Q82. With reference to agricultural soils, consider the following statements:
- A high content of organic matter in soil drastically reduces its water holding capacity.
- Soil does not play any role in the sulphur cycle.
- Irrigation over a period of time can contribute to the salinization of some agricultural lands.
Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: B
- Statement 1 is not correct: Soil water holding capacity is the amount of water that a given soil can hold for crop use. Soil texture and organic matter are the key components that determine soil water-holding capacity. Organic matter influences the physical conditions of a soil in several ways. Plant residues that cover the soil surface protect the soil from sealing and crusting by raindrop impact, thereby enhancing rainwater infiltration and reducing runoff. Each 1 per cent increase in soil organic matter helps soil hold 20,000 gallons more water per acre.
- Statement 2 is not correct: Sulphur is one of three nutrients that are cycled between the soil, plant matter and the atmosphere. The sulphur cycle describes the movement of Sulphur through the atmosphere, mineral and organic forms, and through living things. Although Sulphur is primarily found in sedimentary rocks, it is particularly important to living things because it is a component of many proteins. Hence, soil plays a role in the Sulphur cycle.
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