(a) Name four methods used for clearing land before cultivation. [4] (b) Describe three harmful effects that burning vegetation can have on the soil and env...

(a) Four methods used for clearing land before cultivation:

1. Slashing / cutting - removing vegetation with machetes, cutlasses, or mechanical slashers. [1]
2. Stumping - uprooting tree stumps and large root systems from the ground. [1]
3. Burning - setting fire to cleared vegetation debris to remove it from the field. [1]
4. Bulldozing / mechanical clearing - using heavy machinery to push over trees and scrape vegetation from the land surface. [1]

(b) Three harmful effects of burning vegetation on soil and environment:

1. Destroys organic matter in the topsoil. [1] Fire burns the humus and plant residues on and in the surface layer, reducing the soil's ability to retain moisture and supply nutrients to future crops. Organic matter is the foundation of soil fertility, and its loss takes years to rebuild. [1]
2. Kills beneficial soil organisms such as earthworms, bacteria, and fungi. [1] These organisms are essential for decomposition of dead plant material, nutrient recycling, and maintaining soil structure through their burrowing and binding activities. Without them, the soil becomes biologically inactive. [1]
3. Removes ground cover and exposes the soil surface. [1] Once the protective layer of vegetation and litter is burned away, the bare soil is directly exposed to the impact of raindrops and wind, greatly increasing the risk of erosion. Topsoil can be washed away by runoff or blown away by wind. [1]

(c) Conservation tillage is a method of land preparation that disturbs the soil as little as possible [1] and retains at least 30% of crop residues on the soil surface to protect it from erosion. [1] Examples include minimum tillage (reduced passes with equipment) and no-till farming (planting directly into undisturbed soil through the residue layer).

(d) Three advantages of conservation tillage compared with conventional tillage:

1. Reduces soil erosion by keeping crop residues on the surface, which shield the soil from the direct impact of rain and wind. [1]
2. Conserves soil moisture by reducing evaporation from the soil surface. [1] The residue mulch layer acts as insulation, keeping the soil cooler and retaining water that would otherwise be lost.
3. Lowers fuel and labour costs because fewer tillage operations are needed. [1] The farmer makes fewer passes with machinery, saving time, diesel, and wear on equipment.