UPMSP Class 12 Vocational Crop Science key terms

The branch of agriculture that deals with growing field crops and managing the soil, water and inputs they need, as distinct from raising animals or studying plants in the abstract.

Grouping crops as kharif (sown with monsoon rains), rabi (sown in winter) or zaid (short summer season) according to the weather in which they are normally grown in India.

A crop sown at the onset of the south-west monsoon and harvested in autumn, for example rice, maize, sorghum, pigeonpea and groundnut, which generally needs warm humid weather.

A crop sown after the monsoon in cooler weather and harvested in spring, such as wheat, barley, gram, lentil and mustard, often grown on residual soil moisture or with irrigation.

The ratio of total cropped area to net sown area in a year, usually expressed as a percentage; a value above 100 shows that land is being cropped more than once.

Growing a planned sequence of different crops on the same field over successive seasons to maintain fertility, interrupt pest cycles and spread risk and labour needs.

A vertical section through soil from the surface down to the parent material, showing distinct layers or horizons that differ in colour, texture and organic matter content.

The relative proportions of sand, silt and clay particles in a soil, which govern its water holding, drainage, aeration and workability and give the textural class name.

The way individual soil particles are bound together into aggregates, determining pore space, aeration, root penetration and resistance to erosion; good structure is granular and stable in water.

The total quantity of positively charged ions a soil can hold on the surfaces of clay and humus, measured in centimoles of charge per kilogram; higher values mean greater nutrient retention.

The proportion of the cation exchange capacity occupied by basic cations such as calcium, magnesium, potassium and sodium rather than by hydrogen and aluminium; it is expressed as a percentage.

A measure of the acidity or alkalinity of the soil solution on a scale from 0 to 14; it controls nutrient availability and the activity of many soil organisms.

An element that a plant must obtain to complete its life cycle, whose absence causes a specific deficiency symptom that only that element can correct; seventeen are recognised, grouped as macro and micro elements.

Supplying crop nutrients from a combination of mineral fertiliser, organic manure, crop residues and biological sources in balanced amounts, so that yields are sustained while soil health and costs are kept under control.

Well rotted mixture of animal dung, urine and bedding straw used as a bulky organic manure; it adds organic matter and several nutrients but has a low nutrient concentration.

Growing a quick leafy crop, often a legume such as sunhemp or dhaincha, and ploughing it into the soil while still green to add organic matter and nitrogen.

The resumption of growth by a viable seed, beginning with water uptake and ending with the emergence of the radicle, provided moisture, suitable temperature and oxygen are available.

The proportion of seeds in a lot that are alive and capable of germinating under favourable conditions, usually assessed by a germination test or a tetrazolium test.

A resting state in which a viable seed fails to germinate even when given adequate moisture, oxygen and temperature, because of a hard seed coat or internal chemical or physiological blocks.

The degree to which a seed lot of a named variety is free from off-types, natural crosses and other varieties, usually measured as the percentage of plants or seeds that are true to type.

Removing off-type, diseased or otherwise undesirable plants from a seed production field by hand or tool before they shed pollen or set seed, so that genetic purity is protected.

The minimum separation, in metres, required between a seed crop and any other crop or variety that could cross-pollinate it or contaminate the harvest, as fixed by seed certification standards.

An official system that verifies the varietal identity, genetic purity, physical purity, germination and health of seed through field inspection and laboratory testing, and issues a tag for certified seed.

Mechanical working of the soil to prepare a seedbed, control weeds and incorporate residues, carried out with implements such as the plough, harrow and cultivator.

Sowing a crop directly into undisturbed soil through the residue of the previous crop, with no ploughing, so that soil structure, moisture and organic matter are conserved and fuel use falls.

The prepared surface layer of soil in which seed is placed; a good seedbed is fine, firm, moist and free of clods and weeds so that germination and early seedling growth are even.

The water content a soil retains after excess water has drained away under gravity, usually a day or two after heavy rain or irrigation; water held above this level drains and is lost to the crop.

The soil water content at which a plant can no longer extract water and remains wilted even in a humid atmosphere; the water between this point and field capacity is available to crops.

Deciding when and how much to irrigate, using soil moisture status, crop stage and evaporation demand, so that water is applied before stress reduces yield but without waste.

Applying water slowly and directly to the root zone of each plant through emitters on tubes laid along the row, which saves water and keeps foliage dry compared with flooding the whole field.

Spreading a layer of crop residue, straw, plastic or other material over the soil surface to reduce evaporation, suppress weeds, moderate soil temperature and protect the surface from erosion.

A plant growing where it is not wanted, competing with the crop for water, nutrients, light and space and often harbouring pests or reducing produce quality and harvest efficiency.

The property by which a herbicide kills target weeds at a recommended dose while the crop survives, because of differences in uptake, translocation, metabolism or placement between crop and weed.

Combining resistant varieties, cultural practices, biological control, monitoring and judicious pesticide use so that pest populations are kept below damaging levels with least harm to people and the environment.

The pest population density at which control measures should be applied to prevent the pest from rising to a level that causes economic loss greater than the cost of control.

A plant of the pea family that forms nodules on its roots with nitrogen-fixing bacteria, so it can obtain nitrogen from the air and usually leaves nitrogen in the soil for the next crop.

The growth stage at which shortage of a nutrient causes the greatest and least recoverable loss in yield, so that fertiliser or irrigation must not be delayed past it.

The total expense incurred in raising a crop, including seed, fertiliser, pesticide, irrigation, hired and family labour, machinery and interest, used to work out profitability.

Gross return from a crop or enterprise minus its variable costs; it measures how much each enterprise contributes towards fixed costs and profit and is used to compare enterprises.

The ratio of the value of output to the cost of production for a crop or enterprise; a value above one indicates that returns exceed the costs incurred.