AGRICULTURE O LEVEL(FORM FOUR) NOTES – CROP PRODUCTION

THEME 1.0: CROP PRODUCTION

Perennial Field Crop Production

Coffee Production

Scientific name:

• Coffee Arabica
• Coffee Robusta

Family name: Rubiaceae

Origin: The plant originated from Ethiopian highlands and was introduced in East Africa towards the end of the 19th century by French and Roman Catholic missionaries.

Plant Characteristics

• Perennial plant with an economic life of more than 70 years.
• Coffee beans (cherries) contain 1-1.5% caffeine, a stimulant.
• The plant produces two types of branches: vertical and horizontal.
• The plant is self-pollinated.
• The fruit is a berry containing two beans (cherries).
• When ripe, the berry’s outer skin (exocarp) encloses a shiny mucilage (mesocarp), which encloses a rough inner membrane (endocarp or parchment) enclosing two beans. A thin testa called silver skin (pulp) adheres to each bean.

Economic Importance

• Dried beans are roasted, ground, and brewed to make a stimulant beverage.
• Coffee pulp and parchment can be used as manure and mulch after fermentation and decomposition.
• The pulp can be fed to livestock; parchment can be used as deep litter.
• The pulp can also be used for methane gas production.

Distribution in Tanzania

• Kilimanjaro, Arusha, Mbeya – Arabica
• Ruvuma, Kagera, Kigoma, Bukoba – Robusta

Ecological Requirements

• Altitude: 1200m-1800m above sea level.
• Temperature: Optimum 15°C-25°C.
  • High temperatures cause fast, soft growth with extended internodes.
  • Low temperatures shorten internodes, making the tree bushy.
• Rainfall:
  • 760mm-2500mm per annum for Robusta
  • 1500mm-2300mm per annum for Arabica
• Soils: Well-drained, deep fertile soil with pH 5.2-6.2.

Note:

1. Problems associated with low altitude:
   • Continuous production of small flowers.
   • Stunted growth.
   • Crinkling of leaves.
2. Problems associated with high altitude:
   • Climate favors pests like berry borers and diseases like rust.
   • Multiple stem pruning cycle becomes too short.
   • Coffee quality is usually low.

Propagation

Seed Selection

• Seeds must be selected from high-yielding, pest- and disease-free mother plants.
• Harvest mature ripe berries (red in color).
• Pulp and ferment; remove all floating seeds.
• Dry seeds under shade to 14%-18% moisture content.

Nursery Site

• Should be near a water source.
• Should be sheltered from wind.
• Should be on gentle slope.
• Soil should be deep and fertile.
• Remove all weeds and stones.

Nursery Sowing

• Prepare seedbeds 1.2m wide and 10.8m long with 0.9m paths between.
• Pre-germinate seeds, then sow at 15cm x 15cm or 20cm x 20cm spacing, 2.5cm deep.
• Provide shade and water regularly.

Note:

• Plant seeds flat side downward.
• Seedlings are ready for transplanting after 1 to 1.5 years when 30cm tall.

Transplanting

• Prepare field 6 months before rainy season.
• Remove all plant/tree roots to avoid Armillaria mellea fungus causing root disease.
• Prepare holes 3 months before rainy season.
• Holes size: 60cm x 60cm; spacing 2.7m x 2.7m (Arabica) or 3.3m x 3.3m (Robusta) if no shade trees.
• If shade trees used, spacing increases to 14m x 14m (Arabica) and 22m x 22m (Robusta).
• Two to three weeks before transplanting, mix 1 debe topsoil and 1 debe farmyard manure or compost in holes.
• Mark hole center with a peg for seedling placement.
• Do not bend roots during transplanting.
• Apply mulch around stem but not touching it.

Advantages of Shade Trees in Coffee Fields

• Reduce evapotranspiration.
• Most shade trees are leguminous, supplying nitrogen.
• Modify climate.
• Reduce soil erosion.
• Foliage acts as mulch before decomposition and manure after.
• Reduce wind effects.

Common Shade Trees

• Grevillea robusta
• Albizia spp.
• Cordia abyssinica

Field Management

Weeding

1. Common weeds: couch grass, star grass, Kikuyu grass.
2. Weeding by cultural methods: mulching, cultivation with simple tools, slashing.
3. Chemical control: herbicides such as paraquat, atrazine, dalapon.

Fertilizer Application

1. Soils with pH below 5: apply CAN (Calcium Ammonium Nitrate).
2. Soils with pH 5-6.5: alternate CAN and NPK yearly.
3. Soils with pH above 6.5: apply SA (Sulphate of Ammonium) or urea.
4. Application rate depends on soil nutrient level, ranging from 90kg N/ha to 255kg N/ha.

Pruning

Removal of dead, pest- and disease-affected, and old branches.

Purpose:

• Improve light penetration.
• Improve spacing.
• Discourage pests and fungal diseases.
• Facilitate pesticide application.
• Facilitate harvesting.
• Promote formation of high-quality berries.
• Encourage vigorous growth.

Types of Pruning

1. Single stem pruning: retain original stem, height 1.5-1.8m.
2. Multiple stem pruning: retain 2-4 upright stems.

Stages of Pruning

1. Formative stage: establish main tree framework for pruning.
2. Actual pruning stage: routine encouragement of vigorous growth and heavy cropping.

Pruning of Arabica Coffee

Grow Arabica coffee as single stem system. Pruning aims to:

• Supply healthy wood for next season’s crop.
• Maintain balance between leaf area and crop.
• Prevent overbearing and dieback.
• Reduce biennial bearing.
• Maintain good tree shape.

Desuckering

Year 1

• Desucker to maintain single stem system and avoid competition from suckers.
• Remove ‘fly crop’ fruit (early fruit competing with plant/root development) as they appear.

Year 2

• Desucker to remove drooping primary branches touching ground; cut back to nearest secondary branch.
• Remove secondary branches within 20 cm of main stem.
• Remove all fruit as they appear (fly crop).

Year 3

• Trees allowed to crop.
• Cap main stem by cutting above side primary shoot about 1.6 m from soil.
• Desucker to remove drooping primary branches touching ground; cut back to nearest secondary branch.
• Remove secondary branches within 20 cm of main stem.
• Maintain well-spaced secondary branches on each primary branch.
• Remove dead, weak, spindly, pest- or disease-damaged branches.

As plants grow crowded and production declines, alternate trees can be stumped by cutting at knee height (~50 cm). When these produce again after two years, stump remaining trees.

General pruning and desuckering over years 1 and 2. Capping during year 3. Newly capped tree photo above.

Rejuvenation (Change of Cropping Cycle)

Regular rejuvenation pruning is needed every six to seven years depending on tree vigor and yield to maintain new fruiting wood. Without renewal, yield declines.

Two rejuvenation methods:

• Side pruning
• Full stumping

Side Pruning

Remove one side of the tree, train a new sucker, then remove the other side two years later. Recommended for all growers as only 50% crop loss occurs during the two-year period.

Two years before stumping, remove all branches on eastern side after harvest. Select a new sucker 30-45 cm from soil and train it by thinning until bearing crop.

Two years later, stump older stem above new stem. Cut at 45° angle; do not cut straight.

Remove all young suckers from main stem.

Remove secondary branches within 15 cm of main stem.

Remove dead, diseased, pest-attacked, and non-bearing branches.

Final result should be about 170 cm tall and wide enough for light penetration.

Pest and Disease Control

Pests

1. Leaf miner: Leucopterus spp.
   Damage: Larva bores into leaves, feeding on palisade tissues causing brown blotches.
2. Antestia bug: Sucks berries causing longitudinal/zebra stripes and defoliation of buds.
3. Other pests:
   • Berry moth
   • Mealy bugs (sucking insects)
   • White scales
   • Thrips

Control: Timely spraying of insecticides such as Dursban, Dicofol, Dieldrin at 1 litre per hectare.

Diseases

1. Coffee berry disease
   Cause: Fungus Colletotrichum coffeanum.
   Symptoms:
   • Necrotic lesions forming brownish rings on leaves.
   • Fruits become blackish, shriveled, and drop.
   • Spread by raindrops or wind.

   Control:

   • Prune affected branches to reduce humidity.
   • Remove fruits from seasonal flowering.
   • Supply proper nutrients to increase resistance.
   • Use fungicides such as Cobox 500WP, Sandox 500WP, Nodox 500WP, Perenox, Bravo.
2. Coffee leaf rust
   Cause: Fungus Hemileia vastatrix.
   Symptoms: Yellow pustules on leaves causing defoliation.
   Control:
   • Cultural control.
   • Chemical control using fungicide such as Bravo.

Other Diseases

• Wilting (dieback) – Fusarium stiboides
• Armillaria root rot – Armillaria mellea

Harvesting

• Hand-pick cherries when uniformly ripe.
• Overripe berries (dark) are difficult to pulp.
• Unripe berries (green) lack sufficient mucilage for pulping.
• Mixed ripeness causes uneven fermentation.
• Yellow berries produce poor quality.

Processing Methods

Two methods:

1. Dry method (Buni)
   • Berries left to dry on tree then collected and ground as Buni.
   • Berries can be dried in sun on raised trays.
2. Wet method (Arabica)
   • Cherries pulped with water to separate beans from skin.
   • Parchment coffee fermented 2-4 days to remove mucilage by enzymes.
   • Beans washed to remove broken mucilage.
   • Drying under sun.

Yield: Average 800kg/ha to 1250kg/ha.

Note:

• Robusta coffee grows at low altitudes (1100-1400m). It has vigorous growth and large coarse, corrugated leaves, unlike Arabica’s flat leaves.
• Robusta bears heavily if not attacked by pests and diseases.
• Many growers leave Robusta unpruned as it does not suffer overbearing like Arabica.
• Robusta is sold as sundried cherry, hulled at factories.

Yield: 1900kg/ha or more.

Tea

Scientific name: Camellia sinensis

Varieties:

• Sinensis
• Sinensis Assamica

Origin: China

Major producers: India, Taiwan, Argentina, China, Kenya, Thailand, Malawi, Mozambique, Uganda, Zaire, Mauritius, Tanzania.

Distribution in Tanzania: Tukuyu, Mbeya, Mufindi.

Uses:

• Beverage.
• Medical purposes (fluorine extraction).

Characteristics of Assam Tea (Camellia sinensis var. assamica)

• Grows up to 9m high.
• Adapted to tropics.
• Fast growth.
• High yield.
• Pale green leaves.
• Flowers borne in clusters of 2 to 4.

Characteristics of China Tea (Camellia sinensis var. sinensis)

• Dwarf, max height 4.5m.
• Adapted to subtropics.
• Slow growth.
• Narrow, serrated dark green leaves.
• Low yield.
• Flowers borne singly.

Ecological Requirements

• Altitude: 1500-1800m above sea level.
• Temperature: 20-25°C.
• Rainfall: 1500-1700mm per annum.
• Soils: Well-drained, acidic pH 4-6.

Field Management

Propagation

• Seeds
• Vegetative

Using Seeds

• Obtain seeds from desirable plants.
• Pre-germination needed due to rough seed coat for uniform germination.

Note:

• Seeds have high segregation; cuttings preferred.
• Floatation test: discard floating seeds after 24 hours in water.
• Pre-germinate seeds by covering with wet sacks; plant 2.5cm deep at 13-15cm spacing.
• Seedlings ready at 12-13cm height after 2 years.
• Lift seedlings and cut above ground to 10cm stump.

Cuttings

• Mother trees grown 6 months after pruning for long stems.
• Use single leaf internode cuttings; discard top 2-3 internodes and base portion.
• Top cut near auxiliary buds; lower cut slanting.
• Plant cuttings in 25cm deep polythene tubes.
• Ready for transplanting when roots reach tube bottom and 20cm high (6-10 months).
• Immerse cuttings in water before planting to maintain turgidity.

Land Preparation

Site Selection

• Avoid settlements, cattle bomas, charcoal burning sites due to high pH.
• Dig holes 30cm deep and 30cm x 30cm at 1.5m x 0.7m or 1.2m x 0.9m spacing.
• Plant shade trees along boundaries: Hokea saligna, Grevillea robusta, Spathodea nilotica.

Fertilizer Application

• Tea leaves take 62kg nitrogen per 1132 leaves; nitrogen applied 3 months after planting until economic level using NPK 25:5:5.
• Note: Avoid CAN fertilizers as they limit uptake.
• Phosphorus deficiency causes dieback; potassium deficiency causes leaf scorching and defoliation.
• Sulfur deficiency causes yellowing leaves.
• Apply 110-120kg N/ha and 27kg P2O5/ha.

Mulching

Important at early stages; later plants provide mulch through pruning.

Pruning / Frame Formation / Plucking Table

Two stages:

1. Formative
2. Pegging

Formative Stage (Frame Formation)

• Stimulate lateral growth sideways to form wide, continuous plucking table frame.
• Start when plants reach 30-35cm after one year; cut plant 15cm from ground.
• Lateral roots grow to pencil thickness; cut plant to 27cm from ground.
• Takes 2-3 years to reach convenient height.
• Generally, 12-13cm added yearly until 60cm tall.

Pegging

• After frame formation, allow new shoots to grow 3 months, then remove by tipping (remove 3 leaves and a bud from shoot tips above required height).
• Done by hand using wooden frame for correct height.
• Repeat every 2-3 weeks; maintain foliage 20-30cm deep.
• Prepare pegs for each shoot.
• Peg two rows of branches on either side of stem so stem radiates outward.

Maintenance Collage

Removal of Bhanjhi Shoots

Dormant shoots with hard leaves due to prolonged leaf production; remove when they appear above plucking table.

Pests

• Leaf miner
• Thrips: suck cell sap causing leaf defoliation.
• Mites

Disease

• Armillaria root rot causing root decay is common in East Africa.

Control:

• Proper land preparation.
• Remove affected plants.

Harvesting (Tea Plucking)

Plucking: Harvesting tea leaves.

Methods of Plucking

1. Fine plucking: tip 2 leaves and a bud; produces high-quality tea.
2. Coarse plucking: pick more than 2 leaves and a bud; reduces plucking frequency.
3. Hard plucking: break shoot tip at plucking table height; reduces maintenance foliage depth.
4. Light plucking: pick 2 leaves and a bud after 3 leaves grow above plucking table; done once or twice a year.

Note: Plucking interval is 5-7 days depending on conditions and method.

Yield: Average 1500kg leaves per hectare.

Cardamom

Scientific name: Elettaria cardamomum

Uses:

• Dry fruits used as spice.
• Used as medicine.
• Leaves flavor bread, cakes, etc.
• Aromatic stimulant in beverages like tea.
• Used in cosmetics preparation.

Distribution

• Tanga, Zanzibar, Rungwe (Mbeya).

Ecological Requirements

• Altitude: 750-1500m above sea level.
• Rainfall: 1500mm-2500mm per annum.
• Temperature: 10°C-30°C.
• Soils: Deep fertile soil rich in humus.
• pH: Slightly acidic to neutral.

Propagation

• Vegetative by rhizome division in small-scale production.
• Seeds used in large-scale production.
• Collect seeds from ripe capsules, dry in shade, sow immediately; remove mucilage by rubbing in ashes before drying.
• Transplant seedlings at 15cm tall (3-4 months) at 1.5m x 3m spacing.

Field Management

• Weeding, mulching, removal of old/dry stems, gap filling, shade regulation, manuring.
• Cardamom bears after 3 years; full bearing at 4-5 years.
• Economic life: 10-15 years.

Pests

Thrips (Thrips tabaci)

Damage: Suck cell sap.

Control: Insecticides such as Dursban, Dursam.

Diseases

1. Leaf rot: bacterial; causes leaf rotting.
   Control: Field hygiene, crop rotation.
2. Marble disease.

Harvesting

• Harvest fruits just before fully dry to prevent capsule splitting.
• Sun-dry or artificially heat treat fruits.
• Winnow dried capsules to remove pedicels and foreign material.

Yield

Dry capsule: 112-200 kg per hectare per annum.

Market: Local towns and export.

Coconut

Scientific name: Cocos nucifera

Origin: Asia and Southern Europe (East India)

Distribution: Coastal areas: Tanga, Dar es Salaam, Morogoro, Pwani.

Varieties

Classified by height:

1. Tall varieties
   • Most popular in East Africa.
   • Nut germination after 2.5-3 months.
   • Strong stems up to 35m.
   • Produce 50-80 nuts/year for 60-100 years.
   • First bearing at 5-6 years.
   • Maximum production after 9-10 years.
   • Large nuts with thick copra and high oil content.
2. Dwarf varieties
   • Germinate in 1.5-2 months.
   • Short economic life (30-40 years).
   • Maximum production starts at 5-6 years.
   • Small nuts with thin copra and low oil content.
   • Produce 150-200 nuts/year.
   • Preferred for easy harvesting, high yield, and resistance to lethal yellow disease.

Disadvantages of Dwarfs

• Susceptible to strong winds and dry conditions.
• Susceptible to rhinoceros beetle due to succulent nature.
• Limits inter-cropping.

Examples

• Tall: East African tall, West African tall, Polynesian African tall.
• Dwarf: Malaysian yellow dwarf, Malayan red dwarf, Cameroon yellow dwarf, Brazilian green dwarf, Equatorial green dwarf, Mawa, Camwa.

Uses

• Oil from mature dry nuts (copra) contains 65-70% oil; used for cooking and softening blankets.
• Coconut juice (milk) for drinking.
• Palm wine (mnazi) from unopened young inflorescence.
• Leaves for thatching and basket making.
• Midrib for fences, firewood, brooms.
• Mattresses from coarse brown fibers.
• Endocarp used for cups and calabashes.
• Poles for building houses.

Ecological Requirements

• Altitude: 0-1000m above sea level.
• Rainfall: Well distributed, minimum 1200mm, optimum 2500mm.
• Temperature: 27°C-28°C.
• Soil: Deep, well-drained, aerated light sandy soils, pH 5.0-8.0.

Propagation

Nursery

• Near permanent water source.
• Select medium-sized nuts for faster water absorption.
• Plant nuts horizontally in trenches, leaving small portion unburned.
• Frequent irrigation.
• Seedlings ready for transplanting at 6 leaves (2 months old).

Main Field

• Burn old stumps and leaves to control rhinoceros beetle.
• Mix FYM, TSP, CAN, MCPA, Magnesium Sulphate in 6-12m holes.
• Spacing: 9x9m for tall, 7x7m for dwarf varieties.
• Deep planting; 120-140 plants per hectare.

Preparation and Planting

• Propagate by seed nuts planted in nursery trenches; maintain seedlings 9-12 months until 3-4 leaves.
• Transplant at start of rains; dig 60cm deep holes days before planting; plant nuts/seedlings 30-45cm below surface.

Field Maintenance

• Apply NPK 500g per tree per year.
• Apply nitrogen to increase flower number.
• Weed around stem using hand hoes.
• Apply herbicides such as paraquat, atrazine.

Pest and Disease Control

Pests

1. Rhinoceros beetle: Oryctes monoceros
   Damage:
   • Attack terminal bud.
   • Destroy unopened leaves and growing point.
   • Leaves develop v-shaped notches.
   • Leaves dry up.

   Control:

   • Burn decaying trunks, stems, leaves.
   • Use wire to pierce beetle.
2. Coreid bug: Pseudotheraptus wayii
   Damage: Suck juice from young nuts causing cracking and dropping.
   Control: Biological control by Oecophylla longinoda (Majimoto ants).
3. Termites and other sucking insects.
   Control: Dust Aldrin around trees.

Diseases

1. Bole rot
   Cause: Fungus Marasmiellus cocophilus.
   Symptoms: Yellowing leaves and wilting.
   Control: Avoid root damage and infected seedlings.
2. Lethal yellow disease (viral)
   Symptoms: Light brown irregular lesions starting at young leaf tips.
   Control: No chemical control; uproot affected plants.

Harvesting and Yield

• First bearing 5-10 years after transplanting.
• Full bearing 10-18 years.
• Nuts harvested 7-10 months after flowering.
• Harvest at full maturity for copra production.
• Yield: 15-30 nuts per tree.

Products from Nuts

• Margarine, oils, soaps, mattress stuffing, baskets.
• Dried leaves used for thatching mats and baskets.

Cashew Nuts

Scientific name: Anacardium occidentale

Origin: America

Distribution: Ruvuma, Lindi, Tanga in Tanzania.

Uses

• Cashew nut apple used in alcohol brewing.
• Apple edible, provides vitamins.
• Dry stems and branches used as firewood.
• Nuts used as food.
• Roots used as medicine.
• Provides foreign exchange due to oil content used for body warmth.
• Provides oil.

Ecological Requirements

• Altitude: 0-750m above sea level.
• Temperature: Favors up to 35°C.
• Rainfall: 750-900mm per annum.
• Soil: Well-drained, acidic pH 4.5-6.5.

Propagation

Propagated directly by seeds (nuts). Also by air layering and grafting, but seeds preferred. Heavy seeds are most viable. Prepare seed beds by clearing and burning before sowing.

Sow at start of rains. Dig holes 30cm wide, 5.0-7.5cm deep. Plant seeds 2.5cm apart in holes. Spacing 12m x 12m or 15m x 15m.

Field Management

• Provide temporary shade for young seedlings.
• Select medium-sized nuts for faster water absorption.
• Plant in trenches horizontally, leaving small portion unburned.
• Frequent irrigation.
• Seedlings ready for transplanting at 6 leaves (2 months old).
• Burn old stumps and leaves to control rhinoceros beetle.
• Mix FYM, TSP, CAN, MCPA, Magnesium Sulphate in 6-12m holes.
• Spacing: 9x9m for tall, 7x7m for short varieties.
• Deep planting; 120-140 plants per hectare.
• Propagate by seeds planted in nursery trenches; maintain seedlings 9-12 months until 3-4 leaves.
• Transplant at start of rains; dig 60cm deep holes days before planting; plant nuts/seedlings 30-45cm below surface.
• Apply NPK 500g per tree per year.
• Apply nitrogen to increase flower number.
• Weed around stem using hand hoes.
• Apply herbicides such as paraquat, atrazine.

Pest and Disease Control

Pests

1. Rhinoceros beetle: Oryctes monoceros
   Damage:
   • Attack terminal bud.
   • Destroy unopened leaves and growing point.
   • Leaves develop v-shaped notches.
   • Leaves dry up.

   Control:

   • Burn decaying trunks, stems, leaves.
   • Use wire to pierce beetle.
2. Coreid bug: Pseudotheraptus wayii
   Damage: Suck juice from young nuts causing cracking and dropping.
   Control: Biological control by Oecophylla longinoda (Majimoto ants).
3. Termites and other sucking insects.
   Control: Dust Aldrin around trees.

Diseases

1. Bole rot
   Cause: Fungus Marasmiellus cocophilus.
   Symptoms: Yellowing leaves and wilting.
   Control: Avoid root damage and infected seedlings.
2. Lethal yellow disease (viral)
   Symptoms: Light brown irregular lesions starting at young leaf tips.
   Control: No chemical control; uproot affected plants.

Harvesting and Yield

• First bearing 3 years after sowing.
• Full bearing 8-10 years after sowing.
• After fruit (cashew apple) ripens, it drops with nut for collection.
• Cashew apple may sprout if left on ground or be eaten/used in brewing.

Processing

• Major processing center in Tanzania: TANITA.
• After apple and nut drop, dry nut 3-4 days.
• Roast after drying.
• Remove outer cover by bursting; extract kernel for eating.

Yield

600-1000kg per hectare (590-1100kg range).

Note: Use motorized sprayers with sulfur compounds to kill sucking insects that hinder production.