PEC EPE Agricultural key terms

Mechanical manipulation of soil to prepare a seedbed, control weeds, or manage residue. Primary tillage breaks compacted layers; secondary tillage refines the surface. Depth, timing, and intensity determine fuel use, moisture loss, and erosion risk.

Any tillage and planting system leaving at least 30 percent of the soil surface covered by crop residue after planting. It reduces erosion and runoff but can slow soil warming and complicate pest control compared with clean tillage.

A planting system where the seed is placed directly into undisturbed soil, with no prior tillage except possibly a narrow seed slot. Residue stays on the surface, conserving moisture and soil, but residue management and seed placement accuracy become critical.

The horizontal force a tillage implement requires to move through soil. It depends on soil type, moisture, depth, speed, and tool geometry. Draft determines tractor power needs and fuel consumption for field operations.

Reduction of soil pore space caused by pressure from wheels, tillage tools, or livestock. It increases bulk density, restricts root growth and water infiltration, and raises draft. Axle load and soil moisture at the time of traffic drive severity.

A system confining all wheel traffic to permanent, defined lanes so most of the field is never compacted. It requires matching machinery working widths and improves infiltration, root growth, and traction where lanes are used.

Plant material left on the field after harvest, such as stalks, straw, and stubble. Residue shields soil from raindrop impact, reduces evaporation, and adds organic matter, but heavy amounts can block planters and harbor pests.

An implement that opens a furrow, meters seed at a controlled rate, places it at a uniform depth, and covers it. Row spacing, metering accuracy, and depth control determine emergence uniformity and final stand.

A machine that places individual seeds at precise spacing within rows, often with fertilizer and pesticide attachments. Singulation accuracy, downforce, and closing systems strongly affect emergence and yield in row crops such as maize and soybean.

The mechanism controlling how many seeds are released per unit of travel. Common types include fluted rollers, finger pickups, and vacuum discs. Metering accuracy sets plant population and seed cost, and errors compound across a field.

A splined shaft delivering engine power to implements such as mowers, balers, and sprayers. Standard rotational speeds and shaft dimensions allow interchangeability. Correct shielding and matching of implement power demand prevent driveline failure and injury.

A tractor linkage with two lower arms and one upper link that mounts and lifts implements. It transfers draft and controls working depth. Category sizing must match implement load to avoid damage or loss of control.

Deciding when and how much to irrigate based on crop water demand, soil moisture status, and weather. Good scheduling avoids both yield loss from stress and waste from over-irrigation, leaching, and runoff.

Combined water loss from soil and plant surfaces by evaporation and from plants by transpiration. Reference values are adjusted by a crop coefficient to estimate field demand, which sets the basis for irrigation scheduling.

The amount of water a soil can retain and make available to plants, governed mainly by texture and organic matter. Sandy soils hold little; clay loams hold more. It determines irrigation interval and drought resilience.

A system delivering water slowly through emitters near the plant root zone. It saves water and limits foliar disease, but emitters clog and the tubing and filtration add capital and maintenance cost.

Applying soluble fertilizer through an irrigation system. It delivers nutrients uniformly with water and allows in-season adjustment, but requires compatible fertilizers, careful injection rates, and backflow prevention to protect water sources.

Measuring and adjusting a sprayer so it applies the intended volume per area. It involves nozzle flow rate, travel speed, and effective swath width. Miscalibration causes underdosing, crop injury, or illegal residues and wasted chemical.

Choosing spray tips that produce the required flow rate and droplet spectrum for a given target and label. Fine droplets improve coverage but drift more; coarse droplets reduce drift but may reduce penetration and retention.

Off-target movement of pesticide droplets or vapor beyond the application area. It is influenced by droplet size, wind, boom height, and volatility. It causes crop damage, environmental contamination, and legal liability.

A decision framework combining monitoring, thresholds, cultural and biological controls, and judicious pesticide use. The aim is economic suppression of pests with the least harm to beneficial organisms, human health, and the environment.

The pest population level at which the cost of control equals the value of crop loss avoided. It guides whether to treat, preventing unnecessary sprays while avoiding economic damage from delayed action.

The mass of water in grain expressed as a percentage of total mass. It governs safe storage life, drying cost, and market grade. Grain above safe limits heats, molds, and loses value quickly.

Removing moisture from harvested grain using heated or unheated air to reach a safe storage level. Drying rate and temperature affect grain quality, cracking, and energy cost. Over-drying wastes energy and weight.

Moving ambient air through a grain mass to cool it and equalize temperature. Cooling slows mold growth and insect activity without removing much moisture. Fans are run when outside air is cooler and drier than the grain.

A machine that cuts, threshes, separates, and cleans grain in one pass. Settings for cylinder speed, concave clearance, and fan flow must match the crop to limit grain loss and damage.

Grain left in straw or chaff or lost from the machine during harvest, expressed as a percentage of yield. Excessive speed or poor adjustment increases loss. Measuring loss helps optimize combine settings.

Compressing harvested forage or straw into bound packages for handling and storage. Bale type, moisture at baling, and density affect drying, spoilage risk, and transport cost. Wet forage can heat and combust in storage.

The nutritional value of feed, reflected in digestibility, protein, fiber, and energy content. It declines as plants mature. Harvest timing is the most powerful management lever for quality in hay and silage.

Fermented, high-moisture forage preserved in anaerobic conditions. Lactic acid bacteria lower pH and suppress spoilage. Success depends on rapid filling, good packing, and airtight sealing.

The daily volume of water an animal needs, varying with species, weight, production level, and temperature. Underestimating it limits intake, growth, and milk yield, so supply and flow rate must be designed for peak demand.

Controlled exchange of air in livestock buildings to remove heat, moisture, gases, and dust. Insufficient ventilation raises ammonia and respiratory disease; excessive airflow in cold weather chills animals and wastes energy.

Managing fields at fine spatial scale using positioning, sensors, and variable-rate technology. It matches inputs to local need, improving efficiency and reducing waste, but requires reliable data, calibration, and interpretation.

Applying seed, fertilizer, or pesticide at rates that change across a field according to a prescription map. It targets inputs where returns are highest, but depends on accurate maps and properly calibrated controllers.

Sensors on a harvester that record grain flow and moisture with position to produce yield maps. Calibration is essential; uncalibrated data misleads management decisions and undermines precision agriculture investments.

Observing crops and soil from satellites, aircraft, or drones using reflected or emitted radiation. Vegetation indices reveal variability in vigor and moisture, supporting scouting and management, though cloud cover and resolution limit usefulness.

Practices and guards that prevent injury from tractors, implements, and moving parts. Key controls include power take-off shielding, rollover protection, safe hitching, and shutting down before clearing blockages or servicing equipment.

A frame or cab on a tractor that protects the operator if the machine overturns. It is effective only when the operator wears a seat belt; without restraint, the structure can itself cause injury during a rollover.