Soil, crops and the farm as a system

What you need to know

• Soil = mineral particles + humus + water + air + living things. Loam is the farmer’s favourite mix.
• Sandy soil drains fast and is hungry. Clay holds water and is heavy. Humus is the dark, dead plant matter that feeds and binds.
• Farm tools: cutlass, hoe, rake, spade, watering can, sickle. A tool is for the hand; a machine has an engine or a complicated mechanism.
• Crops: cereals (maize, rice, millet), legumes (beans, groundnut — they fix nitrogen), roots and tubers (cassava, yam), vegetables, fruits, cash crops (cocoa, oil palm).
• Weeds compete. Pests eat. Diseases infect. Control can be cultural (rotation), mechanical, biological or chemical — chemical last, not first.
• Farm animals: cattle, sheep, goat, pig, poultry. Ruminants chew the cud. Broilers for meat, layers for eggs.