(a) Mention two sources of irrigation water [2marks] (b)Enumeratoin two advantages and two disadvanteges of irrigating farmlands [4marks] (c)List two ways by which the soil loses nutrients. [2marks] (d)Give two reasons for manuring in crop production [2marks] (e)State two ways by which each of the following envrionmental factors affect agricultural production: (i) temperature: (ii) soil micro-organisms; (iii) wind. [6marks]
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