Plot Type of ground cover Soil loss (tonnes per hectare per year) A Grassland 0.4 B Cereal crop 8.5 C Root crop 15.2 D Bare soil 32.6 2 Table 2.1 shows the ...

(a) The plot with the greatest soil loss is Plot D (bare soil), at 32.6 tonnes per hectare per year. [1]

(b) The most effective ground cover at reducing soil erosion is grassland (Plot A), with only 0.4 tonnes per hectare lost. [1] This is less than 2% of the loss from bare soil.

(c) Why bare soil lost much more than grassland (2 marks):

1. Grass roots bind soil particles together into stable aggregates and anchor the soil in place, making it physically harder for water to detach and carry particles away. [1]
2. The grass canopy and leaf litter absorb the impact energy of falling raindrops (raindrop splash is a major detachment mechanism on bare soil) and slow surface runoff, giving water more time to infiltrate. Bare soil has none of these protections. [1]

(d) The type of erosion most likely in dry, open areas with little vegetation is wind erosion. [1] In arid regions with sparse plant cover, strong winds pick up fine soil particles and transport them across long distances.

(e) Two ways topsoil loss reduces farmland productivity:

1. Loss of nutrients (N, P, K and micronutrients) essential for plant growth, meaning the soil can support less vigorous crops. [1]
2. Loss of organic matter reduces water-holding capacity, so less moisture is available to plants between rainfall events, and soil structure deteriorates. [1]

Other acceptable answers: thinner soil limits root growth; lower crop yields overall.

(f) How mulching protects soil from erosion:

1. Mulch covers the bare soil surface and absorbs the kinetic energy of falling raindrops, preventing the detachment of soil particles (splash erosion). [1]
2. It also slows the flow of surface water across the soil, reducing the volume and speed of runoff and allowing more water to infiltrate into the soil. [1]

(g) A farmer in a dry region should plant rows of trees as windbreaks because the trees reduce wind speed at ground level and prevent the wind from picking up and carrying away dry topsoil. [1] Windbreaks also reduce crop desiccation and evaporation from the soil surface.