Mention two sources of irrigation water [2marks] (b)Enumeratoin two advantages and two disadvanteges of…

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