Crop production involves operations like seedbed preparation, seeding, fertilizing, spraying, dusting, irrigation, harvesting, and threshing. Agricultural machines enhance land and labor productivity by ensuring timely operations and increasing output per unit time.
Besides their significant contribution to multiple cropping and agricultural diversification, this article discusses machinery used for these operations.
Tillage is the mechanical manipulation of soil to create favorable conditions for crop growth, breaking compacted surfaces to a certain depth and loosening soil for root penetration and spread.
Tillage is the most labor-intensive and challenging field operation. It is classified as primary or secondary. Primary tillage involves initial soil breakup, while secondary tillage breaks clods and prepares seedbeds for planting.
Primary tillage implements include ploughs, while secondary tillage uses harrows and cultivators.
Primary tillage is not always necessary before secondary tillage if soil conditions, such as non-dry or non-hard ground, permit.
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Primary Tillage Operations in Agriculture
Primary tillage constitutes the initial major soil-working operation, designed to reduce soil strength, cover plant materials, and rearrange aggregates. Operations to open cultivated land for seedbed preparation are known as primary tillage.
Implements include hand-operated tools, tractor-drawn, or animal-drawn equipment, such as moldboard ploughs for animals and moldboard, disc, chisel, subsoiler, or other ploughs for tractors.
Plough Types for Primary Tillage
The primary tillage implement is the plough, used for cutting, breaking, and inverting soil partially or completely. Different plough types suit varying soil characteristics:
- Moldboard plough
- Disc plough
- Chisel plough
- Subsoiler
- Rotary plough
1. Moldboard Plough for Soil Inversion:
This ancient tillage tool inverts soil to bury crop residue, consisting of:
- Share
- Mouldboard
- Landside
- Frog
- Standard
- Beam
- Handle
Parts a) to e) form the plough bottom. Moldboard ploughs may have one or multiple bottoms, depending on available power. Size is denoted by bottom number and furrow width (e.g., a 3 x 15 cm plough cuts three 15 cm furrows, totaling 45 cm).
The share cuts the furrow slice, lifted and inverted by the moldboard’s curvature. The landside ensures a neat furrow, absorbing sideways thrust, with a detachable heel.
The frog joins share, moldboard, and landside. The standard connects to the beam, sometimes cast as one with frog and landside. The beam links to the power source, and handles guide animal-drawn ploughs.
2. Disc Plough for Hard Soils:
The disc plough uses discs of specific diameter and curvature mounted on a frame, suitable for hard, dry, or sticky soils where moldboard ploughs fail.
Multiple discs depend on available power. Disc ploughs penetrate by weight, not suction, requiring heavier construction and sometimes additional weights.
3. Disc and Tilt Angles in Plough Design:
Discs are tilted relative to vertical (tilt angle, 15–25°) and travel direction (disc angle, 42–45°). Disc angle affects cut width, requiring more pull if excessive, while tilt angle influences penetration, maximized near vertical. Disc ploughs, less effective at inversion, suit hot climates with hard-baked land.
4. Additional Attachments for Ploughs:
- i. Moldboard Plough:
- Coulters (disc or knife-edge) enhance efficiency, aligned behind the share’s point.
- Jointers, miniature moldboard-shaped parts, detach soil slices to aid penetration and inversion.
- ii. Disc Plough:
- Scrapers cover trash and prevent soil buildup on discs in sticky soils.
5. Chisel Plough for Deep Soil Work:
Chisel ploughs use deep tines to break subsoil, aiding drainage and removing deep-rooted weeds. Their sturdy construction requires significant power for deep operation.
6. Subsoiler for Soil Pan Breakage:
Subsoilers break hard soil pans from continuous ploughing, improving drainage and aeration. High-powered crawler tractors are typically required.
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Secondary Tillage Implements in Agriculture
Secondary tillage implements, used before or after planting, prepare seedbeds, mix fertilizer, break soil crusts, or clods from primary tillage, and perform weeding or earthing-up post-planting. Examples include harrows, cultivators, rotary cultivators, and rollers, either mounted or trailed.
1. Harrow Types for Soil Preparation:
Harrows cut soil shallowly to smooth, pulverize, cut weeds, and mix materials. They break clods post-ploughing, collect trash, and level seedbeds. Types include:
- i. Disc Harrow: Discs, like those in disc ploughs, are mounted on axles forming gangs. Gang angles, adjustable relative to travel direction, increase soil pulverization with larger angles.
- ii. Spike-Tooth Harrow: Pegs or spikes on a bar, mounted on a frame, with adjustable angles, break soil and collect weeds.
- iii. Chain Harrow: A flexible chain-link mat, pulled by a tractor, aids weed collection and manure mixing.
2. Rotary Hoe for Soil Pulverization:
Rotary hoes use revolving shovels to break and pulverize soil via impact, controlled by tractor speed. Shovels, powered by the tractor’s PTO through a gearbox and sprocket-chain, have limited use in dry, arid conditions due to poor penetration, high wear, and dust generation.
3. Cultivators for Weed Control and Soil Work:
Cultivators feature soil-working tines or shares on robust frames, classified as:
i. Rigid-Tine Cultivator: Strong tines with cutting shovels or sweeps, arranged in rows, with adjustable spacing for weed hoeing. Reversible points extend use. Depth adjusts via shovel position, pitch (via top link), land wheel, or tractor hydraulics.
ii. Spring-Tine Cultivator: Spring steel tines withstand obstructions, preferred for rocky soils, breaking clods at shallower depths than rigid types.
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