(a)(i) of Primary Tillage Implement: These are implements used to break and turn the soil over and in so doing clods or lumps are formed e.g plough.
(ii) Secondary tillage implement: This is basically the implement used after ploughing to break down soil clods/lumps into fine tilth/ridging e.g. harrow, cultivator, ridger. OR Implements used after ploughing to pulverize soil/ridging e.g. harrow, cultivator, ridger.
(b)(i) Reasons why disc ploughs are preferred to Mouldboard ploughs for soils in West Africa:
(i) The soils often contain many obstacles such as rocks and stumps buried in the soil over which disc plough can easily roll. (ii) Soil surfaces are generally hard in West Africa, which can be more easily worked by the disc plough than the mouldboard plough. (iii) Disc plough cuts deeper than mouldboard plough. (iv) Disc plough burries weed more effectively than mouldboard plough. (v) Disc plough works better onor clay soil than mouldboard.
(ii) Major parts of a disc plough: (i) Discs. (ii) Disc standard. (iii) Beam. (iv) Furrow wheel. (v) Disc scraper. (vi) Hitch point/coupling point. (vii) Coulter.
(c) Reasons why secondary tillage is necessary before sowing of seeds:
(i) Provides fine tilth for seed germination and emergence.
(ii) Enhances good soil structure for better root development.
(iii) Improves soil aeration.
(iv) Controls weeds whose seeds become exposed on tillage thus reducing early weed competition.
(v) Improves infiltration/soil water percolation.
(d) ) Precautions to take when spraying chemicals:
(i) Do not spray rainy on a windy day.
(ii) Do not spray on a ra day.
(iii) The operator should wear protective clothings like face mask, gloves, overalls and boots when spraying.
(iv) Do not spray in the hot weather especially in the afternoon.
(v) Do not draw water from the river with chemical container.
(vi) Adhere to manufacturer's specification/instructions.
(vii) Blow blocked-nozzle with mouth when spraying.
(viii) Do not talk, smoke. drink or eat during spraying.