1. A high content of organic matter in soil drastically reduces its water holding capacity.
2. Soil does not play any role in the sulphur cycle.
3. Irrigation over a period of time can contribute to the salinization of some agricultural lands.
Which of the statements given above is/are correct?
Correct Answer: (b) 3 only
Solution:The soil water holding capacity (SWHC) can be used to es- timate the maximum amount of water stored in the soil, and reflects the capacity of the soil to provide water for plant growth. The organic matter present in the soil makes the soil particles very dense. Due to this the water-holding capacity of the soil increases. Hence statement (1) is wrong. Sulfur is a major component of proteins, vitamins and amino acids, It is commonly found in the form of sulfate in soil and rocks. Plants take it in the form of sulphate. Sulfates continue to be obtained from the oxidation of H,S by the decomposition of dead organisms. Thus sulfur is directly in the cycle. Hence statement (2) is also wrong. Role of soil over a period of time, due to irrigation, the salt comes to the surface of the land and after evaporation of water, its residues remain on the surface. It can also collect salts in the upper layer of the soil. In this way excessive amounts of salts is formed in the soil, which is called salinization. Hence statement (3) is correct. Thus option (b) will be the correct answer.
