Harvesting is a critical phase in horticultural production that directly affects crop quality, yield, and profitability. Efficient use of harvesting machinery enhances productivity by reducing labor intensity and minimizing crop damage during collection. In Kenya, where horticulture contributes significantly to both domestic food supply and export earnings, mastering operation of harvesting machinery is essential for farm managers and workers to optimize harvest timing and handling.

5.1 Harvesting machinery

Harvesting machinery refers to equipment designed specifically to facilitate the collection of horticultural crops from the field or orchard. These machines vary according to crop type, terrain, and scale of production. Understanding the different types and their capabilities allows horticulture professionals to select suitable machinery that aligns with farm conditions and crop characteristics.

5.1.1 Types of harvesting machinery

Harvesting machinery can be broadly categorised based on its mode of operation, crop specificity, and mechanisation level. Each type offers unique advantages and limitations depending on the horticultural context. Powered mechanical harvesters increase speed and reduce labour costs, but they require capital investment and trained operators. Example: a farm growing potatoes, French beans and forage for its dairy cows may need a potato harvester, a combine, a mower and a baler, each doing a different job at a different time of year.

Manual harvesting aids

These include hand-held tools and simple mechanical devices that assist workers in picking or cutting crops. Examples are sickles, pruning shears, and handheld fruit pickers. They are affordable, require minimal maintenance, and are suitable for small-scale farms or crops that need delicate handling, such as flowers or soft fruits.

Semi-mechanised harvesters

These combine manual labour with mechanical assistance, such as motorised platforms with conveyor belts that workers use to pick fruit. They are used in some large tree fruit orchards where delicate handling is necessary but some mechanisation boosts efficiency.

Specialised harvesting machines

Certain horticultural crops require highly specialised machines due to their growth form or harvesting method. Examples include:

• Vegetable harvesters: Machines such as bean pickers and cabbage harvesters cut or strip the produce from the plant.
• Grape harvesters: Have shaking and collection systems that remove the berries from the vines.
• Fruit harvesters: Machines such as apple or citrus harvesters that shake or pick fruit mechanically.
• Flower harvesting platforms: Enable workers to cut flowers at height.

These machines are designed to optimise harvest quality while minimising damage and are often used on commercial farms with large acreage.

Comparison of the main harvesting machines

5.1.1.1 Balers

A baler is a machine, usually pulled and powered by a tractor, that picks up cut hay, straw or other forage from the field, compresses it and ties it into compact bales. Bales are easier to load, transport and store than loose material. Example: on a mixed horticultural farm, a round baler can gather dry straw after a cereal harvest, and the bales are then used as mulch between strawberry rows or as bedding for livestock.

The main types of balers are:

• Small rectangular balers: Produce small square bales that one or two workers can lift by hand. They suit small farms and sales of hay or straw in small lots.
• Large rectangular balers: Produce big, dense square bales that need a loader to handle. They suit large farms and long-distance transport because the bales stack tightly.
• Round balers with a fixed chamber: Roll the crop in a chamber of constant size, giving a bale with a firm outer layer and a softer core. They are suited to dry hay and straw.
• Round balers with a variable chamber: Roll the bale while the chamber grows, so the bale is firm from the core to the outside. They handle a wider range of crop conditions.
• Self-propelled balers: Carry their own engine and do not need a separate tractor. They are used on large commercial farms.

The main parts of a baler are:

• Pick-up reel: Tines lift the crop from the windrow (the row of cut material) and feed it into the machine.
• Feeder or rotor: Moves the crop from the pick-up into the baling chamber in a steady flow.
• Baling chamber: Compresses the crop into a bale of the required shape and density.
• Tying or wrapping mechanism: Binds the finished bale with twine, wire or net wrap so that it keeps its shape.
• Power take-off (PTO) shaft and drawbar: Connect the baler to the tractor, which supplies power and pulls the machine.
• Bale ejector or discharge gate: Releases the finished bale onto the ground or onto a bale carrier.

5.1.1.2 Mowers

A mower cuts standing grass, forage or cover crops close to the ground using blades or a cutter bar. In horticulture it is used to cut forage for hay, to manage grass between orchard rows and to cut cover crops before they are ploughed in. Example: in a citrus orchard, a tractor-mounted rotary mower keeps the grass between tree rows short so that it does not compete with the trees for water.

The main types of mowers are:

• Sickle bar mowers: A long cutter bar with a blade that moves rapidly from side to side against fixed guards. They give a clean cut and suit forage meant for hay.
• Rotary mowers (disc and drum): Blades spin horizontally at high speed and cut the crop by impact. They work faster than sickle bars and cope well with thick grass.
• Flail mowers: Many small hinged blades on a rotating shaft chop and shred the crop. They are used for rough grass, orchard alleys and crop residues.
• Pedestrian (walk-behind) mowers: Small engine-powered machines guided by hand. They suit small plots, nursery paths and compounds.
• Mounted and trailed mowers: Mounted types attach to the tractor's three-point linkage and are lifted for transport. Trailed types are pulled behind the tractor and carried on their own wheels.

The main parts of a mower are:

• Cutter bar or cutting deck: Carries the blades and sets the width of the cut.
• Blades or knives: Do the cutting and must be kept sharp and balanced.
• Gearbox and drive: Transfer power from the tractor PTO or the engine to the blades.
• Skid shoes or height-adjustment system: Control the cutting height and protect the cutter from the soil.
• Guards and shields: Cover the moving parts and stop stones and debris from being thrown out.
• Hitch or linkage: Connect the mower to the tractor.

5.1.1.3 Combined harvesters

A combined harvester, or combine, performs several harvest operations in a single pass: cutting the crop, threshing it, separating the grain or seed from the straw and cleaning it. It is used mainly for cereals and also for some horticultural seed crops such as beans and peas grown for dry seed. Example: a farmer growing dry beans for seed can use a combine fitted with a suitable header to harvest and clean the crop in one pass, instead of cutting, drying and threshing separately.

The main types of combined harvesters are:

• Self-propelled combines: Have their own engine, cab and drive wheels. They are used on large farms where speed and capacity are important.
• Tractor-drawn or tractor-mounted combines: Are powered through the tractor and cost less. They suit medium farms that already own a suitable tractor.
• Conventional combines: Use a threshing drum and straw walkers to separate the grain from the straw.
• Axial-flow (rotary) combines: Pass the crop along a rotor, where threshing and separation take place together. They handle a wide range of crops.

The main parts of a combined harvester are:

• Header (cutting platform): Cuts the crop and gathers it towards the centre of the machine.
• Reel: Pushes the standing crop onto the cutter bar and onto the platform.
• Feeder house: A conveyor that carries the cut crop from the header into the threshing unit.
• Threshing drum or rotor and concave: Rub and beat the crop to detach the grain or seed from the heads or pods.
• Separation unit: Straw walkers or a rotor carry the straw out while the grain falls through.
• Cleaning shoe: Sieves and a fan blow away chaff and light material so that clean grain remains.
• Grain tank and unloading auger: Store the cleaned grain and discharge it into a trailer.

5.1.1.4 Potato harvester

A potato harvester digs potato tubers from the ridges, lifts them and separates them from soil, stones and haulms (the stems and leaves). Using a machine for this work is faster than hand digging and reduces the labour required at harvest. Example: on a potato farm with several hectares to lift, a tractor-drawn single-row harvester digs the tubers while workers on the machine remove stones and damaged tubers before the potatoes are bagged.

The main types of potato harvesters are:

• Spinner (rotary) diggers: A share lifts the ridge and rotating arms throw the tubers onto the surface, where workers collect them by hand. They are simple and suit small to medium farms.
• Elevator diggers: A share lifts the soil and tubers onto a moving chain or web that shakes the soil away. The tubers are laid on the surface or carried further.
• Single-row complete harvesters: Dig, clean and load tubers into a bin or trailer. They are tractor drawn and suit medium farms.
• Multi-row harvesters: Harvest two or more rows in one pass. They are used on large commercial farms.
• Other root crop harvesters: Similar machines lift root crops such as carrots and onions from the soil.

The main parts of a potato harvester are:

• Digging share or blade: Cuts under the ridge and lifts the soil with the tubers.
• Web or elevator chain: A moving chain of bars that carries the soil and tubers backwards while loose soil falls through.
• Agitators or shakers: Shake the web so that the soil separates from the tubers.
• Haulm rollers or haulm remover: Separate the stems and leaves from the tubers.
• Sorting or picking table: Workers remove stones, clods and damaged tubers by hand.
• Depth wheels: Adjust and control the digging depth so that tubers are not cut.
• Elevator and bin or trailer: Carry the cleaned potatoes into a storage bin or a trailer.

5.1.1.5 Threshers

A thresher separates grain or seed from the stalks, heads or pods after the crop has been cut and dried. Threshing is done by beating, rubbing or rotating the crop against a fixed surface, and the grain is then cleaned of chaff. Example: after cutting and drying a bean crop, a farmer feeds the dry plants into a stationary multi-crop thresher driven by a tractor PTO, which delivers clean beans into bags.

The main types of threshers are:

• Hand-fed stationary threshers: The crop is fed into the machine by hand. They are suited to small and medium farms.
• Axial-flow threshers: The crop moves along the length of a rotating drum, which gives thorough threshing and good separation.
• Maize shellers: Remove kernels from the cob. They are available as hand-operated and engine-powered models.
• Multi-crop threshers: Can be adjusted for several crops, such as wheat, beans and sorghum, by changing the drum speed and concave clearance.
• Tractor PTO, engine or electric motor driven threshers: The power source depends on what is available on the farm.

The main parts of a thresher are:

• Feed hopper or feed tray: Guides the crop into the threshing unit.
• Threshing drum (cylinder): A rotating drum with pegs, bars or rasps that beats the grain from the crop.
• Concave: A curved grid, set close to the drum, against which the crop is rubbed. The clearance is adjusted to suit the crop.
• Sieves and cleaning fan: Separate the grain from chaff and blow light material out of the machine.
• Outlets: One discharges clean grain and another discharges straw or waste.
• Frame, wheels and drive pulley: Support the machine, make it movable and connect it to the power source.

Chapter Summary

This chapter provided a comprehensive overview of harvesting machinery, detailing various types including balers, mowers, combined harvesters, potato harvesters, and threshers. It explained the specific uses and operation methods for each type of machinery, emphasizing their roles in efficient farm harvesting processes. The chapter also covered essential maintenance practices such as servicing, repair, and proper storage to ensure longevity and optimal performance of harvesting equipment. Practical guidance was given on how to operate each category of harvesting machinery effectively on the farm. Additionally, the chapter revisited maintenance with a focus on routine care and troubleshooting to prevent breakdowns. Overall, it equipped learners with the knowledge to handle harvesting machinery competently, maintain it properly, and apply operational skills in real farm settings.