1.1 TILLAGE OBJECTIVES:
• To loosen the soil and develop a desirable soil structure for
root development
• To incorporate crop residues and improve soil texture and
fertility.
• To control weeds
• To minimize soil erosion
• To establish specific surface configuration for planting,
irrigation, drainage and harvesting operations.
• To incorporate and mix fertilizers, lime or pesticides in to
the soil.
• To break clods into small aggregates.
• To obtain seedbed compaction.
Tillage classification:
1. Primary tillage
• Initial major soil working operation designed to
reduce soil strength.
• Depth of penetration ranges from 15.2 - 90 cm
depending on the implement used.
• Implements used include, mouldboard plough,
disc plough, ripper, bedders, heavy duty disc
harrows.
Secondary tillage
• Done to break clods created during primary tillage with
the aim of:
• Reducing soil particles to a size that will allow proper
firming of the soil to establish good soil-seed contact.
• Maintaining enough soil porosity, drainage of excess
water, soil aeration, and inhibit weed growth.
• Depth of penetration ranges from 5 – 15 cm depending
in implement used.
• Implements used include cultivators, light disc harrows,
rollers and rotavators.
TYPES OF TILLAGE SYSTEMS
1. Conventional Tillage
• Many implements are used before planting
can be done.
• This may involve ripping, ploughing, discing
rolling then plant.
• The system produces the best seed bed but is
very expensive.
2. Minimum tillage
• The objective is to reduce mechanical energy
and minimize the number of trips over the
field and only perform those operations that
optimize crop growth and development.
3. Conservation tillage
• Objective is to reduce wind and soil erosion and
conserve water by encouraging water infiltration
and reducing runoff.
• A number of conservation tillage systems are
available but all aim at reducing mechanical
seedbed preparation and only seed placement
zone is tilled.
• All conservation farming systems aim not more
than 25% soil disturbance and above 30% soil
surface mulch.