Theory question 102
Farm Power(a) State two advantages and two disadvantages of using biogas as a source of farm power.
(b) Mention eight simple farm tools.
(c) List two common storage structures and two processing structures that could be found on a farmstead in West Africa.
(d) Explain the term denitrification.
(e) Describe the following components of the soil: (i) mineral matter; (ii) organic matter.
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(a) Advantages: cheap, uses animal and farm waste; reduces pollution; easy to control; can heat brooders, cook, light and dry produce; leftover slurry is manure. Disadvantages: needs technical know-how; expensive digester to build and maintain; only practical where there is plenty of dung; not widely available.
(b) Any eight: cutlass; hoe; spade; shovel; rake; sickle; secateurs; hand trowel; hand fork; garden fork; watering can; wheelbarrow; axe; mattock; pick-axe; dibber; budding knife; head pan.
(c) Storage (two): barn; crib; silo; rhumbu; warehouse; cold room; bins. Processing (two): rice mill; cassava/garri processing shed; oil mill; smoking kiln; abattoir; tobacco curing barn.
(d) Denitrification: the conversion of nitrates in the soil into nitrogen gas (or nitrous oxide) by denitrifying bacteria, especially in waterlogged, poorly aerated soil, so nitrogen is lost to the air.
(e)(i) Mineral matter: the inorganic part of soil from weathered rock (sand, silt, clay particles and mineral nutrients); forms the bulk of soil and supplies nutrients.
(ii) Organic matter: decayed and decaying remains of plants and animals (humus); dark, holds water and nutrients, improves structure and feeds microbes.
Name the bacteria's role and the waterlogging condition in (d).