Chapter 5 Online quizzes

It is difficult to characterise the nature of soils in a few words. With that in mind, what are the four most important components of a typical average developed soil?

Rock, regolith, earth, and biota

Mineral matter, chemical matter, organisms, water

Rocks and minerals, groundwater, air, organisms

Water, air, organisms, mineral matter

About 95% of the world's food production comes from the soil. However, we are losing this precious resource at an alarming rate. How many km² of agricultural land are lost annually due to soil degradation?

80,000 km² per year

100,000 km² per year.

120,000 km² per year.

140,000 km² per year.

What is the most important component of an average, developed soil (as % of soil mas)?

Water

Air

Mineral matter

Organic matter

Which of the following statements about soil horizons is not correct?

Soil horizons are distinctive layers within the soil that are defined by soil colour, texture, structure, and chemistry

It refers to the first couple of centimetres down from the surface, and is often marked by a light colour because of soil organic matter contents.

Soil horizons inform soil scientists about the processes that made the soil as well as current soil functioning.

The specific combination of soil horizons makes up a soil profile

____________ is a system used to grow crops outside the soil.

Greenhouse food production

Aquaculture

Hydrophonics

Permaculture

Which of the following is not a way in which mechanized agriculture increases runoff and soil erosion?

An increase in soil compaction

An increase in surface roughness

An increase in bare soil exposed for parts of the year

All of the options given are correct

What is the correct definition of land grabbing?

The buying or leasing of large pieces of land (most often defined as areas great than 1,000 ha) by companies or governments.

An approach that does not annually till the soil, but rather to 'leave the litter in the field'.

The physical loss of soil, and is triggered by wind- and water-driven processes.

The process in which soils are anthropogenically enriched by burning plant material, food waste, and other organic detritus.

Approximately what percentage of the Earths ice-free terrestrial systems have been converted into agricultural landscapes?

20%

30%

40%

50%

Soil erosion by water can result in sheet wash, rills and gullies. What is the correct definition of a gully?

The incremental removal of fine layers (~1 mm thick) of top soil, especially soil particles that were already dislodged by raindrop impact.

Concentrated paths of runoff which are usually ~10 to ~50 cm in width and from ~1 to ~10 cm in depth.

Semi-permanent erosional features that range from ~1 to ~10 m in width and depth

None of the options given is correct

Which of the following is not a correct statement about terra preta?

In terra preta, the soils are anthropogenically enriched by burning plant material, food waste, and other organic detritus.

Terra preta is now regarded as a proven model of sustainable agriculture and soil management.

Terra preta is one approach to increasing food production in areas with poor soil fertility by remaking the soil.

In terra preta a plot of natural forest is not cut down, but farmers produce the soil in open areas in the forest

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