Tillage, sowing and harvesting machinery

In short

Tillage, sowing and harvesting machinery covers the implements that cut and loosen soil, place seed and fertiliser at a controlled depth and spacing, and cut, thresh and clean the crop. These machines decide the timeliness, energy use and yield of Indian farming, where labour scarcity has pushed custom hiring of rotavators, zero-till drills and combines. The topic is examined in GATE Agricultural Engineering (Farm Machinery and Power section), university papers on implement design and field capacity, and interviews at Mahindra, John Deere, TAFE, Escorts Kubota, VST Tillers, Sonalika, Jain Irrigation and the ICAR/CIAE-FMTTI testing network. Numerical questions centre on draft, drawbar power, field capacity, seed rate calibration and threshing losses.

Explained

Tillage: purpose, types and measures

• Tillage - mechanical manipulation of soil to create a seedbed, control weeds, incorporate residues and manage moisture. Tilth is the resulting physical condition (crumb size, porosity).
• Primary tillage: the first, deep (15-30 cm), soil-inverting or shattering operation - mouldboard plough, disc plough, subsoiler, chisel plough, rotavator (one-pass).
• Secondary tillage: shallower (5-15 cm) operations that pulverise clods, level and firm the seedbed and kill weeds - harrows, cultivators, rotary tillers, planks, levellers.
• Conservation / minimum tillage: residue retained on surface, ≥30% cover; zero tillage plants directly into untilled soil. Reduces cost, diesel and erosion; key to Happy Seeder sowing of wheat in paddy stubble (north-west India, instead of burning).
• Soil-engaging measures: draft (horizontal force to pull the implement, kN), unit draft / specific draft (draft per unit furrow cross-section, kN/m² or N/cm²), vertical and side forces, soil resistance which rises with clay content, moisture below optimum, depth and speed.
• Depth of tillage is controlled by hitch geometry and hydraulic draft/position control on the tractor; width of cut by number and spacing of bottoms or tines.

Primary tillage implements

• Mouldboard plough (MB plough): inverts a furrow slice; parts - share (cuts horizontally), mouldboard (lifts, twists, inverts), landside (takes side thrust), frog (joins parts), gunnel, shin, coulter (vertical cut), jointer and gauge wheel. Bottom types: general purpose, stubble, sod/breaker, slat, high-speed.
• Mouldboard terms: suction (vertical clearance) - downward tilt of share point; horizontal suction - side clearance; these make the plough bite and hold its line. Reversible MB plough turns furrows one way on hilly or irrigated land (no back furrow / dead furrow).
• Disc plough: concave discs (60-90 cm dia) at tilt angle (15-25° from vertical) and disc angle (42-45° from direction of travel); cuts rather than inverts fully. Best in hard, dry, stony, sticky or trashy soil and where root cutting is needed; penetrates by weight, so it is heavier per unit width and leaves a rougher surface. Vertical disc plough (one-way disc) and disc harrow-plough variants exist.
• Chisel plough / subsoiler: narrow shanks break hard pans at 40-60 cm without inverting; used for compacted sugarcane and cotton fields.
• Rotary tiller (rotavator): PTO-driven L, C or J-shaped blades on a horizontal shaft; one pass gives a seedbed, buries residue, but is power-hungry (needs 7-10 hp per foot of width) and over-use destroys soil structure and forms a tilled-layer pan.
• Puddler / cage wheel + puddling harrow: destroys structure deliberately to reduce percolation in transplanted paddy.

Secondary tillage and levelling implements

• Disc harrow: gangs of smaller discs - single-acting has two gangs end to end throwing soil in opposite directions; double-acting (tandem) throws soil out with the front gangs and back in with the rear; the offset type works to one side of the tractor, used in orchards; parameters are disc diameter, spacing, gang angle.
• Cultivator (tined harrow): rigid-tyne (tough soil, deeper) or spring-loaded shovel type (stony soil - shovels trip over obstructions); 9, 11, 13 tynes; standard in Indian wheat and cotton fields.
• Blade harrow (bakhar/guntaka), spike-tooth harrow, patela/plank, cultipacker / roller for clod crushing and compacting.
• Laser land leveller: tractor-drawn bucket with laser transmitter and receiver controlling a hydraulic valve; achieves ±2 cm levelling, saving 20-30% irrigation water - widely subsidised under SMAM/custom-hiring centres.
• Interculture: rotary weeders, wheel hoe, power weeder, ridger for earthing up.

Sowing and planting machinery

• Broadcasting - scattered seed, no control; drilling - seed in rows at set depth; dibbling/planting - single seeds at set spacing (precision planters); transplanting - raised seedlings placed in the field.
• Seed drill parts: hopper, metering mechanism, seed tube, furrow opener, covering device (chain/press wheel), ground wheel drive, frame and hitch, seed-rate adjusting lever.
• Metering mechanisms: fluted roller (common in Indian seed-cum-fertiliser drills), internal/external double run, cup feed, cell type, vertical/horizontal plate, inclined plate (for groundnut, soybean), pneumatic (air suction) for precision planters, auger/star wheel for fertiliser.
• Furrow openers: shoe (hard soil), shovel/reversible shovel, hoe type (trashy conditions, Indian drills), single and double disc (zero-till, residue), inverted-T type (zero-till drill - standard for wheat after paddy), runner.
• Seed-cum-fertiliser drill places fertiliser in a separate band below/beside the seed. Zero-till drill uses inverted-T or disc openers; Happy Seeder has a flail-type straw-management unit ahead of the openers; Super Seeder chops and incorporates straw with a rotor plus drill; Smart/Surface Seeder sows and mulches.
• Planters: ridge/bed planters, pneumatic precision planter (maize, cotton), potato planter (automatic/semi-automatic with cup belt), sugarcane cutter-planter (cuts setts, treats and places), paddy drum seeder for pre-germinated seed.
• Paddy transplanter: walk-behind (4-6 row) and riding (6-8 row, up to 10) types using mat-type nursery raised on a plastic tray; pick-up fork or rotary arm mechanism; replaces 25-30 person-days/ha of manual transplanting.
• Calibration of a seed drill - the core lab exercise: jack up the drive wheel, turn it a counted number of revolutions equal to a known area, collect and weigh seed from each spout, compute kg/ha, adjust the lever and repeat; also check spout-to-spout variation (coefficient of variation) and seed damage.

Harvesting, threshing and crop-processing machinery

• Harvesting terms: reaping (cutting), gathering, threshing (separating grain from ear), winnowing/cleaning, combining (all in one machine).
• Cutting mechanisms: cutter bar (reciprocating knife) - knife sections, ledger plates, shear bar, guards, wobble/pitman drive; rotary disc/blade; flail. Registration, register and clearance of the knife must be correct or cutting fails.
• Reaper (cuts and windrows), reaper binder (cuts and ties sheaves - vertical conveyor type, popular with 2WD tractors), mower (fodder), forage harvester, sugarcane harvester (track or wheel, base cutter + chopper + extractor fans).
• Threshers: cylinder types - spike tooth (wheat; Indian multi-crop thresher), rasp bar, hammer mill/beater, syndicator, axial flow (paddy, maize), wire loop (paddy pedal thresher). Components - feeding chute, cylinder, concave, blower/aspirator, sieves/shaker, grain outlet. Cylinder peripheral speed and cylinder-concave clearance are the two main settings; too high speed = broken grain, too low = unthreshed heads.
• Combine harvester: header (cutter bar + reel + auger), feeder conveyor, threshing cylinder and concave, straw walkers or rotary separator, cleaning shoe (sieves + fan), grain tank and unloading auger. Types - self-propelled, tractor-mounted/PTO, track-type (paddy). Must carry a Straw Management System (SMS) in Punjab/Haryana so paddy straw is spread, not burnt.
• Harvest losses: header/cutter-bar loss, shatter loss, threshing (unthreshed) loss, separation loss, cleaning (blower) loss, broken grain. Total should stay within about 2-5% for a well-set combine; measured by collecting grain from a known area behind the machine.
• Post-harvest machines in the same chain: maize dehusker-sheller, groundnut decorticator, paddy winnower, chaff cutter, straw baler (square/round).

Performance, hitching and Indian standards

• Hitching: single-point (animal-drawn), two-point, three-point linkage (two lower links + top link; per ISO 730 Category I - tractors up to about 48 hp (35 kW), Category II - about 40-100 hp (30-75 kW)); drawbar for trailed implements; virtual hitch point and centre of resistance must lie in line with the tractor's pull line to avoid side draft.
• Tractor hydraulic control: position control (fixed implement height), draft control (depth varies to hold constant draft), mixed control; a check chain limits sway.
• Field capacity and efficiency, cost of operation (fixed + variable), and break-even / custom-hiring rates are examined numerically.
• Standards and institutions (India): Bureau of Indian Standards publishes implement specifications and test codes (series on agricultural tractors and implements - quote a number only when certain, since several older IS numbers have been revised or withdrawn). Machines are tested and batch-tested at the four Farm Machinery Training and Testing Institutes (FMTTI) - the Central FMTTI at Budni (MP), Northern Region at Hisar (Haryana), Southern Region at Garladinne (Anantapur, AP) and North-Eastern Region at Biswanath Chariali (Assam); ICAR-CIAE Bhopal and the AICRP on Farm Implements and Machinery develop and evaluate designs. A valid test report is required for subsidy under SMAM / RKVY / Crop Residue Management schemes and state custom-hiring-centre programmes.
• Safety and regulation: PTO shaft guarding and thresher safety (feeding chute length, no exposed cylinder) are covered by BIS safety requirements for power threshers; the four Labour Codes in force from 21 November 2025 (replacing the Factories, Minimum Wages, Industrial Disputes and BOCW Acts) govern safety and working conditions in implement manufacturing plants. Farm machinery attracts GST at the 5% slab for most implements since the 22 September 2025 rate revision - confirm the current rate for a specific HSN, as classifications change.

Key points

• Tillage - mechanical soil manipulation to prepare a seedbed; primary = deep and inverting, secondary = shallow and pulverising.
• Mouldboard plough - inverts the furrow slice; needs vertical and horizontal suction to penetrate and track.
• Disc plough - cuts by rolling discs set at tilt and disc angles; penetrates by weight, best in hard, dry, trashy soil.
• Rotavator - PTO-driven, one-pass seedbed; highest power per unit width, risk of structure damage.
• Draft - the horizontal pull; unit draft is draft per unit furrow cross-section and rises with speed, depth and clay.
• Cultivator - rigid tyne for deeper work, spring-loaded shovel for stony soil.
• Laser land leveller - laser-controlled bucket giving ±2 cm precision and 20-30% irrigation water saving.
• Seed drill vs planter - drill gives row placement at a seed rate; planter places single seeds at set spacing.
• Fluted roller - the standard metering device in Indian seed-cum-fertiliser drills; rate changed by exposure length.
• Inverted-T opener - zero-till drill opener that sows into untilled, residue-free slots.
• Happy Seeder / Super Seeder - sow wheat into standing or chopped paddy straw, the mechanical answer to stubble burning.
• Seed drill calibration - rotate the ground wheel for a known area, weigh collected seed, compute kg/ha and adjust.
• Cutter bar - reciprocating knife with sections and ledger plates; correct registration and clearance are essential.
• Thresher cylinder - spike tooth for wheat, axial flow for paddy/maize; speed and concave clearance control grain damage.
• Combine - header, threshing, separation, cleaning and grain handling in one machine; SMS mandatory in NW India.
• Field capacity - theoretical = width × speed; effective = actual area per hour; field efficiency is their ratio, typically 65-85%.
• Three-point linkage - Category I for tractors up to about 48 hp (35 kW) and Category II for about 40-100 hp (30-75 kW).
• FMTTI Budni / Hisar / Garladinne / Biswanath Chariali - test and batch-test machines; a test report gates subsidy.

Formulas and examples

Example 1 - Draft and drawbar power of a 3-bottom MB plough. Each bottom cuts 30 cm wide at 18 cm depth; unit draft 55 kN/m²; speed 4.5 km/h.

• Furrow area per bottom = 0.30 × 0.18 = 0.054 m²; for 3 bottoms = 0.162 m².
• Draft D = 55 × 0.162 = 8.91 kN.
• Drawbar power = 8.91 × 4.5 / 3.6 = 11.14 kW (≈14.9 hp).
• If tractive efficiency is 0.70, engine power needed ≈ 11.14 / 0.70 ≈ 15.9 kW (21.3 hp) at the drawbar path, so a 35 hp tractor is adequate with reserve.

Example 2 - Field capacity and efficiency of a rotavator. Width 1.8 m, speed 3.0 km/h; it covers 3.2 ha in 8 h including turning, refuelling and blockage clearing.

• TFC = (1.8 × 3.0)/10 = 0.54 ha/h.
• EFC = 3.2/8 = 0.40 ha/h.
• Field efficiency = 0.40/0.54 × 100 = 74.1%.
• Time to till 10 ha = 10/0.40 = 25 h. At 6 l/h diesel and ₹92/l, fuel cost = 25 × 6 × 92 = ₹13,800, i.e. ₹1,380/ha for fuel alone.

Example 3 - Seed drill calibration (wheat). 9-row drill, row spacing 20 cm, ground wheel diameter 60 cm; target 100 kg/ha.

• Working width W = 9 × 0.20 = 1.8 m. Distance for 1 ha = 10000/1.8 = 5555.6 m.
• Wheel circumference = π × 0.60 = 1.885 m → revolutions for 1 ha = 5555.6/1.885 = 2947 rev.
• Run 1/50 of that = 59 rev (approximately); seed collected should be 100/50 = 2.0 kg total, i.e. 0.222 kg per spout.
• If the actual collection is 1.7 kg, the rate is 1.7 × 50 = 85 kg/ha - increase the fluted-roller exposure and recalibrate.
• Check: no spout should deviate more than about ±5% from the mean.

Example 4 - Plant population and planter check (maize). Row spacing 60 cm, plant-to-plant 20 cm.

• Population = 10000/(0.60 × 0.20) = 83,333 plants/ha.
• At 1,000-grain weight 250 g and 90% germination with 95% field establishment, seeds needed = 83,333/(0.90 × 0.95) = 97,466 → seed rate = 97,466 × 0.250/1000 = 24.4 kg/ha.

Example 5 - Thresher cylinder speed and losses. Spike-tooth cylinder 600 mm diameter running at 700 rpm; feed rate 1,200 kg/h of wheat crop giving 480 kg/h grain in the main outlet, 12 kg/h grain lost with straw, 8 kg/h unthreshed.

• Peripheral speed = π × 0.6 × 700/60 = 21.99 m/s (within the usual 20-25 m/s band for wheat; paddy needs much lower, about 12-16 m/s).
• Total grain input = 480 + 12 + 8 = 500 kg/h.
• Threshing efficiency = (500 − 8)/500 × 100 = 98.4%.
• Grain loss with straw = 12/500 × 100 = 2.4%; total loss = 20/500 = 4.0% - reduce by closing concave clearance slightly and lowering blower speed.

Where it is used

• Tractor and implement manufacturers: Mahindra & Mahindra, TAFE, Escorts Kubota, Sonalika (ITL), John Deere India, New Holland, VST Tillers Tractors, Kubota, Shaktiman, Fieldking, Landforce - design, validation and service engineering roles.
• Combine and harvester makers: Preet, Kartar, Dasmesh, Balkar, Claas India, John Deere (paddy track combines), Shaktiman sugarcane harvesters; service and field-support engineers.
• Testing and certification: FMTTI Budni (CFMTTI)/Hisar/Garladinne/Biswanath Chariali, state agricultural universities and ICAR-CIAE - test engineers running BIS test codes for commercial and batch testing.
• Custom hiring and farm-service businesses: CHCs and Farm Machinery Banks under SMAM, hi-tech hubs, aggregator platforms (Mahindra Trringo, EM3 AgriServices) - fleet, utilisation and costing roles.
• Extension and government: KVKs, state Departments of Agriculture, crop-residue-management programmes promoting Happy Seeder/Super Seeder and SMS-fitted combines in Punjab, Haryana and western UP.
• Agri-fintech and precision agriculture: telematics on tractors and implements, variable-rate drills, sensor-based depth control and GPS-guided levelling.

Interview questions

• Q: Difference between primary and secondary tillage? A: Primary tillage is the first deep operation (15-30 cm) that cuts and inverts or shatters soil; secondary tillage is shallower work that pulverises clods, levels the surface and kills weeds to finish the seedbed.
• Q: When would you choose a disc plough over a mouldboard plough? A: In hard, dry, stony, sticky or trash- and root-filled soil where an MB plough cannot penetrate or would choke; the disc rolls over obstructions and cuts roots, though it inverts the soil less completely.
• Q: What is suction in a mouldboard plough? A: The small downward tilt of the share point (vertical suction) and sideways clearance (horizontal suction) that make the bottom penetrate to depth and hold its line against side thrust.
• Q: Define unit draft and say what increases it. A: Draft per unit furrow cross-sectional area (kN/m²); it increases with clay content, soil compaction, depth, speed (roughly with the square of speed) and with moisture below the optimum.
• Q: How do you calibrate a seed drill? A: Jack up the drive wheel, work out the revolutions equal to a known fraction of a hectare, turn it at operating speed, weigh the seed from each spout, convert to kg/ha and adjust the metering lever until the target rate and even spout delivery are reached.
• Q: Which furrow opener suits zero tillage and why? A: An inverted-T or double-disc opener - it slices a narrow slot with minimum soil disturbance and handles loose residue without pushing it into the furrow.
• Q: What does a Happy Seeder do that a plain zero-till drill cannot? A: Its flail-type straw management unit cuts and lifts loose paddy straw ahead of the openers and drops it back as mulch, so wheat can be sown directly into heavy stubble instead of burning it.
• Q: Which two thresher settings control grain damage and unthreshed loss? A: Cylinder peripheral speed and cylinder-concave clearance; too high a speed or too close a clearance breaks grain, too low or too wide leaves unthreshed heads.
• Q: Why do paddy threshers run slower than wheat threshers? A: Paddy grain is easier to detach but far more prone to cracking and dehusking, so peripheral speed is kept near 12-16 m/s against about 20-25 m/s for wheat.
• Q: Field efficiency is 75% - what is lost in the other 25%? A: Turning at headlands, overlap, filling seed or fertiliser, unloading grain, clearing blockages, adjustments and minor breakdowns within the field.
• Q: Why is a rotavator not recommended as the only tillage tool every season? A: Repeated shallow rotary action destroys soil aggregates, creates a compacted layer just below the tilled depth and consumes the most power per metre of width; it should be alternated with deeper, non-inverting tillage.
• Q: Difference between position control and draft control on a tractor's hydraulics? A: Position control holds the implement at a set height irrespective of soil resistance; draft control raises or lowers it to keep the pull on the links constant, giving uniform loading in variable soil.

Common mistakes

• Dividing by 10 the wrong way in field capacity - TFC (ha/h) = W(m) × S(km/h)/10; mixing m/s with km/h gives answers 3.6 times out.
• Using the implement's overall frame width instead of the effective working width (row spacing × number of rows, less overlap).
• Forgetting to multiply the furrow cross-section by the number of bottoms when computing draft of a multi-bottom plough.
• Confusing theoretical with effective field capacity, or quoting field efficiency above 100%.
• Treating seed rate as independent of germination and field establishment when converting plant population to kg/ha.
• Calling a seed drill a planter - a drill controls the rate along the row, a planter controls the spacing of individual seeds.
• Reporting threshing efficiency when the question asks for cleaning efficiency or total loss, and ignoring broken-grain percentage.
• Quoting withdrawn IS numbers or assuming any implement qualifies for subsidy without a valid FMTTI test report.

Related topics

Farm tractors · Farm power and renewable energy · Soil mechanics and soil-tool interaction · Post-harvest processing and storage machinery · Precision agriculture and farm mechanisation policy · Irrigation and drainage engineering