The soil type also determines the spread of the water flowing through the soil. On loams and clay, the water spreads out more and requires larger amounts to reach the same depth. This is an important consideration and one that is easy to overlook. Excess water on a sandy soil could leach below the area where most of the roots are found Leaching water is also likely to take some soil nutrients with it, especially nitrogen. When watering plants, you need to maximize the water that roots absorb and transpire through the leaves.
Transpiration refers to the process that plants use to cool themselves.
As water evaporates from specialized areas of the leaf called stomata, it cools the leaf, similar to the way perspiration cools humans. If plants did not have this ability the leaf temperature would soar on a sunny day, eventually shutting down its biochemical processes and leading to death. If water becomes limited due to dry soils, tomatoes, like most plants simply close the stomata and limit water loss. When plants do this they not only lessen transpiration but also prevent carbon dioxide from entering the leaf. Most people water their gardens with sprinklers.