UPSC CSE Prelims 2018
Statement 3 is correct. Prolonged irrigation, particularly in arid and semi-arid regions, can lead to the accumulation of soluble salts on or near the soil surface. This process, known as salinization, occurs as water evaporates, leaving dissolved salts behind. Salinization can degrade soil quality, reduce fertility, and negatively impact agricultural productivity.
Statement 1 is incorrect. A high content of organic matter in soil significantly enhances its water-holding capacity. Organic matter improves soil structure, increases porosity, and acts like a sponge, allowing the soil to retain more moisture for longer periods. This is particularly beneficial in sandy soils, which naturally have low water retention.
Statement 2 is incorrect. Soil plays a crucial and active role in the Sulphur cycle. It contains various forms of sulphur, including organic sulphur, which is decomposed by soil microbes, releasing inorganic sulphur compounds. Soil also stores sulphate minerals (SO₄²⁻), which are the primary form of sulphur absorbed by plants. Microbial processes within the soil facilitate the transformation of sulphur compounds, making it an essential reservoir and site of transformation in the cycle.