During the non-growing season, water accumulates in the soil for the next season. Water management at the end of the previous growing season can affect how much room is left in the soil to store off-season precipitation. At the end of the growing season there needs to be concern for completing the current crop's water needs, but also there needs to be soil water storage available for precipitation. Excess precipitation that cannot be stored will likely dissolve left over nutrients and chemicals and leach them below the root zone where they are not available for the next crop. Capturing and utilizing rainfall during the growing season is equally as important as during the non-growing season.
Irrigation management needs to be geared to leave room in the active root zone for precipitation.
The philosophy that irrigation is supplemental to rainfall is key in reducing pollution potential. During the crop growing season, crop water needs must be balanced with soil water availability to minimize both leaching potential and crop water stress. With irrigation to supplement rainfall, water can be managed to achieve this goal. However, striking this balance is easier said than done. Crops respond to many factors as they determine their daily water requirements.