MAD is best described as ...

• A. The regulation of irrigation by climate
• B. The rate at which water is applied
• C. MAD describes the allowed depletion of readily available soil moisture before irrigation
• D. The schedule that is used to avoid overwatering

Answer: (C)

MAD represents the maximum amount of soil water in the readily available portion of the root zone that a crop can use before irrigation is needed. It’s a depletion threshold used to time irrigation so the plant doesn’t experience water stress, while avoiding unnecessary watering. In practice, you relate MAD to the soil’s available water capacity and the crop’s root depth. For example, if the root zone holds about 4 inches of readily available water, and you use a MAD of 50%, you would irrigate after about 2 inches of that available water have been depleted. This concept is distinct from the rate at which water is applied or from a fixed schedule; it’s the threshold that guides when irrigation should occur. The other options describe different irrigation elements (climate regulation, application rate, or a schedule itself) but do not define this threshold of permissible depletion.