Agriculture Form 3 – Crop Production VI (Field Practices II)

Introduction

• There are many crops cultivated in Kenya.
• These crops are grown for various uses and require different ecological conditions.

Definitions:

• Hybrids – These are crop varieties developed by crossing two pure lines.
  • Composites – These are crop varieties developed through repeated mass selection.
• Cultivars – These are varieties of crops which are cultivated in a given area.

Maize

• Main growing areas: Trans-Nzoia, Nakuru, Uasin Gishu, Laikipia districts and others.
• Ecological Requirements
• Altitude: Up to 2000m above sea level.
• Temperature: About 25°C.
• Soils: Freely draining, fertile loam soils.
• Rainfall: 750-1250mm, critical at silking and pollination stage.
• Varieties
• High altitude areas: Hybrids 611, 613 and 614C.
• Medium altitude areas: 511, 512, 622 and 632.
• Marginal rainfall areas: Katumani composite and Makueni composite.
• Coast regions: Coast composite and Katumani composite.

Seedbed Preparation

• Ploughing should be deep and done during the dry season to eradicate weeds.
• Requires medium tilth.
• Plant spacing 75-90cm x 20-30cm.
• Planting done at the onset of the rains. This helps to reduce pest attack.
• Dry planting in areas with inadequate rainfall is necessary.

Field Maintenance:

• Apply phosphatic fertilizer during planting at a rate of 120kg/ha P₂O₅.
• Also apply nitrogenous fertilizers as top dress at the rate of 200kg of ASN or CAN.
• Control weeds by cultivation, use of appropriate herbicides, uprooting, slashing, and mulching.

Pest Control

• Maize Stalk Borer:
  • Nature of damage: Bores the leaves causing windowing effect, and bores the stems and cobs.
• Control: Destruction of previous year’s crop residue, closed season, and application of chemicals.
• Maize Weevils:
• It is a storage pest.
• Damage: Bores holes into the maize grains, eating the contents.
• Control: Proper hygiene and sanitation in the stores.
• Use of chemicals such as Actellic Super.

Disease Control:

• Rust
• Cause: Fungus.
• Symptoms: Red or brown pustules on the leaves.
• Control: Plant resistant varieties and practice crop rotation.
• Smuts
• Cause: Fungus.
• Symptoms: Black sooty mass of spores on maize heads or cobs (ears).
• Control: Crop rotation, growing resistant varieties, and destruction of affected plant parts.
• Maize Streak Virus
• Cause: Virus.
• Symptoms: Yellow longitudinal stripes parallel to the midrib.
• Control: Use certified seed, early planting, and rogueing.

Harvesting

• Harvest the crop 3-9 months after planting depending on variety.
• Maize stalks are cut and stacked in the field.
• Cobs are removed by hand.
• For large scale harvesting, combined harvesters are used.
• Yields about 3,000kg to 4,500kg/ha.

Bulrush Millet

Areas where grown:

• Lower areas of Kirinyaga,
• Embu,
• Meru,
• Parts of Machakos,
• Kerio Valley.

Ecological Requirements

• Altitude: Does well in areas below 1200m.
• Rainfall: 500-600mm per annum.
• Soils: Light sandy soils.
• Varieties: Serere 2A, 3A, 6A, 17, 16/9.

Seed Bed Preparations

• Ploughing of land during the dry season.
• Soil should be of fine tilth since the seeds are small.

Planting:

• Done at the onset of the rains.
• Planted by broadcasting and row planting at a spacing of 60cm x 15cm.

Field Maintenance:

• Weeding is done until tillering.
• Top-dressing is done by use of sulphate of ammonia.

Pest Control

Birds

• Nature of Damage: Eats the seeds at milky stage.
• Control: Bird scaring devices.

Disease Control

Ergot

• Cause: Fungus.
• Symptoms: Heads become sticky.
• Control: Use of certified seeds, crop rotation, and destruction of affected crops.

Downy Mildew

• Cause: Fungus.
• Symptoms: Long, whitish lines on the leaves.
• Control: Crop rotation and field hygiene.

Harvesting

• Done by cutting off the heads.
• Drying of the heads.
• Threshing and winnowing of the grains.
• Stored under well-ventilated dry conditions.
• Yields about 1000kg/ha with good management.

Finger Millet

• Areas where grown: Western Kenya and Uganda.

Ecological Requirements

• Altitude: 0-2400m above sea level.
• Rainfall: 900mm, drought resistant in the early stages.
• Soils: Free draining fertile soils.

Varieties:

• Serere varieties developed at Serere in Uganda.
• Ultra lupin.
• 5.18 oats.

Land Preparations

• The seedbed should be thoroughly prepared to a fine tilth due to the small size of the seeds.
• It also helps to control weeds.

Field Operations

Planting

• Finger millet should be planted as early as possible in the season.
• It is usually broadcasted by hand.
• If planted in rows, the furrows should be 30-33cm apart and the plants should be thinned to 5cm apart within the rows.

Fertilizer Application

• Sulphate of ammonia at the rate of 125kg/ha is recommended for topdressing finger millet.

Weed Control

• Clean seedbed preparation.
• Uprooting.

Pest Control:

• Birds are controlled through scaring.

Disease Control

Head blast:

• Cause: Fungus.
• Symptoms: Brown spots with grey centres on the leaves and stems below the inflorescence.
• Control: Use of resistant varieties.

Harvesting

• Individual heads are cut with knives.
• Heads are dried, threshed, and winnowed.
• Yields 1650kg/ha with good management.

Sorghum

• It is grown in Western, northern, Rift Valley, Eastern, and some parts of Central Province.

Ecological Requirements

• Altitude: 0-1500m above sea level.
• Rainfall: 420-630mm. It is drought resistant.
• Soils: Fairly fertile and well-drained soils.

Varieties

• Dobbs variety.
• Serena variety.

Field Operations

Planting

• Broadcasting the seeds on the firmly prepared seedbed.
• Intercropped with other crops especially maize and beans.
• Can be planted in pure stands at a spacing of 60cm x 15cm.

Fertilizer Application

• Responds well to farmyard manure (FYM).
• Inorganic fertilizers are not commonly used in growing sorghum.

Pest Control

• Bird pests: They are the most common sorghum pests.
• They include:
• Quelea,
• Aethiopica (Sudan Dioch),
• Weaver birds,
• Starling bird,
• Bishop’s bird.
• They are controlled through:
• Killing them using explosives,
• Poison spraying in their breeding places,
• Use of flame throwers.
• Sorghum shoot-fly controlled by early planting, closed season, and application of insecticides.
• Stem borer – control by use of insecticides and field hygiene.

Disease Control

Common sorghum diseases include:

• Leaf blight.
• Anthracnose.
• Sooty stripe.
• Loose smut.
• Head smut.

Smuts are controlled by seed dressing, while the other diseases are controlled by growing resistant varieties.

Harvesting

• Sorghum is ready for harvesting 3-4 months after planting.
• Heads are cut off using a sharp knife after which they are sun-dried, threshed, winnowed, and stored.
• Up to 3000kg/hectare can be obtained with good management.

Beans

• Grown in all provinces where maize is grown.

Ecological Requirements

• Altitude: 1000-2100 metres above sea level.
• Rainfall: Average of 625mm per annum.
• Soils: Well drained loamy soils rich in organic matter.

Varieties

Varieties for dry beans:

• Rose Coco,
• Mwezi Moja,
• Canadian Wonder,
• Wairimu,
• Haricot,
• Mwitemania.

Variety for canning: Mexican 142.

Varieties for French Beans:

• Primeur,
• Long Tom,
• Saza,
• Master Piece,
• Monel.

Seedbed Preparation

• Land should be prepared early.
• Primary and secondary cultivation done to control perennial weeds.

Seed Selection and Treatment

• Select wholesome seeds free from damage and wrinkles.
• Seeds are dressed against bean fly.
• Seeds should be inoculated with appropriate bacteria (non-dressed seeds).

Planting

• Planted at the onset of the rains.
• Spacing 30-45cm x 15cm.
• Apply phosphatic fertilizer during planting time.
• Plant 2-4 seeds per hole.

Field Maintenance

• Provide sticks for the climbing varieties.
• Control of weeds through shallow cultivation.
• Top-dress with nitrogenous fertilizer, for example CAN.

Pest Control

• Bean-Fly
• Nature of damage: Feeds on the stems causing swelling at the roots.
• This results in wilting and death.
• Control: Dressing of seeds, early planting, and spraying with insecticides.
• Bean Bruchid (Storage Pest)
• Nature of damage: Makes dark circular windows on the grains.
• Control: Clean stores, fumigation, and seed dressing.

Disease Control

• Bean Anthracnose
• Cause: Fungus.
• Symptoms: Brown or black lesions on the underside of the leaves, pods, and stems.
• Control: Growing resistant varieties, crop rotation, destruction of crop residues, and spraying with fungicides.

• Bean Rust
• Cause: Fungus.
• Symptoms: Red brown pustules on the leaves.
• Control: Planting resistant varieties and spraying copper fungicides.

Harvesting

• Done during the dry season for dry beans and when the pods are dry.
• Threshing and winnowing done.
• Sorting of rotten, off types, and damaged ones.
• Sold to National Cereals and Produce Board when dry.
• For French beans, pick the pods when soft and green.
• Market immediately to avoid shrivelling.

Rice Production

Areas where grown:

• Mwea Tabere Irrigation Scheme.
• Ahero Pilot Scheme in Kano plains.
• Bunyala in Busia.
• Bura in Tana River.

Land Preparation

• Plots of 0.4 hectare are made with bunds constructed around them.
• Plots are flooded for four days.
• Rotavators/jembes are used to work the flooded fields on the fifth day.
• The land is then levelled and allowed to drain.

Water Control

• During land preparation, water level should be about 7.5-10cm.
• During levelling, water level should be 5cm.
• Water is drained off completely for direct sowing.
• For transplanted rice, water level should be 5cm at transplanting.
• Water level should be maintained at 1/3 the height of the plant until maturity.
• Water should be allowed to flow slowly through the fields.
• Old water should be changed every 2-3 weeks if the flow of water is not possible.
• Water introduced should always be warm to ensure pollination.

Fertilizer Application

• S.A applied in the nursery.
• Rate of 25kg SA for every nursery unit of 18.5m x 18.5m.
• Phosphatic fertilizers broadcasted in the field.
• Rate of 120kg/ha DSP before planting.
• S.A applied in the field in two splits before and after transplanting at a rate of 250kg/ha.

Flooding in Rice

Flood water in rice production is important for the following reasons:

• It provides good conditions for growth such as high humidity.
• Kills soil organisms.
• Prevents denitrification.

Weed Control

• Controlled through flooding.
• Appropriate herbicides such as propanil and butachlor are also used.

Harvesting of Industrial Crops

• Cotton, pyrethrum, sugarcane, coffee, and tea.

Harvesting of Cotton

Stage of harvesting

• Takes 4 months to mature.
• Harvest when bolls are dry and fully opened.

Method and Procedure

• In Kenya, cotton is picked manually.
• Sort out grade AR (safi) from grade BR (fifi) into separate containers.

Precautions

• Harvest during dry conditions to prevent dirtying the lint.
• Avoid use of gunny bags to prevent contamination.
• Avoid picking leaves.
• Harvest on a weekly basis.

Harvesting of Pyrethrum

Stage of harvesting

• Takes 3-4 months to mature.
• Harvest the flowers with disc florets which have assumed a horizontal position.

Methods and Procedure

• Pyrethrum is picked manually.
• Flowers are picked by twisting the heads so that no stem is attached.

Precautions

• Clean harvesting should be done.
• Avoid picking leaves.
• Flowers are placed in woven baskets.
• Overblown flowers are picked and thrown off.
• Pick the flowers when the dew is dry.
• Harvested flowers should be taken to the factory the same day.
• Avoid compaction of flowers in the basket.
• Harvesting interval: once in two weeks during the wet season and once in a month during the dry season.

Harvesting Sugarcane

Stage of harvesting

• Takes 14-20 months for the plant crop to mature and 12-16 months for the ratoon crop.
• Sampling of cane is done before harvesting to ascertain the correct sugar content.

Methods and Procedures

• Cut the cane at the ground level to avoid yield loss.
• The green tops are removed from the canes.
• Harvesting machete is used for cutting the cane.

Precautions

• Cane should be harvested immediately at maturity to avoid lowering quality.
• The green tops should be removed immediately after cutting to avoid reduction of sugar content by enzyme invertase.
• Burnt cane should be harvested immediately after burning to prevent rapid inversion to monosaccharides.
• The cane should be processed within 48 hours.

Harvesting of Coffee

Stage of harvesting

• Takes 2-4 years depending on the pruning system.
• Harvest only ripe berries.

Methods and Procedures

• Hand picking is done so that ripe berries can be selected.
• During picking, hooked sticks can be used to bend the tall trees.

Precautions

• Only the uniformly ripe berries should be picked.
• Over-ripe and under-ripe berries should be dried and sold as buni.
• Ripe cherries should be processed on the same day they are picked.

Harvesting Tea

Stage of harvesting

• It takes 2-4 years for tea to mature depending on the method of bringing young tea into bearing.

Method and Procedures

• Tea harvesting is known as plucking.
• Fine plucking – 2 leaves and a bud are removed.
• Coarse plucking – 3 leaves and a bud are removed.
• A straight fitto (straight stick) is used to guide the plucker on the plucking table.
• Tipping is done by cutting off shoots that appear above the fitto.

Precautions

• Plucked tea is placed in woven (well ventilated) baskets to prevent fermenting before it reaches the factory.
• The plucked tea should be kept in a cool place awaiting transport.
• It should be processed within the same day of harvesting.
• Harvesting is done on a weekly basis under wet conditions and once after every two weeks under dry conditions.