In irrigation scheduling, what does Management Allowed Depletion (MAD) refer to?

• A. The portion of stored water that may be depleted before irrigation is required
• B. The maximum soil moisture level allowed before overflow
• C. The amount of water to apply in each cycle
• D. The minimum irrigation depth per zone

Answer: (A)

MAD is the amount of plant-available water in the root zone that a crop can use before irrigation is required. It represents a depletion allowance: how much stored moisture you’re willing to let disappear before you trigger watering, based on factors like crop tolerance, root depth, soil type, and climate. MAD is derived from the difference between field capacity (how much water the soil can hold after drainage) and the wilting point (when plants start to suffer water stress) and is usually expressed as a depth of water or as a percentage of available water. When the soil’s available water has been depleted by the MAD threshold, irrigation should be applied to restore the root zone toward full moisture. This differs from the total soil moisture capacity or from the actual amount applied in a cycle, and it isn’t simply the minimum irrigation depth.