BSEH Secondary Agriculture key terms

The relative proportion of sand, silt and clay particles in a soil, determined by particle size. It controls water holding, drainage, aeration and workability, and is not easily changed by management.

The arrangement of soil particles into aggregates or peds, giving porosity and stability. Good structure improves aeration, root penetration and infiltration; it can be damaged by compaction and depleted organic matter.

The total negative charge on soil particles able to hold exchangeable cations such as calcium, magnesium and potassium. High CEC soils retain nutrients better and resist pH change more strongly.

The percentage of the cation exchange capacity occupied by basic cations (calcium, magnesium, potassium, sodium) rather than hydrogen and aluminium. It indicates soil fertility status and acidity level.

A measure of soil acidity or alkalinity on a logarithmic scale from 0 to 14. It governs nutrient availability, microbial activity and choice of crops, lime or gypsum amendments.

The water content remaining in a soil after excess gravitational water has drained away, usually one to three days after saturation. It represents the upper limit of plant-available water storage.

The soil water content at which plants can no longer extract water and remain wilted even in a humid atmosphere. Water below this point is tightly held and unavailable to roots.

The amount of water a soil can store that is usable by plants, calculated as the difference between field capacity and permanent wilting point. It guides irrigation scheduling and drought planning.

The mass of dry soil per unit volume, including pore space, usually expressed in grams per cubic centimetre. High values indicate compaction that restricts roots and water movement.

The compression of soil that reduces pore space and increases bulk density, often caused by machinery traffic, tillage or grazing on wet soils. It limits root growth, infiltration and aeration.

The application of calcium or magnesium carbonate materials to raise soil pH and reduce exchangeable aluminium. It improves nutrient availability and microbial activity, but rates must follow soil test results.

The process by which green plants use light energy to convert carbon dioxide and water into carbohydrates, releasing oxygen. It is the primary source of dry matter in crops and forage.

The loss of water vapour from plant surfaces, mainly through stomata, which drives water and nutrient uptake. It cools leaves and is a major component of crop water use.

Small pores in the leaf epidermis bounded by guard cells that regulate gas exchange and water loss. Their opening and closing balances carbon dioxide uptake against transpiration.

The balance between plant organs that produce assimilates, such as mature leaves, and organs that consume or store them, such as grain, tubers or fruits. It determines yield potential and harvest index.

The ratio of marketable or grain yield to total above-ground biological yield of a crop. A high value shows efficient partitioning of dry matter into the harvested product.

The amount of crop dry matter or economic yield produced per unit of water used, often expressed as kilograms per hectare per millimetre. It is improved by irrigation scheduling, mulching and suitable varieties.

A decision framework combining resistant varieties, cultural, biological, mechanical and chemical tactics, with pesticides used only when monitoring shows they are economically justified. It aims at sustainable, low-risk control.

The pest population density at which control measures should be applied to prevent the pest from reaching the level causing economic loss. It guides scouting and spray decisions.

The suppression of pests using living organisms such as predators, parasitoids and pathogens. It is a core IPM component that reduces reliance on chemical pesticides.

Systematic regular monitoring of pest populations and crop damage through field scouting and trapping. It provides the evidence needed to apply economic thresholds and time interventions.

A feed mixture supplying all nutrients in the proportions and amounts needed by an animal for maintenance and a stated production level. It prevents deficiency and excess while keeping feed cost efficient.

A measure of the energy value of a feed, summing digestible carbohydrates, protein and fat (fat adjusted for its higher energy content). It is used to balance rations for livestock.

The units of feed consumed per unit of animal product produced, such as kilograms of feed per kilogram of milk or live weight gain. Lower values indicate more efficient feeding.

The first milk secreted after parturition, rich in antibodies, protein and vitamins. Newborn calves and other young stock must receive it within the first hours of life for passive immunity.

The administration of anthelmintic drugs to remove internal parasites from livestock. Timing and drug choice should follow faecal examination, body condition and grazing management to limit resistance.

The proportion of seeds in a lot that are alive and capable of germinating under suitable conditions. It is tested by germination tests and affects seeding rate calculations.

The proportion of seeds in a sample that produce normal seedlings under standard test conditions within a specified period. It is used with purity to compute the real seeding rate.

The quantity of seed sown per unit area, adjusted for germination percentage, purity, seed size and desired plant population. Correct rates help avoid overcrowding or thin stands.

The number of plants per unit area at a given growth stage. It interacts with row spacing and plant arrangement to determine light capture, competition and final yield.

The pattern of crops and their sequence and management on a farm over time, including monocropping, multiple cropping and rotations. It influences soil fertility, pests and farm income.

The planned sequence of different crops on the same land over successive seasons. It interrupts pest and disease cycles, balances nutrients and helps maintain soil organic matter.

A crop grown specifically to be incorporated into the soil while still green to add organic matter and nutrients, especially nitrogen from legumes. It improves structure and biological activity.

The living and dead plant and animal residues in soil at various stages of decomposition, including humus. It improves structure, water holding, nutrient supply and microbial activity.

Covering the soil surface with crop residues, plastic film or other material to reduce evaporation, suppress weeds and moderate soil temperature. It conserves moisture and protects the surface from erosion.

A method delivering water slowly and directly to the root zone through emitters along tubes. It saves water, limits weed growth and allows fertigation, but requires filtration and maintenance.

The application of soluble fertilisers through an irrigation system, usually drip, so nutrients reach the root zone with water. It improves nutrient use efficiency but needs careful concentration control.

The growth stage at which water shortage causes the greatest yield loss, such as flowering or grain filling. Irrigating at these stages gives the best return per unit of water.

Mechanical manipulation of soil to prepare a seedbed, control weeds and manage residues. Its intensity affects structure, organic matter loss, erosion risk and fuel use.

A farming system based on minimum soil disturbance, permanent soil cover and crop diversification. It reduces erosion and fuel use while improving soil health and moisture retention.

The ratio of total benefits to total costs of an enterprise or practice, used to judge economic viability. A ratio above one indicates returns exceed costs.

Gross income from an enterprise minus its variable costs, excluding fixed costs. It is used to compare enterprises and plan resource allocation on the farm.

A written financial plan estimating income, costs and returns for a farm or enterprise over a period. Partial, whole-farm and cash-flow budgets support decisions and credit applications.

A planned technique used by extension workers to help farmers learn, ranging from individual farm visits to group meetings, demonstrations and mass media. Choice depends on audience size and purpose.

A field site where a proven practice is compared with local practice under farmer conditions. It builds confidence through visible results and is a widely used group extension method.

The mental stages a farmer passes through before fully using an innovation: awareness, interest, evaluation, trial and adoption. Extension efforts should match the stage of each farmer.

Deliberate integration of trees or shrubs with crops or livestock on the same land unit. It diversifies income, improves soil and microclimate, and provides fuel and fodder.

An agroforestry practice of growing crops between hedgerows of trees or shrubs, whose prunings supply mulch or green manure. It controls erosion and adds organic matter and nitrogen.

A structured outline of objectives, content, teaching activities, resources and assessment for a single lesson. It sequences learning and keeps instruction aligned with stated competencies.

A curriculum organised around what learners can actually do in real situations rather than only content coverage. It states measurable learning outcomes and emphasises applied skills.

Ongoing assessment during teaching that provides feedback to improve learning, such as observation, questioning and practical checklists. It is distinct from final grading.