LGCSE Agriculture (0179) key terms

A vertical section through soil from the surface down to the parent material, showing distinct layers called horizons. Farmers examine it to judge rooting depth, drainage and fertility before choosing crops or land uses.

A layer within a soil profile that differs from the layers above and below in colour, texture, structure or organic matter content. Horizons are labelled O, A, E, B, C and R from top to bottom.

The uppermost cultivated layer of soil, usually dark and rich in organic matter, roots and soil organisms. It is the layer most affected by ploughing, fertiliser application and erosion, and it supplies most crop nutrients.

The layer beneath the topsoil, usually paler and lower in organic matter but important for water storage and root anchorage. Compacted or poorly drained subsoil restricts rooting and reduces yields even when topsoil is fertile.

The relative proportions of sand, silt and clay particles in a soil. Texture controls water-holding capacity, drainage, aeration and workability, so it guides decisions on irrigation, tillage timing and crop choice.

The way soil particles group together into crumbs, blocks or clods, creating pore spaces. Good structure allows air, water and roots to move freely; poor structure leads to crusting, waterlogging or hard pans.

A balanced soil containing moderate amounts of sand, silt and clay, often described as the ideal agricultural soil. It holds moisture without waterlogging, drains reasonably and is easy to cultivate across many crops.

The dark, stable, fully decomposed part of soil organic matter. Humus improves structure, holds water and nutrients, buffers pH and feeds soil organisms, making it a key indicator of soil fertility.

A measure of soil acidity or alkalinity on a scale from 0 to 14, where 7 is neutral. Most crops grow best between pH 5.5 and 7.0; pH affects nutrient availability, so lime or gypsum may be applied.

The removal of topsoil by wind, water or tillage faster than it can form. It reduces fertility, pollutes waterways and lowers yields; control relies on cover, contour farming, terraces and windbreaks.

Compression of soil particles that squeezes out pore space, forming hard layers that resist roots and water. It is caused by machinery traffic, treading by livestock and working wet soil, and is relieved by loosening or deep tillage.

Growing different crops in a planned sequence on the same land over successive seasons. Rotation breaks pest and disease cycles, balances nutrient use, improves soil structure and reduces reliance on chemical inputs.

Growing a single crop species on the same land year after year. It simplifies management but builds up soil-borne pests and diseases, depletes specific nutrients and increases dependence on fertilisers and pesticides.

Growing two or more crops together in the same field at the same time, often in rows or strips. It spreads risk, uses light and nutrients more fully and can suppress pests, but complicates harvesting and mechanisation.

A crop grown mainly to protect and improve soil rather than for harvest, such as legumes or grasses. It reduces erosion, adds organic matter, suppresses weeds and can fix nitrogen before being incorporated or grazed.

A crop, usually a legume, grown and then ploughed into the soil while still green to add organic matter and nutrients. It improves structure, feeds soil life and can supply nitrogen for the following crop.

The conversion of atmospheric nitrogen gas into forms plants can use. Legumes do this through symbiotic bacteria in root nodules, while some free-living soil bacteria and industrial processes also fix nitrogen.

A plant of the pea and bean family that forms root nodules with nitrogen-fixing bacteria. Legumes supply protein-rich feed and grain and enrich soil nitrogen, making them valuable in rotations and intercropping.

Moving young seedlings from a nursery bed into the main field once they are strong enough. It allows careful spacing, uniform stands and earlier planting, but seedlings suffer transplant shock if roots are disturbed.

The prepared layer of soil in which seed is sown. A good seedbed is level, fine and firm with adequate moisture, so that seeds make good contact with soil and germinate evenly.

The distance left between plants within a row and between rows. Correct spacing gives each plant enough light, water and nutrients, eases weeding and harvesting, and prevents overcrowding and disease spread.

Removing surplus seedlings from a row so the remaining plants are spaced correctly. It reduces competition for light, water and nutrients and helps produce stronger, more uniform plants and better yields.

A hoofed mammal with a four-chambered stomach that ferments plant fibre with microbes. Cattle, sheep and goats are ruminants, able to digest roughage that non-ruminants such as pigs and poultry cannot use efficiently.

Bulky feed high in fibre and low in energy, such as grass, hay, silage and straw. It is essential for ruminant digestion and rumen health, though it must be supplemented for high production levels.

Feed low in fibre and rich in energy or protein, such as cereal grains, oilseed meals and formulated rations. It supplements roughage for growth, pregnancy and milk production but must be introduced gradually.

A high-moisture forage preserved by controlled fermentation in a silo or clamp. Lactic acid lowers the pH and prevents spoilage, allowing grass or maize to be stored as winter feed for livestock.

The amount of feed consumed divided by the liveweight gain or product output produced. A lower ratio means more efficient feed use; it is a key measure of profitability in livestock enterprises.

The length of pregnancy from conception to birth for a particular species. Knowing it allows farmers to plan mating dates, feeding and housing so that births occur at a favourable time.

The recurring period of sexual receptivity in female mammals, during which mating can lead to conception. Detecting oestrus accurately is essential for timely service or artificial insemination and efficient breeding.

Placing semen collected from a selected male into a female's reproductive tract without natural mating. It allows wide use of superior sires, reduces disease transmission and lowers the cost of keeping males.

Choosing animals with desirable traits, such as growth rate or milk yield, to parent the next generation. It improves herd performance over time but requires records and may narrow genetic diversity.

Mechanical working of the soil by digging, ploughing, harrowing or cultivating. It prepares a seedbed, controls weeds and incorporates residues, but excessive tillage damages structure and increases erosion.

A primary tillage implement that cuts and turns the soil to a depth of roughly 15 to 30 centimetres. It buries weeds and residues and loosens compacted layers, but repeated use can damage soil structure.

A secondary tillage implement with discs, tines or spikes that breaks clods, levels the surface and controls small weeds. It follows the plough to produce a fine, firm seedbed before sowing.

A splined shaft on a tractor that transmits engine power to attached implements such as mowers, sprayers and balers. Its speed is standardised so implements from different makers can be driven safely.

The system of two lower arms and one upper link that attaches implements to the rear of a tractor and controls their working depth. It allows quick mounting and accurate depth control on uneven ground.

An expense that does not change with the level of production, such as land rent, insurance or machinery depreciation. Fixed costs must be covered regardless of output, so they influence enterprise choice.

An expense that changes directly with the amount produced, such as seed, fertiliser, feed and casual labour. Variable costs are subtracted from gross income to calculate the gross margin of an enterprise.

Gross output value minus variable costs for a single enterprise, before fixed costs are deducted. It allows farmers to compare enterprises and decide which combination best uses limited land, labour and capital.

The level of output or price at which total revenue equals total costs, so neither profit nor loss is made. Knowing it helps farmers set minimum production targets and judge price risks.

The route a product takes from farm to final buyer, such as direct sales, cooperatives, wholesalers or processors. Shorter channels often raise the farmer's share of the retail price but demand more handling.

The sequence of activities and businesses that add value to a farm product from production through processing, distribution and retail. Understanding it helps farmers find where profit is made and where to improve quality.

Growing one crop on the same land season after season, a form of continuous monoculture. It is simple to mechanise and market but raises pest, disease and soil fertility risks unless carefully managed.

The variety of living organisms in a habitat, including crops, livestock, insects, birds and soil life. Higher biodiversity supports pollination, pest control and resilience, and is reduced by intensive monoculture and habitat loss.

The benefits people obtain from functioning ecosystems, such as pollination, pest control, water purification, soil formation and climate regulation. Agriculture both depends on and can damage these services.

Managing a farm so it meets present needs without reducing the ability of future generations to meet theirs. It balances profitability, environmental protection and social welfare, and is assessed through soil, water and biodiversity indicators.

Deliberately growing trees or shrubs together with crops or livestock on the same land. It provides shade, fodder, fuelwood and wind protection, improves soil and diversifies income, though competition for water and light must be managed.

A strategy that combines cultural, biological, mechanical and chemical controls, using pesticides only when pest numbers exceed a threshold. It reduces costs and resistance while protecting beneficial organisms and the environment.

Using natural enemies such as predators, parasites or pathogens to keep pest populations below damaging levels. It is a component of integrated pest management and avoids many of the side effects of chemical sprays.

A planned experiment carried out in the field to compare treatments, such as varieties or fertiliser rates, under real conditions. Replication, randomisation and control plots are used so that results can be trusted.

A plot in an experiment that receives no treatment, or the standard treatment, so its results can be compared with treated plots. It shows what would have happened without the treatment being tested.

Repeating each treatment several times in an experiment so that natural variation can be measured and chance effects reduced. More replicates increase confidence that observed differences are real.

Allocating treatments to plots by chance rather than by choice, so that hidden differences in soil or position do not favour one treatment. It is a basic safeguard against bias in field experiments.

A square frame of known area placed on the ground to sample plants, weeds or soil organisms. Counting within several randomly placed quadrats gives an estimate of population density across a field.

A line or narrow strip laid across a field or habitat along which observations are recorded at intervals. It is used to study how vegetation or soil changes with distance, slope or management.