UNIT 10: Crop Husbandry Practices

Success Criteria

• Prepare land for crop production.
• Describe activities for preparing land for crop production.
• Select crops and varieties suitable for their environment.
• Select good seed for planting.
• Plant the selected crops in a school garden.
• State the importance of weed control.
• Describe weeding in the selected crops.
• Apply fertilizers to crops correctly.
• Describe major diseases of the selected crops.
• Discuss the losses caused by diseases.
• Describe disease control practices.

Land Preparation

Land preparation encompasses all activities undertaken on land to create a suitable seedbed (tilth) for planting. This involves achieving the correct depth, suitable clod size, and soil looseness to facilitate seed germination and plant development.

Importance of Land Preparation:

• Removes existing vegetation that could interfere with subsequent field activities.
• Buries organic matter into the soil, which decomposes into humus, improving soil fertility.
• Helps to kill disease-causing organisms present in the soil.
• Controls perennial weeds.
• Improves the physical condition of the soil, allowing for better root penetration and development.
• Enhances water infiltration into the soil.
• Restores leached plant nutrients back to the surface.

Operations in Land Preparation:

1. Land Clearing:

   • Description: Removal of unwanted vegetation to make land cultivatable.
   • Tools: Hoes, machetes, slashers, tractor-drawn implements (disc ploughs, chisel ploughs, mouldboard ploughs, rotavators). Herbicides (e.g., Roundup) can also be used.
   • Methods: Slashing grass, felling trees and stumping (removing tree stumps, often with machines for large-scale farmers).
   • Note on Burning: Setting fire is not recommended as it kills beneficial microorganisms and can cause uncontrolled destruction.
   • Importance:
     • Facilitates subsequent operations by removing obstructions like tree stumps.
     • Helps drive away pests hiding in bushes and removes trees that harbor pests (monkeys, rodents, snakes, birds) or shade crops.
     • Essential in humid, bushy areas like wetlands.

2. Ploughing or Primary Cultivation (Tilling):

   • Description: The initial opening of land after clearing or a previous cropping season.
   • Tools: Disc plough, rotavators, tractor-mounted mouldboard plough, ox-plough. Hoes are used by small-scale farmers.
   • Importance:
     • Makes subsequent operations easier.
     • Loosens the soil for improved aeration and water infiltration.
     • Controls weeds (e.g., rhizomatous weeds) by burying or uprooting them.
     • Buries crop residues, allowing them to decompose and add nutrients.
     • Eases penetration of crop roots.
     • Controls pests and diseases by exposing them to sun and predators.
   • Factors Influencing Tool Choice:
     • Type of tilth required: Finer tilth for small seeds.
     • Depth of cultivation: Root crops need deeper tillage.
     • Type of soil: Heavy machinery for hard, dry clayey soils; forked hoes for wet soils.
     • Soil moisture content: Affects ease of operation.
     • Size of land: Hand tools for small plots, heavy machines for large areas.
     • Capital: Hand/animal-drawn tools are cheaper.
     • Topography: Hand/animal-drawn tools for varying slopes, tractors for flat land.
   • Timing:
     • Virgin land: Cultivate during the dry season to scorch plants completely.
     • Previously cropped land: Till soon after harvesting when land is not excessively dry.

3. Secondary Cultivation or Harrowing:

   • Description: Breaking large soil lumps or clods into finer particles after primary cultivation.
   • Tools: Forked hoes, rakes, regular ploughs, ox-ploughs (small-scale). Disc harrows, cultivators (rotavators), spring tine harrows, spike tooth harrows (large-scale).
   • Factors Determining Frequency:
     • Initial seedbed condition: Rough primary cultivation or virgin land may need more harrowing.
     • Size of planting materials: Small seeds require a finer tilth, thus more harrowing.
     • Slope of the land: Reduce harrowing on steep slopes to prevent soil pulverization and erosion.
     • Moisture content of the soil: Wet soils may require more operations; dry soils less to conserve moisture.
     • Type of primary cultivation implement: Implements like disc ploughs that leave larger clods and unburied trash require more secondary operations.
   • Importance:
     • Breaks large soil clods into finer particles.
     • Destroys weeds that grow after primary cultivation.
     • Prepares a seedbed with fine tilth.
     • Facilitates correct planting depth for small seeds.
     • Effectively incorporates organic materials (e.g., crop residues) into the soil.

4. Tertiary Cultivation or Ridging Construction:

   • Description: Creation of raised seedbeds (ridges) by heaping soil in continuous lines. The space between ridges is a furrow.
   • Orientation: Ridges should be made across slopes or follow contours to prevent soil erosion. (Ridges along slopes create water channels, leading to gullies).
   • Note: Some crops may not require ridging. This stage is “miscellaneous” as it depends on the crop type (e.g., root crops grow well in ridges).
   • Reasons for Proper Ridging:
     • No wastage of land (efficient use).
     • Furrows help to hold water.
     • Reduces competition for growth resources among plants.
     • Ensures adequate vegetative cover, preventing soil erosion and excessive evaporation.
   • Importance of Ridges:
     • Encourages free expansion of tubers and pods in legumes.
     • Makes harvesting easier.
     • Furrows help to conserve moisture.
     • Encourages drainage in waterlogged soil.
   • Spacing: Depends on crop type/variety (e.g., most crops: 91cm; groundnuts: 45-80cm; Burley tobacco: 125cm).
   • Construction Materials: Hoes, tape measure, string, pegs, A-frame (for measuring gradient/contours).
     • A-frame: A tool made from two bamboos nailed at the top with a crossbar; a suspended string indicates a level ground when it balances through the center of the crossbar.

5. Box Ridges (Tie Ridges):

   • Description: Structures constructed on alternate sides between ridges, shorter than ridges, allowing excess water to overflow to the next box ridge during heavy rainfall.

Selecting Crops and Varieties

Factors influencing crop and variety choice are crucial for successful farming.

1. Climatic Factors:

• Rainfall:
  • High Altitude (1300-1800 mm/year): Mulanje, Thyolo, Misuku Hills, Nyika, Viphya. Crops: tea, rubber, maize varieties (PAN 77, SC 709, SC 715, SC 717, PHB30G19).
  • Medium Altitude (800-1000 mm/year): Lilongwe-Kasungu plains, Mzimba plains. Crops: maize, tobacco, groundnuts, maize varieties (PAN 57, PAN 63, PHB30G97, DK 80-73).
  • Rift Valley/Low Altitude (300-700mm/year): Lake shore, Shire Valley (Salima, Nsanje, Chikwawa, Neno). Crops: sorghum, millet, maize varieties (SC 513, SC 403, SC 533, DK 8033, Pan 4M-19).
  • Rainfall Distribution: Areas with long rainy seasons (Thyolo, Mulanje, Chitipa, Nkhata Bay, Eastern Nsanje) are suitable for perennial crops like bananas.
  • Rainfall Reliability: Climate change necessitates considering drought or excessive rains when selecting crops.
• Temperature:
  • Optimum temperature is vital for growth, maturity, and ripening.
  • Some crops (e.g., coffee, sorghum) thrive in high temperatures (e.g., Salima, Chikwawa).
  • Very high temperatures lead to excessive evaporation and wilting.
• Sunlight (Radiation): Essential for photosynthesis, chlorophyll synthesis.
  • Light Intensity: Rate at which sunlight spreads. Photosynthesis increases with intensity but declines if chlorophyll is damaged.
  • Light Duration (Photoperiod): Relative length of light and dark periods.
    • Long-day plants: Do well with long light periods.
    • Short-day plants: Do well with short light periods (e.g., soya beans, tobacco, rice).
    • Day-neutral plants: Thrive irrespective of light periods.

2. Soil Factors:

• Soil Structure: Influences water movement and aeration.
• Soil Texture: Affects water circulation, drainage, and aeration. Fine soil is poorly drained (not good for root crops). Sandy soil is porous, good for aeration and root crops.
• Soil pH: Affects nutrient availability.
• Soil Profile (Depth): Affects root penetration and development. Shallow soil is unsuitable for root crops.

3. Crop Varieties (Examples):

• Maize: PAN 57, 63, 77; PHB30G97; DK 8021, 8033, 8051, 8071; SC 709, 715, 717; PHB30G19; ZM 309, 523. Choose varieties suitable for local conditions (e.g., early maturing for short rainy seasons).
• Common Groundnuts:
  • CG7 or Red Skin: Common in Thyolo, Balaka, Mchinji. Deep red skin, uniform size, good for confectionary (peanut butter, oil).
  • Chalimbana: Light dark tan color, rich flavor, suitable for confectionary.
  • Manipintar: White and red patches, irregular shapes and sizes.
  • Baka, Nsinjiro.

Selecting Good Seed for Planting:

• Qualities of a Good Seed:
  • Plump or large enough (indicates sufficient food reserves).
  • Whole, not broken.
  • Not rotten.
  • Disease-free or shiny appearance.
  • Certified seed.
  • Suited to the environmental conditions of the area.
  • High purity, not mixed with contaminants.
• Qualities of Good Vegetative Material (bulbs, tubers, stem cuttings, vines):
  • Fresh and succulent.
  • Presence of healthy buds and nodes.

Planting Selected Crops in a School Garden

1. Time of Planting:

• Maize should be planted with the first rains at the onset of the rainy season (e.g., November in Malawi).
• Benefits of Early Planting:
  • Plants make maximum use of rains.
  • Crops often escape late-season pests, diseases, and severe weed pressure.
  • Crops efficiently compete with weeds.
  • Crops benefit from the “nitrogen flush” (initial release of nitrogen with first rains).
  • Leads to early harvesting, allowing farmers to sell at higher prices.

2. Marking Out Planting Stations:

• Done before the rainy season, often accompanied by fertilizer application.
• Stations are marked according to recommended distances (e.g., 90cm apart, three plants per station for maize; 75cm for dwarf maize varieties; Sasakawa: 30cm for tall, 25cm for dwarf).
• Use a string and sticks to mark stations, inserting sticks for easy identification during planting.
• Groundnut spacing depends on variety (e.g., bunch types like Malimba: 10cm apart, one plant/station; runner types like Chalimbana: 15cm apart, one seed/station).
• Measuring Spaces: Use a tape measure or a stick cut to the correct dimension. Two sticks with a string can hasten the process. This ensures the correct plant population for efficient resource utilization and high yield.

3. Calculating Number of Seeds per Given Area:

• Information Needed: Area of the field, distance between planting stations, number of seeds per station.
• Formula: Number of seeds required = (Area of field × No. of seeds per station) / (Area occupied by each station)
• Example (Germination Percentage):
  • Calculate germination percentage if 40,000 seeds were planted and 108 failed.
  • Seeds germinated = 40,000 – 108 = 39,892.
  • Germination % = (Number of seeds germinated / Total number of seeds planted) × 100%
  • Germination % = (39,892 / 40,000) × 100% = 99.7%

4. Correct Planting Depth:

• Importance: If seeds are planted too deeply, seedlings may fail to emerge as all food reserves are depleted before reaching the surface.
• Recommended Depth for Maize: 7.5 to 10cm deep.

Weed Control

Weeds are unwanted plants that grow together with crops, including any other crops that grow without being intentionally planted. Common weeds include witch weed, Cynodon dactylon (kapinga), Commelina benghalensis (khovani), Bidens pilosa (chisoso), Tridax procumbens, and Rottboellia exaltata (msonthi).

Disadvantages of Weeds:

• Reduce crop quality and quantity due to competition for food, water, light, and space.
• Harbor pests that destroy crops.
• Act as alternate hosts for disease-causing organisms.
• Increase production costs due to labor needed for removal.
• Deplete soil fertility by excessive nutrient uptake.
• Block irrigation channels.

Weeding (Removal of Weeds):

1. Cultural Methods:

   • Early Planting: Crops develop earlier, gaining a competitive advantage before weeds establish.
   • Correct Plant Spacing: Ensures crops provide sufficient vegetative cover to suppress weeds.
   • Crop Rotation: Breaks the life cycle of specific weeds.
   • Mulching: Covering soil with vegetative materials to provide shade, suppressing weed growth.

2. Mechanical/Physical Methods:

   • Light hoeing.
   • Banking (earthing up).
   • Uprooting (manual removal).
   • Slashing.

3. Biological Methods:

   • Introducing animals that eat or destroy weeds (must be controlled to prevent crop damage).

4. Legislative Method:

   • Use of Acts of Parliament or laws to control specific problematic weeds (e.g., Namasupuni).

Applying Fertilizers to Crops Correctly

This section was not fully detailed in the provided text. To complete this point as per success criteria, general principles would include:

• Soil Testing: Apply fertilizers based on soil test recommendations to address specific nutrient deficiencies.
• Right Fertilizer Type: Use fertilizers appropriate for the crop’s nutritional needs and growth stage (e.g., basal fertilizers at planting, top-dressing during growth).
• Right Rate: Apply recommended amounts to avoid over- or under-fertilization.
• Right Time: Apply at optimal growth stages for nutrient uptake.
• Right Method: Use appropriate application methods (e.g., broadcasting, band application, side-dressing).

Describing Major Diseases of Selected Crops & Discussing Losses

This section was not detailed for specific crops in the provided text. To complete this point as per success criteria, general principles would include:

• Identification: Students should be able to identify common diseases affecting crops relevant to their region (e.g., Maize Streak Virus, Groundnut Rosette Disease, Tobacco Mosaic Virus).
• Losses Caused by Diseases:
  • Yield Reduction: Direct damage to plant parts, reducing photosynthetic capacity and fruit/grain development.
  • Quality Deterioration: Affects appearance, taste, nutritional value, and marketability of produce.
  • Increased Production Costs: Due to expenditures on fungicides, resistant varieties, and labor for disease management.
  • Reduced Market Value: Diseased produce fetches lower prices or becomes unsalable.
  • Food Insecurity: Widespread outbreaks can lead to significant crop losses, threatening food security at household and national levels.

Disease Control Practices

This section was not detailed for specific crops in the provided text. To complete this point as per success criteria, general principles would include:

• Cultural Practices:
  • Crop rotation to break disease cycles.
  • Use of disease-free seeds/planting materials.
  • Timely planting and harvesting.
  • Proper field sanitation (removing diseased plant debris).
  • Optimizing plant spacing and nutrient management to improve plant vigor.
• Resistant Varieties: Planting crop varieties bred for resistance to common local diseases.
• Chemical Control: Judicious use of fungicides or other appropriate chemicals as a last resort, following recommended guidelines.
• Biological Control: Using beneficial microorganisms or natural predators to suppress disease-causing pathogens.
• Quarantine and Legislation: Restricting movement of diseased plant material to prevent spread to new areas.