Introduction
- A piece of land that is prepared is known as a seedbed.
- A seedbed is a piece of land prepared and ready to receive planting materials.
Seedbed Preparation
Reasons for Seedbed Preparation
- To enable water to infiltrate the soil effectively.
- To kill weeds that compete with crops for nutrients and water.
- To improve soil aeration, allowing roots to access oxygen.
- To destroy pests and diseases present in the soil.
- To incorporate organic matter into the soil, enhancing fertility.
- To facilitate easy planting of seeds or seedlings.
- To allow roots to penetrate the soil easily for better growth.
Operations in Land Preparation
Land Clearing
- Clearing of land is necessary when:
- Opening up virgin land for cultivation.
- A stalk-growing crop was previously planted.
- There is a long interval between primary and secondary cultivation.
- The land was left fallow for a long time.
Procedure
- Tree felling and removal of stumps and roots.
- Burning of cleared vegetation.
- Slashing of bushes and weeds.
- Use of chemicals to kill unwanted plants.
Note: Burning should be avoided where possible because it:
- Leads to loss of valuable organic matter.
- Kills beneficial soil organisms.
- Destroys soil structure and depletes plant nutrients.
Primary Cultivation
- This is the initial breaking of the land.
- It is done early before the onset of rains to:
- Allow time for soil organisms to decompose organic matter.
- Permit gaseous exchange, where carbon dioxide diffuses out and oxygen enters the soil.
- Enable subsequent operations to be carried out in a timely manner.
Reasons for primary cultivation:
- To remove existing weeds.
- To bury organic matter, enhancing soil fertility.
- To open up the soil for better infiltration of water and air.
- To expose pests and disease-causing organisms to the surface.
- To soften the soil, making planting easier.
Operations in primary cultivation
- Hand digging
Use of hand tools
- Jembes (hoes)
- Mattocks
- Fork-jembes
Mechanical cultivation
Use of mouldboard ploughs:
- Disc ploughs
- Chisel ploughs
- Subsoilers
- Rippers
Use of Ox-Ploughs
These can be drawn by:
- Oxen
- Donkeys
- Camels
Depth of Cultivation
Depends on:
- The type of crop to be planted and the size of the seed.
- The implements available for cultivation.
- The type of soil present on the land.
Choice of Implement
Determined by:
- The condition of the land.
- The type of tilth required and the type of crop.
- The desired depth of cultivation.
Secondary Tillage
- These are refinement practices on the seedbed that follow primary cultivation.
- Secondary tillage is also known as harrowing.
Reasons for secondary tillage:
- To remove germinating weeds.
- To break soil clods and produce the required tilth for planting.
- To level the seedbed for uniform planting.
- To incorporate organic matter or manure into the soil.
Factors determining the number of secondary cultivations:
- Soil moisture content at the time of cultivation.
- Size of the planting materials.
- Condition of the soil after primary cultivation.
- Slope of the land, which affects water runoff and soil stability.
Tertiary Operations
- Ridging
- The process of digging soil along a continuous line and heaping it on one side to produce a furrow and a bund (ridge).
- Ridging is important for root crops as it allows root expansion and aids in soil and water conservation.
- Rolling
- This involves compacting the soil to produce a firm surface, which increases seed-soil contact and helps prevent wind erosion.
- Levelling
- Creating an even, uniform surface that promotes uniform planting and efficient water distribution.
Subsoiling
- This is deep cultivation into the subsoil layer to break up any hardpan that might have developed.
It is done for the following reasons:
- To facilitate drainage by breaking compacted layers.
- To bring up leached nutrients to the surface where roots can access them.
- To increase aeration of the soil, improving root respiration.
- To improve root penetration into deeper soil layers.
- The implements used include chisel ploughs and subsoilers.
Minimum Tillage
- This involves applying a combination of farming practices aimed at reducing soil disturbance.
Examples include:
- Use of herbicides to control weeds chemically.
- Mulching and cover-cropping to protect the soil surface.
- Timely operations to prevent weed infestation before it becomes severe.
- Strip cultivation, where only narrow strips of land are tilled.
- Uprooting and slashing of weeds manually or mechanically.
Reasons for Minimum Tillage
- To reduce the cost of cultivation by minimizing labor and fuel use.
- To control soil erosion by maintaining soil cover.
- To preserve soil moisture by reducing evaporation.
- To prevent root exposure and damage caused by excessive tillage.
- To help reconstruct and maintain the natural soil structure.
