(a)(i) Advantages of manual labour: (a) it is cheap (b) maximum contact enables closer and better observation (c) allows for selective operation in any cropping system (d) lower energy expended than mechanical energy (e) intelligence enables man to control other sources of farm power (f) can be used for jobs that require precision (g) easily available. (ii) Disadvantages of manual labour: (a) can be difficult to manage (b) prone to injuries (c) limited capacity/low output/area covered is limited (d) illness may hamper work (e) efficiency decreases with age (f) hard and tiring (g) it is time consuming (h) less efficient, compared with machine.
(b) Qualities of good draught animals: (i) good body size/deep barrel (ii) strong hind limbs and a sloping rump (iii) strong hooves, good stride and stance (gait) (iv) preferably males/castrates (v) docile animals (vi) should be healthy (vii) energetic/strong/powerful
(c) Precautions: (i) treat animals fairly to prevent being angered (ii) apply muzzle (iii) do not over work them (iv) best to work early in the morning or evening (v) ensure animals are healthy; kept in healthy environment (vi) feed and provide adequate water.
(d)(i) Harnessing power in sun: (a) solar energy trapped by photo-voltaic cell (b) solar collectors/panels (c) can be converted to electrical energy (d) energy is stored in batteries (e) energy may be used directly. (ii) Harnessing power in Biogas: Animal dung is mixed with water. It is then stored in airtight device/digester/dome. Anaerobic decomposition by microbes occurs. A colourless and odourless gas (methane) produced. The gas is then stored for use in cooking.