MSCE Agriculture key terms

The difference between the yield a crop could reach under best local management and the yield farmers actually obtain. It shows where improved seed, fertiliser, timing or pest control could raise production without new land.

The number of crops harvested from one field in a year, expressed as a ratio to a single crop. Higher intensity raises output per hectare but increases nutrient removal and pest pressure.

Growing different crops in a planned sequence on the same land across seasons. It interrupts pest and disease cycles, spreads nutrient demand and helps maintain soil structure and organic matter.

A decision framework that combines monitoring, resistant varieties, cultural methods, biological control and targeted pesticides, applying chemicals only when pest numbers justify it. The aim is economic control with least harm to people and the environment.

The pest population level at which the cost of control equals the value of crop loss avoided. Treating below this level wastes money and selects for resistance; waiting beyond it means avoidable yield loss.

Units of feed consumed per unit of animal product gained, such as kilograms of feed per kilogram of liveweight or milk. Lower values mean more efficient animals and cheaper production.

The mass of feed an animal eats after moisture is removed, usually expressed daily. It sets the ceiling on nutrient supply and therefore on milk yield or growth, so ration formulation starts from it.

The portion of feed energy available to the animal after losses in faeces, urine and fermentation gases. Rations are balanced on it because it directly limits growth, reproduction and milk production.

An estimate of how much an animal's genes are expected to shift the performance of its offspring compared with an average animal. It is used to rank candidates for selection within a breeding programme.

The gap between the average performance of animals chosen as parents and the average of the whole population. Combined with heritability, it predicts the genetic gain achieved per generation.

The share of observed variation in a trait that is due to genetic differences among animals in a population. High values mean selection responds quickly; low values mean management and environment dominate.

The superior performance of crossbred offspring relative to the average of their parent lines, often seen in growth, survival and fertility. It is greatest for lowly heritable traits and is not fully passed to the next generation.

The number of negatively charged sites on soil particles able to hold exchangeable cations such as calcium, magnesium and potassium, measured in centimoles of charge per kilogram. It indicates how well a soil stores nutrients against leaching.

The percentage of cation exchange sites occupied by basic cations rather than aluminium and hydrogen. High values indicate a fertile, near-neutral soil; low values point to acidity and possible aluminium toxicity.

The resistance of a soil's acidity to change when acid or lime is added. Soils with high clay and organic matter content resist pH change strongly, so liming them needs larger amounts than sandy soils.

The quantity of agricultural lime needed to raise soil pH to a target level for a chosen crop. It is estimated from soil texture, organic matter and the measured pH change needed, not from pH alone.

The share of applied irrigation water that must pass beyond the root zone to carry away accumulated salts. Applying less than this allows salinity to build up even when good-quality water is used.

The concentration of soluble salts in the soil solution, usually judged from electrical conductivity of a soil extract. Excess salts draw water away from roots and reduce germination, growth and yield.

A high proportion of sodium among exchangeable cations, which disperses clay, destroys structure and slows water infiltration. It is corrected with gypsum and organic matter rather than by leaching alone.

Gross output value of an enterprise minus its variable costs, leaving the return to fixed costs such as land, machinery and labour. Comparing gross margins per hectare helps rank competing crop or livestock options.

A cost that changes with the level of production, such as seed, fertiliser, fuel, casual labour and veterinary supplies. These costs are deducted from output when calculating gross margin.

The output per hectare at which revenue exactly covers the costs of growing that crop. It allows a farmer to judge risk when comparing a high-input, high-yield option with a low-input one.

The value of the best alternative given up when a resource such as land, labour or capital is used in one enterprise. It is the correct basis for deciding between competing uses of a scarce resource.

Systematically kept physical and financial data on production, inputs, sales and cash flow. Reliable records underpin gross margin analysis, loan applications, tax compliance and detection of unprofitable enterprises.

A splined shaft at the rear of a tractor that transmits engine power to implements such as mowers, sprayers and balers. Its standard speed and spline size must match the implement's drive shaft.

A tractor hitch with two lower arms and one top link that attaches and lifts implements. It controls implement depth and transfer of weight, improving traction and stability during field work.

The pulling force an implement needs to do its work at a given speed and soil condition. Matching it to a tractor's available drawbar power prevents overloading, wheel slip and excessive fuel use.

Deciding when and how much to irrigate, using soil moisture, crop water use or plant indicators. Good scheduling avoids yield loss from stress while cutting pumping costs and waterlogging.

The water content remaining in a soil after excess water has drained freely, typically a day or two after rain or irrigation. It marks the upper useful limit of stored soil water for crops.

The soil water content below which a plant can no longer extract water and stays wilted even in a humid atmosphere. The water held between field capacity and this point is what crops can actually use.

A structured survey of farmers' problems, practices and information sources used to plan extension activities. It prevents advisers from pushing messages farmers do not need or cannot apply.

A season-long group learning process in which farmers observe, experiment and decide together in their own fields. It builds problem-solving capacity rather than simply transferring a recommended package.

A small, visible field trial comparing a recommended practice with local practice under farm conditions. It gives farmers and advisers shared evidence and a meeting point for discussion.

A farming system built on minimum soil disturbance, permanent soil cover and diverse crop sequences. It reduces erosion and conserves moisture, but often needs different weed and fertiliser management.

The decomposed and decomposing plant and animal material in soil. It holds nutrients and water, supports soil structure and feeds soil organisms, and declines quickly when residues are removed or soil is over-cultivated.

The proportion of applied fertiliser nutrient taken up by the crop, or the yield produced per kilogram of nutrient applied. Low efficiency signals losses to leaching, volatilisation or erosion that cost money and pollute.