(a) A farmer has a large quantity of cattle manure available on the farm. (i) State two nutrients that cattle manure provides to the soil. [2] (ii) Describe...

(a)(i) Two nutrients that cattle manure provides to the soil (any two): [2]

1. Nitrogen [1]
2. Phosphorus [1]

Other acceptable answers: potassium, calcium, magnesium, or trace elements/micronutrients.

(a)(ii) Two ways cattle manure improves the physical properties of the soil (2 marks each): [4]

1. Manure adds humus (decomposed organic matter) which binds sandy soil particles together into aggregates, improving the soil's water-holding capacity so water is retained longer in the root zone rather than draining away. [2]
2. In clay soils, humus creates air spaces between the tightly packed clay particles, improving aeration and drainage. This allows roots to penetrate more easily and prevents waterlogging. [2]

Other valid points: encourages earthworm and microbial activity, which further improves soil structure through burrowing and decomposition.

(b)(i) How to make good quality compost (any 4 steps): [4]

1. Collect crop residues and organic waste material. Chop the material into smaller pieces to speed up decomposition. [1]
2. Build the heap in alternating layers: carbon-rich material (straw, dry leaves) alternated with nitrogen-rich material (green plant matter, manure). [1]
3. Keep the heap moist but not waterlogged, and cover it to retain heat and moisture. [1]
4. Allow 2 to 4 months for full decomposition. The heap should heat up to 55 to 65 degrees Celsius, which kills weed seeds and pathogens. [1]

(b)(ii) Why the compost heap should be turned regularly: [2]

1. Turning introduces oxygen (air) into the centre of the heap. [1]
2. The aerobic bacteria responsible for efficient decomposition require oxygen. Without turning, the interior becomes anaerobic, which greatly slows decomposition and produces foul-smelling by-products such as hydrogen sulphide and ammonia. [1]

(c) A situation where inorganic fertiliser is preferred over compost: [3]

When a growing crop shows an acute nutrient deficiency during the season (e.g. yellowing maize leaves indicating nitrogen shortage), inorganic fertiliser is the better choice [1] because it dissolves quickly in soil water and nutrients are immediately available to plant roots. [1] Compost releases nutrients slowly through microbial decomposition and would not correct the deficiency fast enough to save the current crop. [1]