Which of the following is a major factor influencing soil formation?

Soil scientists recognise five major natural factors that control soil formation, often summarised by the acronym CLORPT: Climate, Organisms, Relief (topography), Parent material, and Time. Of the options given, climate is the only one that belongs to this group.

Climate - specifically temperature and rainfall - drives the rate of physical and chemical weathering of parent rock, the decomposition of organic matter, the leaching of minerals, and the biological activity within the soil profile. Hot, humid climates produce deep, highly weathered soils (e.g., tropical laterites), while cold or arid climates produce shallow, less developed soils.

Fertilizer application, irrigation, and crop rotation are all agricultural management practices carried out by humans after the soil has already formed. They may alter soil properties temporarily, but they are not among the natural factors that create soil in the first place.