ABET 121: Farm Machinery and Tillage

• Basic farm machineries and mechanization are covered in ABET 121.
• The lecture will cover tillage machinery, primary tillage operations, secondary tillage operations, and general-purpose tillage operations.

Intended Learning Outcomes:

• Students will identify machinery used in land preparation in both upland and lowland farming.
• Students will understand basic and proper land preparation machinery maintenance.

Tillage:

• Tillage is the mechanical manipulation of soil for any purpose, but usually for nurturing crops.
• Tillage involves land preparation for growing crops.

Tillage Objectives:

• Develop a desirable soil structure for seedbed or rootbed.
• Control weeds or remove unwanted crop plants.
• Manage plant residues.
• Minimize soil erosion through practices like contour tillage, listing, and proper placement of plant residues.
• Establish specific surface configurations for planting, irrigating, drainage, or harvesting.
• Incorporate and mix fertilizer, manure, pesticide, or soil amendments into the soil.
• Accomplish segregation by moving soil, removing rocks, or harvesting roots.

Methods and Equipment:

• A tillage tool is an individual soil engaging element, such as a plow bottom or disk blade.
• A tillage implement consists of a single tool or a group of tools, together with the associated frame, wheels, hitch, control and protection devices, and any power transmission components.

Tillage Implement Selection:

• The set of implements chosen depends on local customs, crop type, soil moisture level, soil type, and the amount of plant residue from the previous crop.
• Implement selection is also affected by the availability of implements, power units, labor, and capital.

Soil plowing:

• Soil plowing involves a few important terms frequently used in connection with it
• Terms include furrow, wall, furrow crown, back furrow, dead furrow, furrow depth, furrow slice, plow sole, ridge height

Terms:

• Back Furrow: A raised ridge left at the center of a strip of land when plowing is started center to side.
• Dead Furrow: An open trench left between adjacent strips of land after finishing the plowing operation.
• Furrow: A trench left when the plow bottom cuts and turns the furrow slice.
• Furrow Crown: A peak of the turned furrow slice.
• Furrow Depth: A ditch depth, pat depth, trench depth, or depth of depression below a specified soil surface.
• Furrow Slice: A soil mass cut, lifted, pulverized, inverted, and thrown to one side of the plow bottom.
• Headland: Unplowed soil at the end of the furrow strip.
• Ridge Height: Bed height, hill height, windrow height, or height of the soil above a specified soil surface.
• Land: Unplowed soil.

Primary Tillage:

• Primary tillage is the first soil tillage after the last harvest.
• It's normally conducted when the soil is wet enough to allow plowing and strong enough to give reasonable levels of traction.
• It can be done immediately after crop harvest or at the beginning of the next crop season.

Implements used for Primary Tillage:

• Moldboard Plow
• Disk plow and tillers
• Chisel plow
• Subsoilers
• Stubble-mulch plow tillers
• Listers and bedders

Moldboard Plow:

• Moldboard plows are the most common implements used for primary tillage, but they are never used in secondary tillage.
• A moldboard plow cuts soil, lifts it, and turns it at least partly upside down using a curved plate, or moldboard.

Main components of a Moldboard Plow:

• Share: The part of the plow bottom that penetrates the soil and makes a horizontal cut below.
• Moldboard: The curved part which lifts, turns, and pulverizes the soil slice on the surface.
• Land Side: The flat plate which presses against the furrow wall and prevents the plow from lateral swinging.
• Frog: It is the part to which share, landside, and moldboard are attached.

Disk Plow:

• Disk plows implement individually mounted concave disk blades which cut, partially or completely invert soil slices to bury surface material and pulverize the soil.
• Disk diameters are commonly between 60-70 cm.
• The disk angle (side angle) varies from 42°-45°.
• The tilt angle varies from 15°-25°.

Main components of Disc Plow:

• Concave Disc: A circular concave steel plate used for cutting and inverting the soil.
• Frame: The structure on which the standards are fitted.
• Hitch: The portion of an implement designed to connect the implement to a power source.
• Standard: Upright support that connects the shank to tillage implement frame.
• Scraper: A component that scrapes the soil adhering to the concave side of the disc.

Classification of Disc Plow:

• One-way Disc Plow
• Tractor-mounted or Integral Disc Plows are attached to the tractor by three-point hitch linkages and are fully carried by the tractor during transport.
• Semi-mounted or Semi-integral Disc Plow: Disc plow is attached to the tractor's lower hitch points and is raised/lowered by the tractor hitch as well as a remote hydraulic cylinder on the rear transport wheel.
• Reversible Disc Plow.

Chisel Plow:

• An implement designed for primary tillage at depths from 15-46cm.
• It shatters, mixes, and aerates the soil with little soil inversion and little coverage of plant residue.
• It is most effective when the soil is dry and firm because the tools can pass through wet soil with almost no shattering action.

Subsoilers:

• Used to break through and shatter compacted or otherwise impermeable soil layers to improve rainfall penetration.
• Has heavy standards that can be operated at depths of 45-75cm or more.
• Most effective under dry and firm soil.
• Subsoiling operation is usually followed by another primary tillage before secondary tillage begins.

Stubble-mulch Plow:

• Stubble-mulch plows are made of wide V-shape sweeps that operate at shallow depths of 10cm or less.
• The purpose is to cut weed roots just below the surface and leave the stubbles of the previously harvested crops on the surface to act as mulch (cover) to retain moisture and reduce soil erosion.

Stubble-mulch Tiller:

• It is a combination of chisel plow and disk harrows.
• It is used where it is essential to till deep to break the old plow pan.

Listers and Bedders:

• Lister: Used to create furrows for planting, resembling a double moldboard plow; planters are often attached to listers to accomplish planting in the same operation.
• Bedders: Used to make ridges or beds when it is desirable to plant on the bed in areas of high rainfall; bedders are made of disk implements that work in pairs to form ridges.

Secondary Tillage:

• Secondary tillage includes any tillage operations performed after the primary tillage.
• The main objective of secondary tillage is to break down large clods and prepare an ideal seedbed for planting.
• Equipment most commonly used in secondary tillage are harrows and cultivators.

Disk Harrows:

• Differ from disk plows in that there is no tilt angle, and several blades are mounted on a common axis called a "gang."
• The gang may be arranged in different configurations, such as single action, offset, or tandem.
• Disk harrows may be mounted or pull type.
• Disking with larger disks should be followed by lighter disks for final seedbed preparation.
• Disk weight ranges from 20-200kg/disk.
• Disk diameter ranges from 40-80cm.

Disk Harrow Spacing:

• 18cm when the ground is not hard with little surface residue.
• 23cm when mixing chemicals or cutting of surface trash is desirable.
• 28cm for harder soil or when a heavy surface residue is present.
• Spike Tooth Harrow: It is a harrow with peg-shaped teeth of diamond cross-section to a rectangular frame.
• Spike tooth harrows may be of rigid type and flexible type.
• It is used to break the clod, stir the soil, uproot the weeds, level the ground, break the soil, and cover the seeds.
• Its principle is to smoothen and level the soil directly after plowing.

Spring Tooth Harrow:

• A harrow with tough, flexible teeth, suitable for working in hard and stony soils.
• It gives a spring action in working condition.
• Used in the soil when obstructions like stones, roots, and weeds are hidden below the ground surface.
• This type pulverizes the soil and helps in killing weeds.
• Spring tooth harrows are fitted with springs having loops of elliptical shape.

General-purpose Tillage:

• Performs functions simultaneously that of initial cutting, breaking, and pulverizing the soil.
• Combines primary and secondary tillage in one operation.
• Implements used in general-purpose tillage are rotavators and floating power tillers.

Rotavators:

• Constructed with a set of cutting knives or tines mounted on a horizontal power-driven shaft rotating at high speed.
• The knives slice thin sections of the soil and pulverize them by centrifugal force.
• Rotavators are suited for both dry and wet land operations.
• Rotavators are mounted on 2-wheel or 4-wheel tractors and driven by the tractor PTO.

Floating Power Tillers:

• Specially designed power tillers for wet land operation fitted with front-mounted cutting blades on a cagewheel.

Summary:

• Tillage is a mechanical manipulation of soil for any purpose, but usually for nurturing crops.
• The three classifications of tillage operation are primary tillage operation, secondary tillage operation, and general-purpose tillage operation.