Agriculture Soils

With reference to agricultural soils, consider the following statements:

  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?

  1. 1 and 2 only
  2. 3 only 
  3. 1 and 3 only 
  4. 1, 2 and 3

Answer

Plants obtain nutrients from two natural sources: organic matter and minerals. Organic matter includes any plant or animal material that returns to the soil and goes through the decomposition process. In addition to providing nutrients and habitat to organisms living in the soil, organic matter also binds soil particles into aggregates and improves the water holding capacity of soil.

The sulphur cycle is the collection of processes by which sulphur moves to and from rock, waterways and living systems. The isotopic composition of sedimentary sulphides provides primary information on the evolution of the sulphur cycle.

Too much salt can reduce crop production and water infiltration on soils that have been irrigated for 20 years or more. Too little salt can also result in a chemically compacted soil. The level of sodium (Na) in a soil can result in soil particles or even layers of differing soil profiles forming a compacted layer that the roots do not penetrate.

The correct option is B.