Explanation:
(a)Sources of irrigation water
- Rivers
- Lakes - Streams
- Ponds -
- Bore-holes
- Wells
- Reservoirs
- Springs
- Brooks
- Dams
(b) Advantages and disadvantages of irrigating farmlands
Advantages
- Makes early planting possible
- Adds water to the soil/supply moisture to the soil for plant growth
- Helps to soften the soil for easy tillage operations
- Facilitates the survival of crops during drought
- Farmers become less dependent on rainfall
- Helps lower soil temperature
- Ensures all-year-round production
- Modifies both soil and plant environment
- Enhances microbial decomposition of organic matter in the soil
- Dissolves nutrients for root absorption
- Can be used to apply liquid fertilizers(fertigation)
Disadvantages
- High cost of irrigation equipment
- Increased salinity
- Disease transmission is possible
- Leads to build-up and spread of pests
- Vectors of diseases e.g. snails, tsetse flies, mosquitoes may breed in
irrigated areas
- Movement of farm machinery may be hindered
- May lead to leaching
- May lead to erosion/flooding
- Encourages the growth and spread of weeds
(c) Ways by which the soil loses nutrients
- Mechanical land clearing/bulldozing of virgin forests
- Crop removal/harvesting
- Continuous cropping
- Leaching
- Burning
- Overgrazing
- Erosion
- Oxidation
- reduction
- Chelation
(d) Reasons for manuring in crop production
- Improves the activities of soil organisms like earthworms
- Improves the structure of the soil
- Improves aeration within the soil
- Regulates soil temperature
- Buffering effects improve the acid-base reaction of the soil/assists in regulating soil pH
- Improves water holding capacity in sandy soil
- Improves water infiltration in clay soil
- Controls soil erosion
- Adds nutrients to the soil/improves soil fertility
- Increases cat ion exchange capacity of the soil
- Used for the control of nematodes in the soil
(e) Ways by which environmental factors affect agricultural production
(i) Temperature
- High temperature may cause heat stress/death of farm animals
- A necessary condition for germination of seeds
- Affects distribution of crops
- Affects distribution of animals
- High temperature increases evapo-transpiration
- High temperature reduces the performance of livestock/fish
- Temperature affects the ripening and maturity of fruits
- Affects microbial activities in relation to mineralization of organicsubstances
- Temperature affects productivity of human labour/draught animal
(ii) Soil micro-organisms
- Cause diseases in plants
- Bacteria in root nodules can fix nitrogen directly to plants and soils
- Reduce the quantity and quality of crops e.g. potato, yam
- Help in the decomposition of plant materials to form humus
ii)Wind
- Influences the rate of transpiration
- Causes evaporation in the soil
- May cause lodging of plants
- High wind velocity may cause soil erosion in dry/arid areas
- Important in rainfall distribution and pattern
- Important in fruits/seeds dispersal
- Assists in crop pollination
- Causes mechanical injury to crops e.g. loss of leaves, branches,
flowersand fruits
- Causes spore dispersal or spread of diseases
- Partly determines seasons