BSEH Secondary Agriculture flashcards

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

Cropping intensity

Percentage ratio of total cropped area to net sown area in a year; above 100 means land grows more than one crop annually.

Land Equivalent Ratio

Sum of intercrop yields divided by sole-crop yields for each component; a value above 1 shows intercropping uses land more efficiently.

Water use efficiency

Marketable yield produced per unit of water applied, expressed as kg per cubic metre or kg per hectare per millimetre of irrigation.

Bulk density

Oven-dry mass of soil divided by its total volume including pore space, usually expressed in grams per cubic centimetre.

Cation exchange capacity

Total exchangeable cations a soil can hold per unit mass, measured in cmol(+)/kg; high values indicate strong nutrient retention.

Base saturation

Percentage of the cation exchange capacity occupied by exchangeable bases such as calcium, magnesium, potassium and sodium.

C3 versus C4 plants

C3 plants fix carbon via RuBisCO and photorespire; C4 plants use PEP carboxylase and have higher temperature and water use efficiency.

Apical dominance

Suppression of lateral bud growth by auxin produced in the shoot apex; removing the tip releases side shoots.

Floral formula notation

Symbols describing flower parts: K calyx, C corolla, A androecium, G gynoecium; parentheses show fusion and a line marks ovary position.

Economic threshold level

Pest population density at which control action should be taken to prevent the pest reaching the economic injury level.

Disease triangle

Concept that disease requires a susceptible host, a virulent pathogen and a favourable environment occurring together at the same time.

Koch's postulates

Four steps proving a pathogen causes a disease: isolate, culture, re-inoculate to reproduce symptoms, and re-isolate in pure culture.

Gestation period in cattle

Average duration of pregnancy in cattle, about 280 days; buffalo average about 310 days and sheep about 150 days.

Colostrum

First milk produced for three to five days after calving, rich in immunoglobulins and vitamin A, giving the calf passive immunity.

Gerber method

Standard test for milk fat content using sulphuric acid and amyl alcohol in a butyrometer, read as a percentage after centrifugation.

Grafting

Joining a scion to a rootstock so their cambium layers unite and grow as one plant, used for vigour or disease resistance.

Climacteric fruit

Fruit that shows a rise in respiration and ethylene production at ripening, such as banana, mango and tomato, allowing post-harvest ripening control.

Protected cultivation

Growing crops under polyhouse, greenhouse or shade net structures to control temperature, humidity, light and pest access.

Field efficiency

Actual field capacity divided by theoretical field capacity, expressed as a percentage, reflecting time lost to turns and adjustments.

Drawbar power

Power delivered at the tractor drawbar, calculated as draft force multiplied by forward speed with consistent units.

PTO shaft safety

Power take-off shafts must be fitted with guards and shields to prevent entanglement injuries during implement operation.

Reference evapotranspiration

Evapotranspiration from a standard reference crop under defined conditions; multiplied by the crop coefficient to estimate crop water use.

Permanent wilting point

Soil moisture content at about minus 15 bar tension where plants can no longer extract water and remain permanently wilted.

Drip irrigation

Method delivering water slowly to the root zone through emitters, saving water by reducing evaporation and deep percolation.

Gross margin

Gross return minus variable cost for an enterprise; used to compare enterprises when fixed costs are shared.

Internal rate of return

Discount rate at which a project's net present value equals zero; projects are acceptable when it exceeds the cost of capital.

Diffusion of innovations

Process by which an innovation spreads through a population, categorising adopters as innovators, early adopters, majorities and laggards.

Alley cropping

Agroforestry system with hedgerows of trees between crop strips; prunings supply mulch and reduce soil erosion.

Silvopasture

Agroforestry practice integrating trees with forage and livestock grazing on the same land unit for combined production.

Windbreak function

Rows of trees reduce wind speed and evaporation, protecting crops for a distance related to tree height and porosity.

Integrated nutrient management

Combining organic manure, biofertilizers and mineral fertilizers to match crop nutrient demand while reducing losses.

Bloom's taxonomy

Hierarchy of learning objectives from knowledge and comprehension through application, analysis, synthesis and evaluation, used to frame lesson objectives.