(a) State two advantages and two disadvantages of using biogas as a source of farm power. [ 4 marks ] (b) Mention eight simple farm tools. [ 4 marks ] (c) L...

(a) Biogas as a source of farm power

Two advantages:

1. It is a cheap, renewable source of energy made from farm/animal waste.
2. It is clean and reduces pollution, and the spent slurry is a good manure.

Two disadvantages:

1. It requires a fairly costly digester and technical know-how to set up.
2. Gas production is slow and reduced in cold weather, and the gas is flammable/explosive if mishandled.

(b) Eight simple farm tools

Cutlass (matchet), hoe, rake, spade, shovel, axe, watering can and hand trowel (also file, sickle, garden fork, head-pan).

(c) Storage and processing structures on a farmstead

Two storage structures: barn and crib (also silo).

Two processing structures: the rice/oil mill and the grinding/processing shed (also cassava processing unit, drying floor).

(d) Denitrification

Denitrification is the process by which denitrifying bacteria break down nitrates in the soil and release free nitrogen gas back into the atmosphere, thereby reducing the nitrogen (fertility) available to plants.

(e) Components of the soil

(i) Mineral matter: The inorganic part of the soil formed from weathered rock particles (sand, silt and clay). It gives the soil its texture and supplies mineral nutrients to plants.

(ii) Organic matter: The part of the soil made up of decayed and decaying plant and animal remains (humus). It improves soil structure, water and nutrient retention, and supports soil organisms.