LGCSE Agriculture (0179) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Factors of production

The four inputs needed for farming: land, labour, capital and management. Management is the coordinating factor that decides how the other three are combined to produce output.

Weather versus climate

Weather is the short-term state of the atmosphere over hours or days. Climate is the average pattern over about 30 years, so it guides crop choice rather than daily field operations.

Mixed farming

A system where crops and livestock are produced on the same farm. Manure feeds the soil, crop residues and forage feed the animals, and income is spread across two enterprises.

Ecosystem services

Benefits people obtain from functioning ecosystems, such as pollination, water purification, nutrient cycling and erosion control. On farms these are unpaid outputs that support production.

Soil texture

The relative proportions of sand, silt and clay particles in a soil. Texture is felt by hand and classified on a textural triangle, and it controls drainage, water holding and workability.

Cation exchange capacity

The ability of a soil to hold positively charged nutrients such as calcium, magnesium and potassium on clay and organic matter surfaces. Higher CEC means greater nutrient retention.

Available water capacity

The water held in soil between field capacity and permanent wilting point. This is the portion plants can actually extract, and it is greater in loams and soils rich in organic matter.

Contour ploughing

Ploughing across a slope following the contour lines rather than up and down. It slows runoff, traps water and reduces soil loss on sloping cultivated land.

Soil pH and lime

pH measures soil acidity or alkalinity. Acid soils below about pH 5.5 are corrected by applying agricultural lime, which raises pH and improves nutrient availability for most crops.

Composite soil sample

A sample made by mixing 15 to 20 subsamples taken in a zigzag pattern across a field from the top 20 centimetres. It represents the field average for laboratory analysis.

Critical growth stage

The period when a crop is most sensitive to stress, usually flowering to grain filling. Water or nutrient shortage then causes the largest reduction in final yield.

Crop rotation

Growing different crops in sequence on the same land. It interrupts pest and disease cycles, restores nitrogen when legumes are included, and improves soil structure and weed control.

Plant population

The number of plants per unit area, calculated as 10 000 divided by row spacing times within-row spacing in metres. It determines competition, light capture and final yield.

Integrated pest management

A combined approach using resistant varieties, cultural methods, biological control and scouting against thresholds, with pesticides used only when justified and at the correct stage.

Seed viability

The proportion of seeds in a lot that will germinate and produce normal seedlings under favourable conditions, usually expressed as germination percentage in a standard test.

Post-harvest loss

Reduction in quantity or quality of produce between harvest and consumption. Causes include poor drying, insect and rodent damage, and storage moisture above safe levels.

Rumen fermentation

Microbial breakdown of fibrous feed in the rumen of cattle, sheep and goats. It lets ruminants use cellulose-rich forage that non-ruminants such as pigs and poultry cannot digest.

Roughage and concentrate

Roughages are bulky, high-fibre feeds such as grass, hay and silage. Concentrates are low-fibre, nutrient-dense feeds such as cereal grain and oilseed meal used to boost energy or protein.

Oestrous cycle

The recurring period of reproductive activity in female mammals, averaging about 21 days in cattle. Heat signs include standing to be mounted, restlessness and clear mucus discharge.

Deep litter system

A poultry housing method where birds live on a floor covered with dry absorbent bedding that is regularly stirred and replaced. Good ventilation and stocking density prevent disease.

Mouldboard plough

An implement with a curved blade that cuts, lifts and inverts the soil, burying weeds and crop residues. It is suited to clean seedbed preparation on workable soils.

Power take-off

A shaft at the rear of a tractor that transmits engine power to mounted or trailed implements such as rotary tillers, sprayers and balers. It must be disengaged before clearing blockages.

Drip irrigation

A system delivering water slowly through emitters directly to the root zone. It has high water use efficiency, reduces evaporation and leaf wetness, and suits scarce or costly water.

Pump head

The total height water must be lifted plus friction losses in pipes and fittings. Head and required flow rate together determine the pump power needed.

Gross margin

Gross output value minus variable costs for one enterprise. Fixed costs are excluded, so gross margins compare enterprises such as maize or poultry on a per-hectare or per-head basis.

Break-even yield

The output needed to cover total costs, calculated as total costs divided by price per unit. Producing above this yield gives a profit, below it a loss.

Straight-line depreciation

An accounting method spreading an asset cost evenly over its useful life. Annual depreciation equals purchase cost minus salvage value, divided by the number of useful years.

Marketing margin

The difference between the price paid by the final consumer and the price received by the farmer. A long chain of intermediaries usually widens the margin and shrinks the producer share.

Liebig's law of the minimum

Growth is limited by the resource in shortest supply, not by resources in abundance. Adding more of a non-limiting nutrient or factor does not increase yield.

Nitrogen fixation

Conversion of atmospheric nitrogen into plant-usable forms by bacteria, either free-living in soil or in root nodules of legumes such as beans, groundnuts and clover.

Conservation agriculture

A system based on three principles: minimum soil disturbance, permanent soil cover with residues or cover crops, and crop diversification through rotation. It reduces erosion and builds organic matter.

Field plot area

The size of a trial or field measured as length times width. Dividing square metres by 10 000 converts the area to hectares for yield and input calculations.