If you want to print this publication, we recommend downloading the PDF version. Summary The main purpose for irrigating is to supply needed water for crops.
Plant growth is dependent on photosynthesis.
While the plant exchanges gases with the air for photosynthesis, some water evaporates. Water is taken up from the soil by plant roots to replace this water. The water leaving the plant is called transpiration. An illustration of a water balance is shown in Figure 1 . The process of water being used by the plant and replaced by irrigation sometimes is compared to a checkbook because of the similarity to withdrawals and deposits.