S All activities that makes land suitable for planting.

Involves ploughing or digging, harrowing, ridging and rolling.

Importance of land preparation.

  1. To kill weeds.
  2. To incorporate manure and other organic matter into the soil.
  • To destroy different stages of crop pests such as eggs, larvae, pupae or adults by burying them, exposing them to heat of the sun and predators and starving them.
  1. To aerate the soil.
  2. To encourage the penetration of roots in the soil.
  3. To make subsequent operations possible. Such operations include; planting, fertilizer application, rolling and ridging.
  • To encourage water infiltration.

Operations in land preparation. A. Land clearing.

It is the removal of vegetation cover from the surface before land is tilled.

It is a method of land reclamation.

Conditions under which land clearing is necessary.

  1. When opening up a virgin land.
  2. Where a stalk growing crop was previously planted.
  • Where the interval between primary and secondary cultivation is long such that land has reverted to its original virgin state.
  1. Where land was left fallow for a long time.

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Methods of land clearing.

  1. Tree felling.

Involves cutting down of trees.  Axes, pangas and small power saws are used in small scale.  Bulldozers and root rakers are sued on large scale. Destumping/removal of stumps and disposal of trash follows.


The bush should be burned when the speed of wind is low to avoid possible spread of fire to other fields. It destroys a lot of organic matter, soil microorganisms and plant nutrients.  iii.    Slashing.

Small bushes and grasses can be cleared by this method.  A slasher or a panga is used in small scale. For large scale a mower is used. iv. Use of herbicides.

These chemicals kills weeds faster and more easily.

  1. Primary cultivation.
  • It is the initial opening of the land either after clearing the bush or following a previous crop.
  • Hand digging is done using jembe or fork jembe. In large scale, moldboard and disc plough are sued.
  • Primary cultivation is done well before the onset of rains to give time for all operations to be done in good time.

Importance of primary cultivation.

  1. To remove weeds.
  2. To bury organic matter for easy decomposition. iii. To facilitate water infiltration and aeration. iv. To destroy soil-borne pests by exposing them to predators and sun.
  3. To make planting easy.

Ways in which primary cultivation is achieved. 

  1. Hand digging.

Use of simple hand tools such as jembes, mattocks and fork-jembes to cut and turn the soil slices.

  1. Mechanical cultivation.

Use of tractor-mounted implements such as moldboard and disc ploughs. Subsoilers and rippers to break hardpans. iii. Use of ox-plough.

It is faster and more efficient than hand digging. Common where the terrain is fairly flat.

Aspects to observe in primary cultivation.

  • Time of cultivation.
    1. Land should be prepared well before the onset of rains to give weeds and other vegetation enough time to dry up and decompose.
    2. Early cultivation also allows carbon (iv) oxide and other gases to diffuse out of the soil.
    3. It also gives enough time for other subsequent operations to be done thus ensuring early planting.
  • Depth of cultivation.

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Factors determining depth of cultivation.

  1. Type of crop to be planted.

Deep-rooted crops requires a soil that has been cultivated deeply. It facilitates esay root penetration. ii.     The implements available.

Some cannot cut soil beyond a certain depth. Such implements can be sharpened or weight added on them to make them plough deeper. iii.   The type of soil.

Heavy soils are hard particularly when dry. Simple hand tools will dig shallowly on such hard soils.

3) Choice of correct implements.

Determined by:

  1. The condition of the land.
  • If land has a lot of stones and stumps, it si advisable to choose a disc plough which does not easily break on such land.
  • A jembe cannot work efficiently on a land which has a lot of couch grass as it does not pull out all the rhizomes. In such a case a fork-jembe is more efficient. The type of tilth required.

A very fine tilth requires the use of different ty.es of implements.

iii.      The depth of cultivation.

  • Heavy implements are necessary when deep cultivation is needed. Light implements are required when shallow cultivation is required.
  • Cultivate the field during the dry season when the soils are friable.
  • Very dry soils are difficult to penetrate with simple implements.
  • Very wet soils may lead to development of hardpans.
  1. Secondary cultivation/harrowing.

Operations that follows the primary cultivation.

S Seedbed refinement practices before planting.

In order to produce a fine tilt, small scale farmers’ uses simple implements such as pangas, jembes or fork-jembes and garden rakes to cut the soil clods and then pulverize the soil. Harrows such as disc, spike toothed and spring tine are used in large scale.

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Factors determining the number of times secondary cultivation is done.

  1. Size of the planting materials. Big seeds requires a fairly rough seedbed, while small ones requires a fine one.
  2. Slope of the land. On hilly land, very fine seedbed could encourage soil erosion thus reduce the number of secondary operations.
  • The moisture content of the soil. In dry soils, less operations are preferred so as to conserve the available moisture.
  1. Condition of the land after primary cultivation. Where there is plenty of trash, more secondary operations are carried out to incorporate most of the trash in the soil.

Importance of secondary cultivation.

  1. To remove any weeds that might have germinated immediately after primary cultivation.
  2. To break the soil into small pieces for easy planting. iii. To level the field in order to achieve a uniform depth of planting.
  3. To incorporate organic matter into the soil in order to encourage decomposition before planting.
  4. Tertiary operations.

S Operations carried out to suit production of certain crops.  Includes:

  1. Rolling

Process of digging soil in a continuous line and heaping it on one side to form a bund (ridge) and a furrow.


  • Encourage tuber expansion.
  • Allows easy harvesting of root crops.
  • Help to conserve soil and water in crops like sugar cane
  1. Levelling

Done to compact soil which is loose or of fine tilth.


  • Prevent small seeds from being carried away by wind.
  • Prevents soil erosion.
  • Increases seed-soil contact.

Practice of making the soil surface flat and uniform so as to promote easy germination of small seeded crops.  Facilitates uniform germination of seeds.


Process of cultivating the soil for the purpose of breaking up the hardpans. Implements used for sub-soiling includes: sub-soilers, chisel plough and cultivators.

Importance of sub-soiling.

  • Breaking hardpans.
  • Facilitates adequate gaseous exchange.
  • Bringing to the surface minerals which might have leached to the deeper layers.

Minimum tillage.

Application of a combination of framing practices aimed at least disturbance of the soil.

Farming practices involved in minimum tillage.

  • Application of herbicides in controlling weeds.
  • Use of mulch on the soil surface. Mulch prevents weeds from growing by smothering them.
  • Restricting cultivation to the area where seeds are to be planted. Weeds in the rest of the field are controlled by slashing.
  • Establishing a cover crop on the field.
  • Uprooting or slashing weeds in perennial crops.

Reasons for carrying out minimum tillage.

  1. To reduce the cost of cultivation. This is by reducing the number of operations.
  2. To control soil erosion. Mulching and cover cropping greatly reduce chances of soil erosion.
  3. To maintain soil structure. Continuous cultivation destroys soil structure hence it is avoided.
  4. To conserve moisture. Continuous cultivation exposes the soil to the heat of the sun thus enhancing evaporation of available moisture.
  5. To prevent exposure of humus to adverse conditions such as the sun’s heat that causes volatilization of nitrogen.




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