What kind of soil is treated with gypsum to make it suitable for cropping? (a) Alkaline (b) Acidic (c)Water-logged (d)Soil with excessive clay content
Option A) Alkaline soils are clay soils with high pH (> 9), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate which causes the soil to swell and difficult to settle. Gypsum (calcium sulphate, CaSO4. 2H2O) can also be applied as a source of Ca++ ions to replace the sodium at the exchange complex. There must be enough natural drainage to the underground, or else an artificial subsurface drainage system must be present, to permit leaching of the excess sodium by percolation of rain and/or irrigation water through the soil profile.
