Estimating amount of irrigation water to apply using crop water stress index on second crop maize

Crop water stress index (CWSI) method which is one of the plant based irrigation scheduling technique, has been used to determine irrigation timing however it provides no answer to the question of ?how much water apply?. To overcome of the shortcoming of this method, an approach to find a direct relationship between the fraction of available soil water depletion (fDEP) and crop water stress index (CWSI) was investigated. In this study, three different irrigation regimes (irrigating at 40%, 60% and 80% depletion of available soil water) were considered to test the abovementioned approach on the second crop corn under the Mediterranean climatic conditions.The results revealed that using relationship developed between theoretical CWSI and fDEP, soil water depletion in the root zone depth was determined. Thus, the amount of water to apply has been determined. Therefore, CWSI technique has been improved to indicate not only irrigation time but also provides the answer ?how much water to apply?.