Effective management of irrigation water for maize under stressed conditions

Fresh water is becoming scarce not only in and and drought prone areas but also in regions where rainfall is abundant. Effective management of water for agricultural production in water scarcity regions therefore requires the use of innovative and sustainable approaches. The reported study was undertaken to determine an efficient strategy for management of irrigated maize under water stressed conditions, in a sub-tropical region. Field experiments were conducted on the crop over a period of 3 years with five different irrigation treatments. Layer-wise soil moisture status was continuously monitored to determine the crop water extraction pattern and hence the optimum irrigation management depth. Five irrigation treatments were maintained based on predefined levels of maximum allowable depletion (MAD) of available soil water. The treatments were 10% (T-1), 30% (T-2),45% (T-3), 60% (T-4) and 75% (T-5) maximum allowable depletion of available soil water. CERES-Maize growth simulation model was calibrated and validated for further use. The depth and time variation of soil moisture were assessed by measuring the soil moisture periodically in 15-30 cm, 30-45 cm, 45-60 cm, 60-90 cm and 90-120 cm soil profiles with a neutron probe; while the soil moisture in 0-15 cm soil profile was determined by gravimetric method. It was observed that the plants extracted most of the soil moisture from 0-45 cm soil layer. Therefore, it is recommended that only 0-45 cm soil profile be considered for scheduling of irrigation in case of maize, grown in sandy loam soil in the sub-tropical regions. Measured and simulated results revealed that under water scarcity condition, plant extractable soil water depletion of more than 45% of ASW must be avoided even during non-critical growth stages to obtain high water use efficiency and net return. The calibrated CERES-Maize Model was found to be quite efficient in simulation of yield parameters and layer-wise soil moisture extraction pattern. (C) 2004 Elsevier B.V. All rights reserved.