Factors which should be considered when selecting a wasteland to be reclaimed for agricultural use.
- The size of the area- i.e. big enough to justify reclamation.
- Soils should be fertile to minimize the cost in improving them. (Fertilizers)
- Minimal incidence of pests and diseases/controllable.
- The climate should be suitable / favorable for the intended agricultural use.
- Availability of capital to initiate the project i.e. cost effectiveness.
- Availability of skilled manpower.
- The land should be undulating for mechanization or irrigation.
- Accessibility of the area.
LAND RECLAMATION
Land reclamation is the process of converting wasteland into farm land for growing of crops and keeping of animals while land rehabilitation is the process of restoring land to its former productive state.
Importance
Intensify food production to feed the ever-increasing population
To overcome land shortage and pressure.
Methods of Land Reclamation
Irrigation
Artificial method of supplying water to a region that does not receive adequate rainfall or to ensure continuous crop production.
Done in dry areas with low rainfall and regions experiencing dry periods to sustain the growth of crops.
Dams are used to store water.
Advantages
(a) Can be used for HEP generation
(b) For fish farming
(c) Supply water for domestic use
(d) Control floods.
Negative effects
a) Can be a cause of deaths by drowning
b) Breeding ground for mosquitoes which transmit Malaria.
c) breakage can cause destruction of life and property
Factors Determining the Amount of Water Required for Irrigation
a) Climate: Areas receiving low rainfall require more water.
b) Soils: Sandy soils require more water than clays due to low water retention ability.
c) Crop: Paddy rice requires waterlogged soils while vegetables require wet and well-drained soils.
d) Size of fields: Small plots require small amounts of water while large plots require large amount of water.
Methods of Irrigation
(a) Water lifting method
Lifting water from a source by using a bucket or watering can and pouring it on the crops.
Used widely in market gardens and on farms adjacent to the water.
(b) Flood/basin irrigation
Diverting river water into a canal then to plots where it‟s flooded.
Commonly used in irrigation schemes.
(c) Sprinkler or overhead irrigation
Taking water to the fields by pipes and applying it on crops by rotating sprinklers mounted on vertical pipes.
Used on golf courses and market gardening.
(d) Trickle irrigation
Plastic pipes with holes laid in the fields through which water trickles to the base of plant.
Popular where fruits and flowers are grown.
(e) Canal irrigation
Directing water through canal to farms.
Commonly used in areas experiencing low rainfall e.g. Yatta in Machakos
(f) Drip irrigation
Inverting bottles filled with water into the roots of a plant.
Used in low rainfall areas to grow trees, fruits and flowers.
Drainage of Swamps
Process of draining excess water from the land.
Problems of land with excess water are:
a) Is a breeding ground for disease-causing vectors.
b) Is waterlogged and unsuitable for agriculture.
c) Is prone to flooding which destroys life and property.
Processes Involved
- Digging ditches for water to ooze into and flow away by gravity
- Planting eucalyptus which takes up a lot of water e.g. at Kakuzi in Makuyu.
- Laying perforated pipes in ditches which water will seep into and flow away by gravity.
Areas in Kenya with have been reclaimed by draining are:
(a) Yala on lower courses of R.Yala
(b) Bunyala on lower courses of R.Nzoia.
The project was conceived in 1970.
Objectives of the Project of Draining Them
- Free the area of pests.
- Prepare land for settlement and agriculture.
- Ease population on Kano plains.
- Reduce flooding and associated hazards.
- Develop the otherwise remote area.
Achievements
- Flooding has been controlled.
- About 800 hectares are available for agriculture and settlement.
- Water borne diseases have been brought under control.
Control of Pests
Mosquitoes
- Fumigation
- Draining of stagnant water
- Spraying
- Clearing of bushes near settlements.
Rodents, birds, squirrels and porcupines
- trapping
- poisoning
- hunting
- Scaring away
Tsetse flies
They thrive in damp areas with high temperatures and prefer bushy vegetation as breeding grounds.
Examples of tsetse fly-infested areas are Lambwe valley in Kenya and Miombo woodland in Tanzania.
The control of tsetse fly at Miombo woodland was aimed at:
- a) Eliminating the pest to obtain land for agriculture.
- b) To treat sick people and animals to check the spread of resultant diseases.
Measures Taken
Bush Clearing
Selective clearing of bushes was applied to prevent soil degradation.
Caused tsetse fly to lack a place to breed and killed adult flies and pupae due to low humidity.
Bush Spraying
Spraying from the ground or from a low flying aircraft.
Doesn’t affect other organisms.
Disadvantages
- Some insecticides such as DDT have serious environmental effects.
- The fly develops resistance and a high dose of chemicals has to be used.
- Kills other useful organisms.
Sterilization males
Making the insect unable to reproduce by obstructing its reproductive organs.
Luring the male flies to some chemical substance which sterilises them
When they mate with the female fertilization doesn’t occur which reduces insect population.
Traps
- Square of black cloth coated with glue on which the insects stick.
- Traps impregnated with insecticides which kills the insects.
- Creation of Buffer Zones
-Belt of 5 km wide with dense cultivated vegetation to create barrier which the fly couldn’t cross.
The killing of the Hosts
Wild animals that the fly fed were selectively hunted and killed.
Methods of Land Rehabilitation
Afforestation and Reafforestation
Improve the productivity of land in the following ways:
a) Controls soil erosion by:
- Acting as wind breakers
- Leaves reduce impact of raindrops on the soil
- Roots hold/bind the soil particles together.
b) Vegetation reduces runoff and increases the rate of infiltration of rainwater ensuring there is a complete water cycle.
c) Decayed vegetation provides humus which restores soil fertility.
d) Roots help moisture to percolate deeply into the ground.
e) Modifies the climate of an area by moisture being released to the atmosphere causing higher rainfall and lowering the temperature.
Bush Fallowing
Cultivating a field for a period of 2-3 years then abandoning it for another so that it may regain fertility naturally by wild vegetation adding humus into the soil. Grass Strips and Cover Crops
Grass and cover crops e.g. sweet potato vines, beans and peas reduce the speed of running water thus helping to check soil erosion.
Mulching
Covering the soil using crop residues or artificial materials such as polythene sheets.
Helps to conserve the soil in the following ways:
- Reduces evaporation helping to conserve moisture in the soil.
- Help to check the speed of running water.
- Reduces the splashing effect of rain drops.
- Reduces runoff and increases infiltration ensuring more moisture is going to be available for plants growth.
- Mulch from crop residues decomposes releasing nutrients into the soil.
- Controls weeds
Application of Manure and Fertilizer
Replenishing nutrients depleted from the soil by constant application of manure or chemical fertilizers.
Controlled Grazing
To solve the problem of overgrazing:
- The government is advising the farmers through extension officers on the importance of matching the number of livestock with the carrying capacity of land.
- Emphasizing on quality than quantity by introducing exotic breeds and cross breeds.
- Establishing ranches in livestock farming regions e.g. Kaptuei group ranch.
- The land should be subdivided into paddocks so that different sections have time to regain pasture at different intervals.
Filling Quarries
Filling the pits with rocks and topping with fertile soils e.g. Bamburi Nature Trail where trees have been planted and animals introduced.
Drainage Trenches
Flooded areas can be rehabilitated by:
Digging trenches to drain off excess water to rehabilitate flooded areas.
Another method is to construct dams across rivers.
Planting Drought Resistant Crops
Planting in Arid and Semi-Arid Lands drought resistant and quick maturing crops which take advantage of the short wet season e.g. Pigeon peas, cassava, millet, sorghum, Katumani maize etc.
