(a) (i) Define the term soil tillage. [2 marks] (ii) Distinguish between primary tillage and secondary tillage. [2 marks] (b) Outline three roles of each of...

(a)(i) Soil tillage

Soil tillage is the mechanical manipulation or working of the soil (by ploughing, harrowing, ridging, etc.) to loosen it, prepare a good seedbed, control weeds and create favourable conditions for planting and crop growth.

(a)(ii) Primary versus secondary tillage

Primary tillage is the first, deep and rough breaking of the land (for example ploughing) that opens up and loosens the soil, whereas secondary tillage is the lighter, shallow working done after primary tillage (for example harrowing and ridging) to break clods, level the soil and prepare a fine seedbed.

(b) Roles of soil management practices

(i) Green manuring

1. Adds organic matter and improves soil structure.
2. Increases soil nitrogen and fertility (especially when legumes are used).
3. Protects the soil surface from erosion and smothers weeds.

(ii) Mulching

1. Conserves soil moisture by reducing evaporation.
2. Controls weeds and moderates soil temperature.
3. Protects the soil from erosion and adds organic matter when it decays.

(c) Six reasons for irrigation in crop production

1. To supply water to crops during the dry season or periods of drought.
2. To make crop production possible all year round.
3. To supplement rainfall where it is inadequate or unreliable.
4. To dissolve and make soil nutrients and applied fertilisers available to crops.
5. To help in land preparation and softening of hard soil (as in paddy rice).
6. To reduce the harmful effects of high soil temperature and to leach out excess salts from the soil.