What is a common use for groundwater in agriculture?

The common use for groundwater in agriculture is irrigation. Groundwater serves as a vital source for supplying water to crops, especially in areas where surface water is scarce or when rainfall is insufficient. Irrigation ensures that plants receive the necessary moisture to grow and develop throughout their growing seasons. It is particularly important in regions with dry climates or during periods of drought, as it helps to maintain crop yields and supports food production.

In terms of the other options, while they may have roles in agricultural practices, they do not primarily rely on groundwater. Pest control and fertilizer mixing can utilize various methods and sources, and machinery cooling generally involves surface water or other cooling methods rather than groundwater. Thus, irrigation stands out as the key agricultural use of groundwater.