conversion of atmospheric nitrogen gas into forms plants can use. Legumes do this through symbiotic rhizobia bacteria in root nodules; free-living soil bacteria and industrial fertiliser production also fix nitrogen.

Nutrient enrichment of waterways, usually by nitrogen and phosphorus run-off, causing algal blooms. Decay of the algae uses up oxygen, harming fish and other aquatic life, and often limiting farm discharges.

How soil particles bind into aggregates, creating pore spaces for air and water. Good structure supports root growth and drainage; compaction and cultivation damage can destroy it.

The proportions of sand, silt and clay particles in a soil. Texture strongly influences water-holding capacity, drainage, nutrient retention and how easily the soil is worked.

Compression of soil by machinery, stock or rainfall that squeezes out air spaces and increases bulk density. Roots struggle to penetrate, drainage slows, and surface ponding and run-off become more likely.

Structural damage to wet pasture by hooves pushing soil apart and creating deep muddy hollows. It reduces pasture growth and infiltration, and can persist for seasons if the soil is not rested.

The process where green plants use light energy to convert carbon dioxide and water into sugars and oxygen. It drives crop yield, dry matter production and the carbon inputs to soil.

The release of energy from sugars by living cells, using oxygen and producing carbon dioxide and water. In plants it consumes assimilate, so net growth is photosynthesis minus respiration losses.

Plant material with all water removed, expressed as a weight or percentage. It is the standard measure of pasture and crop yield and of feed value, allowing fair comparison between feeds.

The energy in feed that an animal can actually use after digestion losses, usually given in megajoules per kilogram of dry matter. It drives growth, milk production and maintenance.

The amount of product, such as milk, meat or eggs, produced per unit of feed consumed. Higher efficiency means less feed and land per unit of output, improving both profit and environmental footprint.

Controlling when, where and how hard animals graze to balance pasture recovery with feed supply. Rotation length, stocking rate and residual pasture levels all shape long-term pasture persistence.

The number of animals carried per unit of land, often expressed as stock units per hectare. It sets the balance between feed demand and pasture growth, affecting profit and environmental risk.

A standard measure of animal feed demand, based on a mature ewe grazing pasture. It allows different classes of livestock to be compared and total farm feed demand to be calculated.

The proportion of pasture grown that is actually eaten by animals rather than lost to decay, trampling or senescence. Raising utilisation lifts output per hectare without extra inputs.

A plant family whose members often form nitrogen-fixing nodules with rhizobia. In pastures, clovers and lucerne add nitrogen, improve feed quality and diversify the sward.

A nitrogen-fixing legume commonly sown in New Zealand pastures. It supplies nitrogen to companion grasses, improves feed quality, and is sensitive to shading, grazing pressure and pest damage.

A high-producing pasture grass widely used in temperate farming. It responds strongly to nitrogen and moisture, and its growth slows in cold or dry periods, creating seasonal feed gaps.

Growing different crops in a planned sequence on the same land. Rotations break pest and disease cycles, vary nutrient demand, and can improve soil structure and weed control.

A crop grown mainly to interrupt a pest, disease or weed cycle rather than for its own high return. It changes the soil and biology so the following crop performs better.

A decision framework combining monitoring, biological control, cultural practices and targeted chemicals. Chemical use is a last resort, chosen to minimise resistance, residues and harm to beneficial species.

The pest population level at which the cost of control equals the damage avoided. Spraying below it wastes money and selects for resistance; spraying above it prevents avoidable yield loss.

Using living organisms such as predators, parasitoids or pathogens to suppress pests. Success depends on establishing the agent, avoiding harm to it, and matching it to the pest's lifecycle.

The variety of species and genetic variation within a farm or landscape. Higher biodiversity can support pollination, pest control and resilience, and is influenced by habitat, chemicals and farming intensity.

A vegetated strip beside a stream or drain that filters run-off, stabilises banks and shades water. Fencing to exclude stock is a common measure to protect water quality.

Meeting current production needs without reducing the ability of future generations to farm. It combines economic viability, environmental limits and social expectations, and is judged across all three.

Gases such as methane, nitrous oxide and carbon dioxide released by farming that trap heat. Ruminant digestion, urine patches, fertiliser and fuel are the main on-farm sources.

A manufactured or mined product supplying plant-available nitrogen, such as urea or ammonium sulphate. Its use raises yield but carries risks of leaching, nitrous oxide emissions and cost.

The amount of water a soil can retain after free drainage, available to plants. It depends on texture, organic matter and structure, and determines irrigation need and drought resilience.

Applying water to crops or pasture to supplement rainfall. Scheduling, application efficiency and water source quality determine yield gains, costs and risks such as nutrient loss.

The harvestable output per unit area, such as tonnes per hectare or kilograms of milksolids. Yield is the product of plant growth, harvest index and losses, and is compared against a potential.

The improvement in a population's performance from selection and breeding over generations. It is measured as change per year and depends on selection accuracy, intensity and generation interval.

The weighted combination of traits a breeding programme aims to improve, reflecting market and farm goals. It defines what is selected for and must match the production system.

The proportion of variation in a trait that is due to genetic rather than environmental differences. High heritability means selection on individual performance is more reliable.

A prediction of an animal's genetic merit for a trait, accounting for its own records and those of relatives and herd-mates. It is used to rank candidates for selection.

The ability to sell produce into a particular market, governed by quality standards, traceability, food safety and biosecurity requirements. Failure to meet them can exclude a whole product line.

Measures that prevent pests and diseases entering and spreading on farms and across borders. On-farm practices include hygiene, movement control and surveillance.

Documented systems and checks that show a product consistently meets agreed standards. On farms this covers animal welfare, chemical residues, traceability and environmental practice.

The sequence of steps from input supply and production through processing, transport and retail to the consumer. Each step adds cost and value and influences product quality and price.