Quiz

Soil regulation — nutrients: quick check

4 questions · Pass at 70% · +30 pts on first pass

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Question 1 · Single choice — select one

Why are nutrient cycles in natural ecosystems often described as relatively closed compared with many human-managed systems?

Because most nutrients are retained within the ecosystem through repeated recycling between organisms, organic matter, and soils. Because natural ecosystems generally contain enough nutrients from weathering processes to replace all nutrients taken up by plants. Because nutrients in natural ecosystems are mainly stored in stable mineral forms and therefore remain available over very long periods. Because nutrient losses through processes such as leaching and erosion are usually prevented by natural vegetation cover.

Question 2 · Multiple choice — select all that apply

Which processes represent a transfer of nutrients out of an agricultural production system?

Harvesting crops and transporting plant material away from the field. Incorporating crop residues into the soil after harvest. Nitrate moving below the rooting zone with infiltrating water. Nutrients entering rivers after being transported from agricultural land by run-off.

Question 3 · Single choice — select one

A farmer applies nitrogen fertiliser before a period of heavy rainfall. Which explanation best describes the potential consequence?

Increased water availability stimulates plant growth, causing plants to absorb more nitrogen than usual and preventing nutrient losses. Water movement can transport nitrate beyond the root zone before plants can take it up, reducing nutrient availability for crops and potentially affecting water quality. Heavy rainfall increases soil microbial activity, causing nitrogen to become permanently stored in organic matter. Nitrogen fertilisers mainly affect soil structure, which indirectly increases nutrient losses through erosion.

Question 4 · Multiple choice — select all that apply

Which statements correctly describe strategies for closing nutrient cycles?

Recovering phosphorus from wastewater can reduce dependence on newly mined phosphate resources. Returning composted organic material to soils can recycle nutrients while also adding organic matter. Applying larger amounts of fertiliser ensures that nutrients remain available for future crops because unused nutrients are stored in soils. Using animal manure can return nutrients from plants and animals to agricultural soils when appropriately managed.