Basic Agricultural Engineering interview questions

150 questions with answers (AGR-001 to AGR-150). Try each one aloud before reading the answer.

Soil Mechanics & Soil Science for Agriculture

AGR-001 · What are the main soil types by texture, and which is best for crops?

Sandy, silty, clay and loamy soils. Loam, a balanced mix of sand, silt and clay, is generally best because it drains well while still holding enough water and nutrients.

AGR-002 · What are the USDA particle size limits for sand, silt and clay?

Sand is 2–0.05 mm, silt is 0.05–0.002 mm and clay is finer than 0.002 mm. Particles larger than 2 mm are gravel and are excluded from texture analysis.

AGR-003 · What is soil texture and how is it classified?

Soil texture is the relative percentage of sand, silt and clay in the fine-earth fraction. It is classified with the USDA textural triangle into 12 classes such as sandy loam, clay loam and silty clay.

AGR-004 · What is soil structure?

Soil structure is the arrangement of primary particles into aggregates called peds. Common types are granular, blocky, platy, prismatic and columnar. Good granular structure improves aeration, infiltration and root growth.

AGR-005 · What is bulk density of soil?

Bulk density is the oven-dry mass of soil divided by its total volume, including pores: ρb = Ms/Vt. Mineral soils typically range from 1.1 to 1.6 g/cm³. Higher values indicate compaction.

AGR-006 · What is particle density of soil?

Particle density is the mass of soil solids per unit volume of solids alone, excluding pores. For most mineral soils it is about 2.65 g/cm³, close to that of quartz.

AGR-007 · What is soil porosity and how is it calculated?

Porosity is the fraction of soil volume occupied by pores: n = 1 − ρb/ρs. Typical agricultural soils have 40–60% porosity, with clays usually higher than sands.

AGR-008 · What is field capacity?

Field capacity is the water content a soil holds after gravitational water has drained, usually 1–3 days after saturation. It corresponds to a matric suction of about 1/3 bar (33 kPa) for most soils.

AGR-009 · What is the permanent wilting point?

It is the soil water content at which plants wilt and do not recover even in a humid atmosphere. It corresponds to a suction of about 15 bar (1500 kPa).

AGR-010 · What is available water capacity?

Available water capacity is the water held between field capacity and permanent wilting point. It is the water plants can extract, and is highest in loams and silt loams.

AGR-011 · What is soil pH and what range suits most crops?

Soil pH is the negative logarithm of hydrogen ion activity in the soil solution. Most crops grow best between 6.0 and 7.5. Acidic soils are corrected with lime and alkaline (sodic) soils with gypsum.

AGR-012 · What is cation exchange capacity (CEC)?

CEC is the total amount of exchangeable cations a soil can hold on clay and organic matter surfaces, expressed in cmol(+)/kg or meq/100 g. Higher CEC means better nutrient retention.

AGR-013 · What is soil compaction?

Soil compaction is the reduction of pore space and increase in bulk density caused by loads from machinery, animals or tillage. It restricts root growth, infiltration and aeration.

Soil & Water Conservation

AGR-014 · What is soil erosion?

Soil erosion is the detachment and removal of topsoil by water or wind. It removes the most fertile layer, lowers productivity and causes sedimentation of reservoirs and channels.

AGR-015 · What are the types of water erosion?

Splash (raindrop) erosion, sheet erosion, rill erosion, gully erosion and stream bank erosion. They progress from detachment by raindrops to concentrated flow cutting deep channels.

AGR-016 · How do soil particles move during wind erosion?

By saltation (bouncing particles about 0.1–0.5 mm), suspension (fine dust carried long distances) and surface creep (larger particles rolled along the surface). Saltation accounts for most of the movement.

AGR-017 · What is contour farming?

Contour farming is ploughing, sowing and other operations across the slope along contour lines. Each furrow and crop row acts as a small barrier that slows runoff and increases infiltration.

AGR-018 · What is strip cropping?

Strip cropping is growing alternate strips of erosion-permitting crops (such as maize) and erosion-resisting close-growing crops (such as legumes or grasses). The dense strips slow runoff and trap sediment.

AGR-019 · What is terracing?

Terracing converts a slope into a series of level or nearly level steps or broad embankments. Bench terraces suit steep slopes, while broad-based terraces suit gentle, cultivated slopes.

AGR-020 · What is a contour bund?

A contour bund is an earthen embankment built along the contour to hold runoff and let it infiltrate. It suits low-rainfall areas with permeable soils and slopes of about 2–6%.

AGR-021 · What is a graded bund?

A graded bund is built with a small longitudinal gradient so excess runoff drains safely to a waterway. It is used in higher-rainfall areas or in less permeable soils where water would otherwise pond.

AGR-022 · What is the Universal Soil Loss Equation (USLE)?

USLE estimates average annual soil loss: A = R × K × LS × C × P. R is rainfall erosivity, K soil erodibility, LS slope length-steepness, C cover-management and P the support-practice factor.

AGR-023 · What is a check dam?

A check dam is a small barrier of stone, earth, brushwood or masonry built across a gully or stream. It reduces flow velocity, traps sediment and improves groundwater recharge.

AGR-024 · What is a grassed waterway?

A grassed waterway is a broad, shallow channel with dense grass cover that carries runoff safely from fields or terraces to an outlet without causing gully erosion.

AGR-025 · What is surface runoff?

Surface runoff is the part of precipitation that flows over the land surface because rainfall intensity exceeds infiltration capacity or the soil is saturated. It carries eroded soil and nutrients.

AGR-026 · What is a shelterbelt?

A shelterbelt is a belt of trees and shrubs planted across the prevailing wind. It reduces wind speed, wind erosion and evaporation over a leeward distance of several times the tree height.

Irrigation Engineering

AGR-027 · What are the main methods of irrigation?

Surface irrigation (flood, basin, border, furrow), sprinkler irrigation and drip (trickle) irrigation. Subsurface irrigation is also used where a shallow water table can be controlled.

AGR-028 · What is irrigation?

Irrigation is the artificial application of water to soil to supply crop water needs when rainfall is insufficient or unreliable. It also helps leach salts and protect crops from frost.

AGR-029 · What is drip irrigation?

Drip irrigation delivers water slowly, at a few litres per hour, through emitters placed at or near the root zone. It wets only part of the soil and minimises evaporation and deep percolation.

AGR-030 · What is sprinkler irrigation?

Sprinkler irrigation sprays pressurised water into the air through nozzles so it falls on the crop and soil like rain. It suits undulating land and light, sandy soils.

AGR-031 · What is furrow irrigation?

Water flows in small channels (furrows) between crop ridges and infiltrates sideways and downwards. It suits row crops such as maize, cotton, sugarcane and vegetables.

AGR-032 · What is border irrigation?

The field is divided into long, gently sloping strips separated by low ridges. Water released at the upper end advances down the strip as a sheet. It suits close-growing crops like wheat and fodder.

AGR-033 · What is basin (check basin) irrigation?

The field is divided into level plots surrounded by bunds, and each plot is filled with water. It suits level land, rice and orchards, where water can pond around trees.

AGR-034 · What is duty of water?

Duty is the area that can be irrigated by a unit discharge flowing continuously over the base period of a crop. It is expressed in hectares per cumec (ha per m³/s).

AGR-035 · What is delta in irrigation?

Delta (Δ) is the total depth of water a crop needs over its entire base period, from first watering to the last. For example, rice needs far more delta than wheat.

AGR-036 · What is the base period of a crop?

The base period is the time between the first and last watering of a crop before harvest. It is usually a little shorter than the full crop period, which runs from sowing to harvest.

AGR-037 · What is consumptive use of water?

Consumptive use is the water lost by evaporation from soil and transpiration from plants, plus the small amount retained in plant tissue. In practice it is taken as equal to crop evapotranspiration.

AGR-038 · What is the difference between gross command area and culturable command area?

Gross command area (GCA) is the total area a canal can irrigate. Culturable command area (CCA) is GCA minus unculturable land such as roads, villages, ponds and barren land.

Drainage Engineering

AGR-039 · What is agricultural drainage?

Agricultural drainage is the removal of excess surface water and lowering of a high water table from the root zone. It provides aeration, allows timely field operations and controls salinity.

AGR-040 · What is the difference between surface and subsurface drainage?

Surface drainage removes excess water from the land surface through land shaping and open ditches. Subsurface drainage lowers the water table using buried pipes, mole drains or wells.

AGR-041 · What is waterlogging?

Waterlogging is a condition where the water table rises into the root zone and the soil stays saturated. Roots lack oxygen, crops yellow and yields drop, and salts often accumulate.

AGR-042 · What are the main causes of waterlogging?

Seepage from canals, over-irrigation, poor natural drainage, flat topography, impervious subsoil layers, obstruction of natural drainage by roads or embankments, and heavy rainfall.

AGR-043 · What is a tile drain?

A tile drain is a buried perforated pipe, originally short clay or concrete tiles and now usually corrugated plastic, that collects excess groundwater and carries it to an outlet.

AGR-044 · What is a mole drain?

A mole drain is an unlined cylindrical channel formed in clay subsoil by pulling a bullet-shaped mole plough. It is a cheap, temporary subsurface drain that lasts a few years in stable clays.

AGR-045 · What is an open ditch drain?

An open ditch is an excavated channel that collects surface runoff and seepage. It is cheap and has large capacity, but it occupies land, hinders machinery and needs regular weed and silt removal.

AGR-046 · What is the drainage coefficient?

The drainage coefficient is the depth of water to be removed from the drained area in 24 hours, expressed in mm/day or cm/day. It sets the required capacity of drains.

AGR-047 · What is vertical drainage?

Vertical drainage lowers the water table by pumping groundwater from tubewells. It suits areas with good-quality groundwater and permeable aquifers, and the pumped water can be reused for irrigation.

AGR-048 · What is bio-drainage?

Bio-drainage uses deep-rooted, high-transpiring trees such as eucalyptus to extract groundwater and lower the water table. It is low-cost and produces no effluent, but it acts slowly.

AGR-049 · What is a saline soil?

A saline soil has excess soluble salts: ECe above 4 dS/m, exchangeable sodium percentage (ESP) below 15 and pH usually below 8.5. A white salt crust often forms on the surface.

AGR-050 · What is a sodic (alkali) soil?

A sodic soil has ESP above 15, pH usually above 8.5 and ECe below 4 dS/m. The excess sodium disperses clay, so the soil becomes sticky when wet, hard when dry and poorly permeable.

Farm Power & Tractors

AGR-051 · What is a tractor PTO?

The power take-off (PTO) is a splined shaft, usually at the rear of the tractor, that transfers engine power to implements such as rotavators, threshers and pumps. Standard speeds are 540 and 1000 rpm.

AGR-052 · What are the sources of farm power?

Human power, animal (draught) power, mechanical power (tractors, power tillers, engines), electrical power and renewable sources such as solar, wind and biomass.

AGR-053 · What is a power tiller?

A power tiller is a single-axle, two-wheel walking tractor, usually 8–15 hp, steered by handles. It suits small farms, wet paddy fields and hilly terrain, and can run a rotary tiller or trailer.

AGR-054 · What are the main systems of a tractor?

Engine, clutch, transmission (gearbox, differential, final drive), hydraulic and hitch system, steering, brakes, PTO, wheels and tyres, and the electrical system.

AGR-055 · What is drawbar power?

Drawbar power is the power available at the drawbar for pulling implements: P = drawbar pull × forward speed. It is always less than engine power because of transmission losses, wheel slip and rolling resistance.

AGR-056 · What is a three-point linkage?

It is the standard hitch with two lower links and one upper (top) link, raised and lowered by the tractor hydraulics. It lets mounted implements be carried, lifted and controlled for depth.

AGR-057 · What is the function of the differential in a tractor?

The differential lets the two rear wheels turn at different speeds while turning, so the outer wheel can travel farther than the inner one without slipping or straining the axle.

AGR-058 · What is a differential lock?

A differential lock locks both rear axles together so they turn at the same speed. It is used when one wheel slips in mud or soft soil, and must be disengaged before turning.

AGR-059 · What is ballasting of a tractor?

Ballasting is adding weight, such as cast-iron weights or water in the tyres, to increase traction and reduce wheel slip. It also improves front-end stability when heavy rear-mounted implements are used.

AGR-060 · Why are diesel engines preferred for tractors?

Diesel (compression-ignition) engines give higher torque at low speed, better fuel efficiency, longer life and lower fire risk than petrol (spark-ignition) engines, which suits heavy, continuous field work.

AGR-061 · What is the difference between 2WD and 4WD tractors?

A 2WD tractor drives only the rear wheels. A 4WD (or MFWD) tractor also drives the front wheels, giving better traction, less slip and better performance in wet or heavy soils, at higher cost.

AGR-062 · What is wheel slip?

Wheel slip is the loss of forward travel compared with the theoretical travel of the driving wheels: s = (1 − actual speed/theoretical speed) × 100%. Some slip is unavoidable when pulling a load.

AGR-063 · How much power can a human and a bullock sustain?

A human worker can sustain roughly 0.1 hp (about 75 W) over a working day. An average bullock develops roughly 0.5 hp, depending on breed, body weight and conditions.

Farm Machinery & Implements

AGR-064 · What is a combine harvester?

A combine harvester reaps, threshes, separates and cleans grain in one pass. Its main units are the header, threshing cylinder and concave, separating unit (straw walkers or rotor), cleaning sieves with a fan, and grain tank.

AGR-065 · What is the difference between primary and secondary tillage?

Primary tillage is the first deep cutting and inversion of soil after harvest, using ploughs. Secondary tillage is the shallower work that follows to prepare a fine seedbed, using harrows, cultivators and planks.

AGR-066 · What is a mouldboard plough?

A mouldboard plough cuts a furrow slice with a share and lifts, turns and inverts it with a curved mouldboard. It buries weeds and residue well. Its main parts are the share, mouldboard, landside and frog.

AGR-067 · What is a disc plough?

A disc plough uses large concave rotating discs to cut and partly invert soil. It works better than a mouldboard plough in hard, dry, sticky, stony or root-infested soils because the discs roll over obstacles.

AGR-068 · What is a disc harrow?

A disc harrow has gangs of concave discs on a common axle, set at an angle to the direction of travel. It is used for secondary tillage, breaking clods, cutting residue and mixing soil.

AGR-069 · What is a cultivator?

A cultivator is a secondary tillage implement with rigid or spring-loaded tines and shovels or sweeps. It loosens soil, breaks clods and controls weeds before sowing or between crop rows.

AGR-070 · What is the difference between a seed drill and a planter?

A seed drill places seeds continuously in rows at a set rate, as for wheat. A planter places individual seeds at precise spacing within the row, as for maize, cotton and soybean.

AGR-071 · What is a rotavator?

A rotavator (rotary tiller) is a PTO-driven implement with L- or C-shaped blades on a rotating shaft. It cuts and mixes soil to give a fine seedbed in one or two passes.

AGR-072 · What is a seed-cum-fertilizer drill?

It is a seed drill with separate seed and fertilizer boxes and metering units. Seed and fertilizer are placed in rows at controlled rates and depths in one operation.

AGR-073 · What is a thresher?

A thresher detaches grain from the earhead or panicle by impact and rubbing, then separates and cleans it using sieves and a blower. Common types are spike-tooth, rasp-bar, hammer-mill and axial-flow threshers.

AGR-074 · What is a reaper and a reaper-binder?

A reaper cuts the crop with a reciprocating cutter bar and lays it in a windrow. A reaper-binder also gathers the cut crop into bundles and ties them with twine.

AGR-075 · What is the difference between theoretical and effective field capacity?

Theoretical field capacity is the rate of coverage at full width and speed with no lost time: width × speed. Effective field capacity is the actual rate after turning, overlap and adjustment losses. Their ratio is field efficiency.

Post-Harvest Engineering

AGR-076 · What is post-harvest engineering?

Post-harvest engineering applies engineering to the handling, threshing, cleaning, drying, storage, processing, packaging and transport of produce after harvest. Its aims are to reduce losses, keep quality and add value.

AGR-077 · What is threshing?

Threshing is the separation of grain from the earhead, panicle or pod by impact, rubbing or treading. It can be done manually, by animals or with mechanical threshers.

AGR-078 · What is winnowing?

Winnowing separates grain from chaff, straw and light impurities using an air stream, from natural wind or a fan. It relies on differences in terminal velocity between grain and impurities.

AGR-079 · What is the difference between wet basis and dry basis moisture content?

Wet basis: Mw = water mass/total mass × 100. Dry basis: Md = water mass/dry matter mass × 100. Dry basis values are always higher. Trade and storage usually use wet basis.

AGR-080 · What is the safe storage moisture content for cereal grains?

For most cereals it is about 12–14% wet basis, lower for long-term storage and for seed. Above this, mould growth, insect activity and heating increase rapidly.

AGR-081 · What is grain drying?

Grain drying removes moisture from harvested grain down to a safe storage level by moving heated or unheated air through it. Heat evaporates the water and the air carries the vapour away.

AGR-082 · What is equilibrium moisture content (EMC)?

EMC is the moisture content a hygroscopic material reaches after long exposure to air at a given temperature and relative humidity. At EMC there is no net moisture exchange.

AGR-083 · What is parboiling of paddy?

Parboiling is soaking, steaming and drying paddy before milling. It gelatinises the starch, which reduces breakage during milling, raises head rice yield and moves some vitamins from the bran into the grain.

AGR-084 · What are the main steps in rice milling?

Cleaning, dehusking (hulling), separating husk and paddy, whitening (polishing) to remove bran, and grading. Husk is about 20% of paddy weight, and milled rice is typically 65–70%.

AGR-085 · What is grading of agricultural produce?

Grading sorts produce into classes based on size, shape, colour, weight, density or quality. It improves market value and uniformity, and is done with screens, rollers, weight graders or optical sorters.

AGR-086 · What is dal milling?

Dal milling removes the husk (seed coat) of pulses and splits the cotyledons into two halves (dal). It involves pre-treatment (oil/water or dry method), dehulling, splitting, and separation by sieving and aspiration.

AGR-087 · What is a hygroscopic material?

A hygroscopic material absorbs or releases moisture from the surrounding air until it reaches equilibrium. Grains, seeds, flour and dried fruits are hygroscopic, so storage humidity must be controlled.

AGR-088 · What is the difference between sun drying and mechanical drying?

Sun drying spreads produce in the open. It is cheap but slow, weather-dependent and prone to contamination and losses. Mechanical drying uses fans and heaters for faster, controlled, hygienic drying, at a cost in energy and equipment.

Storage Structures & Agricultural Processing

AGR-089 · Why is scientific grain storage needed?

It protects grain from moisture, insects, rodents, birds and moulds, which keeps quality and germination intact. It also lets food be supplied all year round and stabilises prices.

AGR-090 · What is the difference between bag storage and bulk storage?

Bag storage keeps grain in jute or plastic bags stacked in godowns, which is flexible but labour-intensive. Bulk storage holds loose grain in bins or silos, which allows mechanised handling, aeration and lower cost per tonne.

AGR-091 · What is a silo?

A silo is a tall cylindrical or rectangular structure of steel or concrete for bulk storage of grain or silage. It usually has mechanical loading, unloading, aeration and temperature monitoring.

AGR-092 · What are traditional grain storage structures in India?

Examples are kothi (wooden or mud bins), bukhari and morai (bamboo or straw structures), kanaja (bamboo baskets), mud bins and underground pits. They are cheap but often not airtight or rodent-proof.

AGR-093 · What is CAP storage?

Cover and Plinth (CAP) storage stacks bagged grain on raised plinths with wooden crates and covers it with polythene sheets. It is used as low-cost open storage by agencies such as the FCI.

AGR-094 · What is a warehouse?

A warehouse is a scientifically built storage godown with damp-proof floors, rodent-proof design and provision for fumigation. Warehousing also issues receipts that farmers can use to raise credit.

AGR-095 · At what conditions are table potatoes stored in cold storage?

Table and seed potatoes are commonly stored at about 2–4 °C with 90–95% relative humidity. This suppresses sprouting and reduces weight loss and disease.

AGR-096 · What is controlled atmosphere (CA) storage?

CA storage keeps produce in airtight rooms where O₂ is reduced, CO₂ is raised and temperature and humidity are tightly controlled. Slower respiration greatly extends the storage life of fruits such as apples.

AGR-097 · What is fumigation of stored grain?

Fumigation releases a toxic gas, such as phosphine from aluminium phosphide, into a sealed stack or structure to kill all insect stages. Gas-tight sealing and an adequate exposure time are essential.

AGR-098 · What is hermetic storage?

Hermetic storage keeps grain in airtight bags or containers. Respiration by grain and insects uses up O₂ and builds up CO₂, which kills insects and stops mould without chemicals.

AGR-099 · What are unit operations in agricultural processing?

Basic steps common to many processes: cleaning, sorting and grading, size reduction, mixing, separation, drying, evaporation, heating, cooling, conveying and packaging.

AGR-100 · What is size reduction?

Size reduction breaks solid materials into smaller pieces by compression, impact, shear or attrition, as in grinding grain into flour. Common equipment includes hammer mills, plate (burr) mills, roller mills and pin mills.

Dairy & Food Engineering Basics

AGR-101 · What is pasteurisation of milk?

Pasteurisation heats milk to destroy pathogens and most spoilage organisms without significantly changing taste. HTST heats to 72 °C for 15 s. LTLT (batch) heats to 63 °C for 30 min. The milk is then cooled quickly.

AGR-102 · What is UHT treatment?

Ultra-high temperature treatment heats milk to about 135–150 °C for a few seconds and then packs it aseptically. The product is commercially sterile and keeps for months at room temperature until opened.

AGR-103 · What is homogenisation of milk?

Homogenisation forces milk at high pressure through a narrow valve to break fat globules to about 1–2 µm. This prevents cream from rising and gives a uniform texture.

AGR-104 · On what principle does a cream separator work?

Centrifugal force. In a rapidly rotating bowl with a stack of discs, the heavier skim milk moves outward and the lighter fat globules (cream) move toward the centre, so they leave through separate outlets.

AGR-105 · What is the approximate composition of cow milk?

About 87% water, 3.5–4.5% fat, 3.2–3.5% protein (mainly casein), 4.7–4.9% lactose and 0.7% ash. Buffalo milk has higher fat, typically 6–8%.

AGR-106 · What is the difference between pasteurisation and sterilisation?

Pasteurisation kills pathogens and most vegetative microbes, so the product needs refrigeration and has a short shelf life. Sterilisation (or commercial sterility) also destroys heat-resistant spores, giving a shelf-stable product.

AGR-107 · What is a bulk milk cooler?

A bulk milk cooler is an insulated stainless steel tank with refrigeration and an agitator. It cools milk to about 4 °C quickly after milking at village collection centres, which controls bacterial growth.

AGR-108 · What is CIP in dairy plants?

Clean-in-place (CIP) cleans pipelines, tanks and heat exchangers without dismantling them. Rinse water, alkali and acid solutions are circulated in sequence at set temperature, concentration, flow and time.

AGR-109 · What is a plate heat exchanger (PHE)?

A PHE is a stack of thin corrugated stainless steel plates with alternate channels for product and heating or cooling medium. It gives high heat transfer in a compact unit and is standard in milk pasteurisers.

AGR-110 · What is spray drying?

Spray drying atomises a liquid concentrate into a chamber of hot air. The fine droplets dry in seconds into powder. It is used for milk powder, coffee and many food ingredients.

AGR-111 · What is evaporation in food processing?

Evaporation concentrates liquid foods by boiling off part of the water, usually under vacuum to lower the boiling temperature. It is used for condensed milk, juice concentrates and as a step before spray drying.

AGR-112 · What is water activity (aw)?

Water activity is the ratio of the vapour pressure of water in a food to that of pure water at the same temperature. Most bacteria need aw above about 0.91. Low aw improves shelf stability.

AGR-113 · What is blanching?

Blanching is a brief heat treatment of vegetables or fruits in hot water or steam before freezing, canning or drying. It inactivates enzymes, reduces microbes, removes air and helps retain colour.

Renewable Energy in Agriculture

AGR-114 · What is the composition of biogas?

Biogas is mainly methane (about 55–65%) and carbon dioxide (about 35–45%), with traces of hydrogen sulphide, water vapour and nitrogen. Methane is the combustible part.

AGR-115 · What are the main types of family biogas plants in India?

The floating-drum type (KVIC model), where a steel gas holder rises and falls, and the fixed-dome type (Janata, Deenbandhu), where gas is stored under a brick or concrete dome and pressure varies.

AGR-116 · What is biomass gasification?

Gasification is partial combustion of biomass with limited air at high temperature to produce producer gas, which is mainly CO, H₂, CH₄ and N₂. The gas can fuel engines, generate electricity or provide process heat.

AGR-117 · What is a solar dryer?

A solar dryer uses solar collectors to heat air that passes over produce in an enclosed chamber. It dries faster and more hygienically than open sun drying. Types include cabinet, tunnel and greenhouse dryers.

AGR-118 · What is a solar water pump?

A solar pump uses photovoltaic panels to drive a DC or AC motor-pump set (through a controller or inverter) to lift water for irrigation. It needs no diesel or grid power, and pumping follows sunlight.

AGR-119 · What is biomass briquetting?

Briquetting compresses loose agricultural residues such as rice husk, sawdust and straw into dense blocks or pellets. They are easier to store, transport and burn as fuel.

AGR-120 · What is a windmill used for in agriculture?

Windmills convert wind energy into mechanical power to drive reciprocating pumps that lift water from wells. Wind turbines can also generate electricity. They suit areas with steady winds.

AGR-121 · What is the photovoltaic effect?

The photovoltaic effect is the generation of voltage and current in a semiconductor junction, typically silicon, when it absorbs light. Photons free electrons, which are then separated by the junction's electric field.

AGR-122 · What are biofuels?

Biofuels are fuels made from biomass. Examples are bioethanol (from sugarcane, molasses, grains), biodiesel (from vegetable oils by transesterification), biogas and bio-CNG. They can partly replace fossil fuels.

AGR-123 · What is agrivoltaics?

Agrivoltaics uses the same land for crop production and solar PV generation, with panels raised or spaced above crops. It increases total land productivity and can reduce crop heat stress and evaporation.

AGR-124 · What is biogas slurry and how is it used?

Biogas slurry is the digested effluent leaving a biogas plant. It is a good organic manure containing nitrogen, phosphorus and potassium, and it is applied to fields directly or after composting.

AGR-125 · What is hydraulic retention time (HRT) in a biogas plant?

HRT is the average time the slurry stays in the digester: HRT = digester volume/daily feed volume. For cattle dung plants it is typically 30–55 days depending on climate.

Precision Agriculture & Remote Sensing

AGR-126 · What is remote sensing?

Remote sensing collects information about the Earth's surface without contact, by measuring reflected or emitted electromagnetic radiation with sensors on satellites, aircraft or drones.

AGR-127 · What is GIS?

A Geographic Information System captures, stores, analyses and displays spatially referenced data in layers such as soil, crops and yield. It is used to map fields and plan management.

AGR-128 · What is GNSS and how is it used on farms?

GNSS (Global Navigation Satellite System) includes GPS, GLONASS, Galileo, BeiDou and India's NavIC. It gives the position of tractors, samplers and yield monitors so data and operations can be georeferenced.

AGR-129 · What is RTK-GNSS?

Real-time kinematic GNSS uses carrier-phase measurements and corrections from a nearby base station to give centimetre-level positioning in real time. It is used for auto-steering, controlled traffic and precise planting.

AGR-130 · What is a spectral signature?

A spectral signature is the characteristic pattern of reflectance of a surface across wavelengths. Healthy vegetation has low red reflectance and high near-infrared reflectance, unlike soil or water.

AGR-131 · What is the difference between active and passive remote sensing?

Passive sensors record natural radiation that is reflected sunlight or emitted heat, as in optical and thermal imaging. Active sensors emit their own energy and record the return, as in radar (SAR) and LiDAR.

AGR-132 · What is spatial resolution?

Spatial resolution is the size of the smallest ground area represented by one pixel, such as 10 m or 30 m. Finer resolution shows more detail within a field.

AGR-133 · What is a yield monitor?

A yield monitor on a combine measures grain flow and moisture continuously and links them to GNSS position. It produces yield maps that show spatial variation within a field.

AGR-134 · What is variable rate technology (VRT)?

VRT applies inputs such as seed, fertilizer, pesticide or water at different rates across a field according to need, using prescription maps or real-time sensors and controllers.

AGR-135 · How are drones used in agriculture?

Drones (UAVs) carry RGB, multispectral or thermal cameras to monitor crops, map fields and detect stress. They are also used to spray pesticides and nutrients on small and hard-to-reach fields.

AGR-136 · What sensors are used to measure soil moisture?

Tensiometers (measure matric suction), gypsum blocks, time domain reflectometry (TDR), capacitance (FDR) probes and neutron probes. The gravimetric oven-drying method is the reference standard.

AGR-137 · What is auto-steering in tractors?

Auto-steering uses GNSS receivers, often RTK, and a steering actuator to guide the tractor along planned paths automatically. It reduces overlap, operator fatigue and input waste.

AGR-138 · What is the difference between multispectral and hyperspectral imaging?

Multispectral sensors record a few broad bands, typically 3–10, such as blue, green, red, red-edge and NIR. Hyperspectral sensors record hundreds of narrow, contiguous bands, which allows finer detection of crop stress, disease and nutrients.

Greenhouse Technology & Watershed Management

AGR-139 · How does a greenhouse trap heat?

The glazing lets most incoming shortwave solar radiation through, but it partly blocks outgoing longwave (infrared) radiation from the warmed interior. It also stops warm air escaping by convection, so the inside stays warmer than outside.

AGR-140 · What glazing materials are used for greenhouses?

Glass, UV-stabilised polyethylene film (commonly 200 micron), polycarbonate sheets, acrylic and fibreglass-reinforced plastic. Polyethylene is cheapest and most common in India.

AGR-141 · What are common greenhouse shapes?

Even-span, uneven-span, ridge-and-furrow (gutter-connected), sawtooth, Quonset (hoop), gothic arch and lean-to. The choice depends on climate, ventilation needs, snow or wind loads and cost.

AGR-142 · What is a shade net house?

A shade net house is a structure covered with knitted HDPE shade netting of a set shade percentage (such as 35%, 50% or 75%). It reduces radiation and temperature, and is used for nurseries, vegetables and ornamentals.

AGR-143 · What is the difference between natural and forced ventilation in greenhouses?

Natural ventilation uses roof and side vents, relying on wind and buoyancy (stack effect). Forced ventilation uses exhaust fans for a controlled air exchange, often combined with evaporative pads.

AGR-144 · What is fan-and-pad cooling?

Exhaust fans on one wall draw outside air through wet cellulose pads on the opposite wall. Evaporation cools the air before it moves across the crop. It works best in dry climates.

AGR-145 · What is a low tunnel?

A low tunnel is a small, temporary plastic-covered hoop structure, typically under 1 m high, over crop rows. It protects early crops from cold, frost and rain and speeds growth.

AGR-146 · What is hydroponics?

Hydroponics grows plants without soil, with roots in a nutrient solution or an inert medium such as cocopeat, perlite or rockwool. Common systems are NFT, deep water culture and drip-fed substrate culture.

AGR-147 · What is watershed management?

Watershed management is the planned use of land, water and vegetation in a drainage area to conserve soil and water, improve productivity and livelihoods, and reduce floods and sedimentation, with community participation.

AGR-148 · What is the ridge-to-valley approach in watershed treatment?

Treatment starts at the upper ridge area with measures such as afforestation, contour trenches and bunds, then moves down to the valley with check dams and ponds. This controls runoff at its source and protects downstream structures.

AGR-149 · What is a farm pond?

A farm pond is a small dug-out or embankment reservoir on a farm. It collects runoff for supplemental (life-saving) irrigation, livestock and fish, and it also helps recharge groundwater.

AGR-150 · What is a percolation tank?

A percolation tank is a small reservoir built over permeable strata to hold runoff long enough for it to percolate and recharge groundwater, which raises water levels in downstream wells.

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