(a) Explain what is meant by subsistence agriculture. (2 marks) (b) Discuss briefly the interdependence of agriculture and industry under the following head...

(a) Subsistence agriculture [2 marks]

Subsistence agriculture is a type of farming in which the farmer produces crops and livestock mainly to feed himself and his family, with little or nothing left over for sale.

(b) Interdependence of agriculture and industry [6 marks]

• (i) Tools, implements and machinery industries: Agriculture depends on these industries for the supply of cutlasses, hoes, ploughs, harrows and tractors used in farm operations, while the industries in turn depend on agriculture as a market for their products and for raw materials such as metals and rubber; a strong farming demand keeps such factories in business.
• (ii) Processing industries: Agriculture supplies the raw materials (cocoa, oil palm, cotton, cassava, grains) that processing industries convert into finished goods, while the processing industries provide farmers with a ready market and add value to farm produce, thereby raising farmers' income.
• (iii) Agro-chemical industries: These supply farmers with fertilizers, herbicides, insecticides and drugs that raise crop yield and protect livestock, while agriculture provides the demand that sustains the chemical industries and, in some cases, the plant raw materials they use.

(c)(i) Farm surveying [2 marks]

Farm surveying is the measurement of a piece of farmland to determine its size (area), shape, boundaries and the relative positions of features on it, and to represent them on a plan or map.

(c)(ii) The 3, 4, 5 method [6 marks]

The 3, 4, 5 method is used to set out or check a right angle (90°) at a corner of a farm. It is based on Pythagoras' theorem: a triangle whose sides are in the ratio 3 : 4 : 5 must contain a right angle between the sides 3 and 4, because

\[3^2 + 4^2 = 9 + 16 = 25 = 5^2.\]

To use it: from the corner peg (O), a distance of 3 units (e.g. 3 m) is measured along one line and a peg fixed (A); from the same corner, 4 units are measured along the second line and a peg fixed (B); the distance between A and B (the hypotenuse) is then adjusted until it is exactly 5 units. When AB = 5, the angle at O is a perfect right angle. See diagram.