A farmer who applies gypsum on his farmland intends to

Gypsum (calcium sulphate, CaSO₄) is a soil amendment applied to farmland primarily to reduce soil acidity. When applied to acidic soils, the calcium in gypsum helps to displace hydrogen and aluminium ions from the soil exchange complex, raising the soil pH toward a more neutral level. This makes the soil environment more favourable for crop growth and nutrient uptake.

The other options do not accurately describe the primary purpose of gypsum application. Reducing leaching is not a recognised function of gypsum. Increasing soil acidity is the opposite of what gypsum achieves. While improved soil pH can indirectly benefit soil microorganisms, increasing microbial activity is not the direct purpose of applying gypsum.

In agricultural practice, gypsum is one of several liming materials (alongside calcium carbonate and dolomite) used to correct acidic soil conditions. The correct choice of amendment depends on the severity of acidity and the specific nutrient needs of the soil.