Calcification in soils occurs in regions where evapotranspiration exceeds:

Calcification is a soil-forming process that occurs in regions where evapotranspiration (the total loss of water by evaporation from the soil and transpiration from plants) is greater than precipitation (rainfall and snowfall). In such dry conditions, water does not move all the way down through the soil, so calcium carbonate and other minerals are not washed out completely.

How calcification works:

• Rainwater dissolves calcium carbonate from the upper layers and carries it a short distance downward.
• Because there is not enough water to carry it out of the soil, the water evaporates or is used by plants, and the calcium carbonate is deposited in the lower part of the soil profile, usually in the B-horizon.
• Over time, this forms a layer of lime accumulation, which may harden into nodules or a hard pan.

Where calcification occurs:

• Semi-arid and sub-humid grasslands, such as the steppes of Russia and Ukraine, the Prairies of North America and the Pampas of Argentina.
• These regions have rich grassland soils such as chernozems (black earths) and Mollisols, which are among the most fertile soils in the world.
• In India, calcification is seen in the arid and semi-arid soils of Rajasthan, Haryana, Punjab and Gujarat, where the layer of lime nodules is called kankar.

Opposite processes (where precipitation exceeds evapotranspiration):

• Leaching: in humid regions, excess water moves down through the soil, washing out soluble minerals, including calcium.
• Podzolisation: in cool, humid coniferous forests, strong leaching by acidic water leaves a bleached, ash-grey upper layer.
• Laterisation: in hot, humid tropical regions with heavy seasonal rainfall, intense leaching removes silica and leaves behind insoluble oxides.

Other soil-forming processes:

Salinisation: accumulation of soluble salts near the surface in dry, poorly drained areas.

Why not the other options?

• ✗Infiltration is the entry of water into the soil, not the climatic factor compared with evapotranspiration here.
• ✗Run-off is water flowing over the land surface.
• ✗Condensation is the change of water vapour into liquid water, as in cloud formation.