5 A farmer notices that one of her fields has very shallow soil with fragments of rock visible just below the surface. The field is located on a hillside wh...

(a) Two mineral particles commonly found in sandstone:

1. Quartz (silica / silicon dioxide) [1].
2. Feldspar [1].

Mica is also acceptable. Sandstone is a sedimentary rock composed primarily of sand-sized mineral grains cemented together.

(b) The soil on this hillside is shallow compared to soil on the flat land at the bottom of the hill because:

1. Soil on the hillside is continuously removed by erosion; surface runoff from rain carries soil particles downhill [1].
2. The eroded soil accumulates and is deposited at the bottom of the hill, building up a deeper soil layer there [1].
3. On a slope, there is insufficient time for deep soil to develop because material is constantly being removed faster than it can form from the underlying rock [1].

(c) The type of weathering that occurs when minerals in the rock react with acidic rainwater is chemical weathering [1]. Carbonic acid (formed when carbon dioxide dissolves in rainwater) and other acids dissolve susceptible minerals, gradually breaking down the rock structure.

(d) Two ways the farmer could improve the depth and fertility of this shallow soil over time:

1. Add organic matter such as compost or manure to increase the humus content, which improves nutrient supply and water-holding capacity [1].
2. Build terraces or contour ridges to slow erosion and allow soil to accumulate on the slope rather than being washed away [1].

Other acceptable methods: plant cover crops or grass to reduce erosion and add organic matter through root decay, and apply mulch to protect the surface and encourage earthworm activity.