Establishing a nursery for oil crops is a foundational step in successful oil crop production, particularly in Kenya's diverse horticultural sector. Nurseries provide a controlled environment for raising healthy seedlings that can later be transplanted to the field, ensuring higher survival rates and uniform crop establishment. Selecting an appropriate site for the nursery is critical because it affects seedling development, pest and disease incidence, and operational efficiency. This chapter focuses on the strategic considerations for nursery site selection, the definition and characteristics of oil crops, and the tools and equipment necessary for nursery establishment.

1.1 Nursery site selection

Nursery site selection is a strategic activity that determines the success of oil crop production from seedling stage to field establishment. In Kenya, where climatic and soil conditions vary widely, choosing the right nursery site can mitigate risks such as water scarcity, pest outbreaks, and poor seedling growth. A well-chosen site enhances resource use efficiency, reduces operational costs, and facilitates management practices such as irrigation, shading, and pest control.

1.1.1 Definition of oil crops

Understanding what qualifies as oil crops is essential for nursery establishment, as these crops have specific growth requirements and economic value. Oil crops are plants cultivated primarily for the extraction of vegetable oils used in food, industrial applications, and biofuels. In Kenya, oil crops contribute significantly to the horticultural economy through products such as cooking oils, cosmetics, and animal feed. Examples include sunflower, groundnut, sesame, soya bean, oil palm and coconut. Perennial oil crops such as oil palm and coconut are normally raised as seedlings in a nursery before transplanting, so the choice of nursery site matters for them from the start.

Characteristics of oil crops

• High oil content seeds: Oil crops produce seeds, nuts or fruits rich in oils, such as sunflower, groundnut, and sesame, which are processed to extract vegetable oils.
• Adaptability to various climates: Different oil crops suit different climatic zones. Sunflower and sesame do well in drier, semi-arid areas, while crops such as oil palm and coconut need warm, humid lowlands.
• Economic importance: These crops provide income for smallholder farmers and supply the agro-processing industry, which creates jobs in milling, refining and marketing.
• Nutritional value: Oils from these crops are essential sources of fats and vitamins in the diet, supporting food security.
• Crop rotation benefits: Oil crops often improve soil fertility and break pest cycles when rotated with cereals or legumes on farms. Legumes such as groundnut and soya bean also fix nitrogen.

1.1.2 Importance of nursery site selection

The choice of nursery site directly influences seedling quality, operational efficiency, and ultimately the yield of oil crops. Selecting a suitable site reduces seedling mortality and promotes vigorous growth, which is critical for supplying farmers with healthy planting material on time. For example, a nursery set in a low, waterlogged hollow will lose seedlings to damping-off and root rot, while one on a gently sloping, well-drained site with water nearby will raise uniform seedlings with far fewer losses.

Benefits of choosing the right site

• Better seedling quality: Seedlings raised under suitable conditions grow sturdy stems and healthy roots, and establish quickly after transplanting.
• Lower seedling mortality: A suitable site avoids stresses such as waterlogging, drought and wind damage, so fewer seedlings are lost and fewer have to be replaced.
• Reduced operating costs: Less money is spent on corrective work such as drainage repairs, extra shading, long-distance water carrying or repeated pest control.
• Easier management: Routine tasks such as watering, weeding, inspection and spraying are quicker and need less labour when the site is well laid out.
• Timely supply of planting material: Seedlings reach transplanting size on schedule, so they can be delivered to the field when the rains begin.
• Protection of the investment: A well-chosen site protects permanent structures such as shade frames, water tanks and fencing from damage by flooding, erosion or theft.

1.1.3 Factors considered when siting a nursery

Choosing a nursery site involves evaluating multiple environmental, logistical, and economic factors to optimise seedling production. Each factor is checked on the ground before any clearing begins, ideally by walking the site, digging a test pit and noting the position of water, roads and neighbouring crops. These criteria ensure that the nursery supports healthy growth stages and offers ease of management, which is crucial for commercial and small-scale oil crop producers.

Environmental factors

• Sunlight and temperature: Nurseries require adequate sunlight, typically 6-8 hours daily, to promote photosynthesis, with moderate temperatures that do not stress seedlings. In hot, high-radiation areas shading may be needed.
• Soil type and drainage: Soils should be fertile and well drained to prevent waterlogging, which causes root rot and damping-off. Sandy loam soils are preferred for most oil crops.
• Topography: Flat or gently sloping land minimises erosion and facilitates irrigation. Steep slopes increase runoff and complicate management, while hollows collect water and cold air.
• Wind protection: Sites sheltered from strong winds reduce physical damage to seedlings and moisture loss. Planting windbreaks can be beneficial.
• Pest and disease pressure: Sites should be away from mature oil crop fields, rubbish heaps and known pest or disease hotspots. This limits seedling exposure and reduces the cost of chemical control.

Logistical factors

• Water source proximity: Close access to a reliable source of clean water such as a borehole, river or piped supply enables efficient irrigation. Water that is salty or polluted harms seedlings.
• Accessibility: The nursery should be near transport routes to ease movement of seedlings, inputs, and labour, which reduces transport costs and damage to seedlings in transit.
• Security: Locations with low risk of theft or vandalism protect nursery investments. This is a common concern for urban and peri-urban nurseries, where fencing may be needed.

Economic factors

• Land cost and tenure: Affordable land with secure tenure encourages investment in permanent nursery infrastructure.
• Labour availability: Proximity to communities with skilled labour reduces operational costs and improves nursery management.
• Market access: Being near buyers such as commercial farms or agro-dealers facilitates timely seedling sales, enhancing profitability.

1.1.4 Tools, equipment and materials used

A variety of tools and materials are essential to establish and maintain a nursery for oil crops efficiently. Proper equipment ensures quality seedling production, reduces labour intensity, and supports good agricultural practice. Hand tools for clearing the site and working the soil, such as the panga, jembe, slasher and rake, are used first, followed by containers, watering and shading equipment once the nursery is set up.

Usage and maintenance of other nursery tools

• Seedling trays: Use clean trays to prevent disease spread. Wash and disinfect trays after each nursery cycle.
• Watering can: Water seedlings gently to avoid dislodging soil. Clean the nozzle regularly to prevent clogging.
• Shading net: Install securely to prevent damage from wind. Replace nets every 2-3 years or when torn.
• Nursery beds: Construct with good drainage and organic matter-rich soil. Remove weeds frequently to reduce competition.
• Pruning shears: Sterilise after use to prevent disease transmission. Keep blades sharp for clean cuts.
• Soil testing kit: Calibrate periodically and follow the manufacturer's instructions for accurate results.

1.1.4.1 Panga

The panga is a heavy, broad-bladed steel knife with a wooden or plastic handle. It is the main cutting tool when a nursery site is first cleared, because it can cut through woody shrubs, saplings and thick grass that a slasher cannot handle. For example, before marking out a nursery for oil palm seedlings, a worker uses a panga to cut bushes and low branches on the chosen plot.

Uses in nursery establishment:

• Clearing bush: Cuts shrubs and small trees from the site so that sunlight and air reach the seedlings.
• Cutting stakes and poles: Prepares pegs for marking out the site and poles for the shade frame and fence.
• Trimming branches: Removes overhanging branches that would shade the nursery too heavily or drop debris.
• Cutting windbreak and fencing material: Shapes live fence cuttings and brushwood for protecting the nursery.
• Chopping cleared material: Cuts bush and weeds into short pieces for easy collection and composting.

Care and safe use:

• Sharpening: Keep the blade sharp with a file, since a blunt panga needs more force and slips more easily.
• Safe handling: Cut away from the body, keep other workers at a safe distance, and wear boots and gloves.
• Handle checks: Make sure the handle is firmly fixed to the blade before each use.
• Cleaning: Wipe off soil and sap after use to prevent rust.
• Storage: Keep in a sheath or on a rack in a dry store, out of reach of children.

1.1.4.2 Jembe

The jembe is the common Kenyan hand hoe, with a flat steel blade fixed to a long wooden handle. It is used to cut, dig, turn and move soil and to uproot weeds, which makes it useful at every stage of setting up a nursery. For example, a worker uses the jembe to dig a test pit on the proposed site to check soil depth, texture and drainage before the site is accepted.

Uses in site establishment:

• Digging test pits: Opens the soil to inspect depth, colour, texture and the level of any waterlogging.
• Uprooting weeds and stumps: Removes perennial weeds such as couch grass with their roots and small stumps left after bush clearing.
• Digging drainage channels: Makes shallow ditches that lead excess water away from the nursery.
• Digging post holes: Opens holes for fence and shade-frame posts.
• Weed control: Cuts weeds around the nursery and along paths to reduce competition and hiding places for pests.

Care and safe use:

• Sharpening: Sharpen blades regularly for efficient soil work.
• Handle fit: Check that the blade is tightly fixed and the handle is not cracked.
• Posture: Keep a firm stance and swing the jembe at a controlled pace to avoid back strain and injury to the feet.
• Cleaning: Scrape off soil after use, as wet soil causes rust.
• Storage: Store in a dry place to avoid rust.

1.1.4.3 Slashers

A slasher is a long-handled cutting tool with a curved or straight steel blade, swung in a low arc to cut grass and soft weeds. It covers large areas faster than a jembe or panga when the vegetation is not woody. For example, on a site covered in tall grass, a slasher is used to cut the grass to ground level so that the plot can be inspected and pegged out.

Uses in nursery establishment:

• Clearing tall grass: Cuts grass and herbaceous weeds on the site before clearing and marking out.
• Slashing the perimeter: Keeps a cleared strip around the nursery that removes hiding places for rodents and snakes.
• Cutting weeds along drains and paths: Keeps water channels open and walkways clear.
• Reducing pest habitat: Removes tall vegetation that harbours insects and diseases near seedlings.
• Maintaining the surroundings: Regular slashing after establishment keeps the area tidy and reduces fire risk in dry weather.

Care and safe use:

• Safe distance: Keep other workers well out of the swing arc.
• Protective clothing: Wear boots, long trousers and eye protection, since stones and plant pieces can fly up.
• Sharpening: Sharpen the blade with a file or whetstone to give clean cuts.
• Handle checks: Ensure the blade is securely fixed to the handle.
• Storage: Clean, lightly oil the blade, and hang the slasher in a dry store.

1.1.4.4 Rake

The rake is a hand tool with a row of steel teeth (tines) fixed to a head on a long handle. It is used to gather loose material and to smooth the soil surface, so it comes after the cutting tools in site clearing. For example, once grass and bush have been cut, the rake is used to collect the cut material, stones and roots into heaps for removal.

Uses in nursery establishment:

• Collecting cleared vegetation: Gathers cut grass, twigs and weeds into heaps for composting or disposal.
• Removing stones and roots: Pulls out stones, roots and other debris that could obstruct seedling growth.
• Breaking small clods: Breaks up small soil lumps when the soil is dry enough.
• Levelling the surface: Spreads and evens out loose soil so that water does not collect in low spots.
• Keeping the nursery clean: Clears fallen leaves and debris from paths and work areas to reduce places where pests can hide.

Care and safe use:

• Tine checks: Check that the tines are not bent or broken and that the head is firmly fixed.
• Safe placement: Never leave a rake lying with the tines pointing up, as it can cause injury.
• Cleaning: Remove soil and plant material from the tines after use.
• Rust prevention: Dry the head and lightly oil the tines before storage.
• Storage: Hang the rake on a wall or rack with the tines facing the wall.

Chapter Summary

This chapter covered the essential steps involved in establishing an oil crops nursery, beginning with the selection of an appropriate site. It defined oil crops and highlighted the importance of choosing a suitable nursery location by considering factors such as soil quality, water availability, and protection from harsh weather. The chapter also described the key tools and equipment used in nursery preparation, including the panga, jembe, slashers, and rake. Preparation of the nursery bed was discussed in detail, followed by the correct methods for planting seeds to ensure healthy seedling growth. Nursery management practices were thoroughly examined, focusing on mulching, shading, hardening off, watering, fertilizer application, pest and disease control, and pricking out to maintain optimal growing conditions. Practical aspects of carrying out nursery bed preparation, planting, and ongoing nursery bed management were also emphasized to equip learners with hands-on skills for successful oil crop production.