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SUMMARY AND RECOMMENDED
The aim of the study was to schedule irrigation depending on the active root depth, to object a good water irrigation management and to minimize water loss by deep percolation.
To achieve this aim, neutron moisture meter was used to detect soil water content after and before next irrigation, to determine soil moisture depletion, which happened during the irrigation interval and soil moisture retention curve model for different soil depths, van Genuchten model for water retention after estimating the equation parameters , m, and n. Therefore, it was possible to predict soil moisture tension at different moisture content after and before irrigation, where it was possible to determine total hydraulic potential which was equal to soil matric suction plus gravitational potential.
Total hydraulic potential through the soil profile up to active root depth it was possible to determine the loss of soil water by evaporation, water uptake by plant roots and deep percolation (under active root depth).
Three water treatments (T1, T2, and T3), (100%, 80% and 60% from the active root depth) were applied, which was estimated according to the quantity of water depleted from field capacity to a certain depth.
Chickpea plant was planted under trickle irrigation system, access tubes were installed close to the distance of 12.5cm around the dripper. These access tubes were used for neutron scattering meter.
The results can summarized in these points
- The use of neutron moisture meter was one of the simplest methods to determine soil moisture, matric potential and hydraulic potential to save time and effort.
- This technique helped to study the behavior of irrigation water in the soil profile and also helped control irrigation water.
- The highest water use efficiency was obtained by T2 followed by T1 and T3, respectively.
- Applied water values were 698.0, 495.50 and 414.0 mm for T1, T2 and T3, respectively, and the relationships were statistically significant at the level of P < 0.05, there was no significant differences between T2 and T3, There was a significant difference between T1 and T2 and between T1 and T3 for applied water.
- Increasing values of applied water increased the values of actual evapotranspiration.
- Compatibility ETc curve with ETa for treatment T2 compared with T1 and T3
- There was no difference in active root depth values between the three treatments.
- The study showed that the best depth of applied water for chickpea plant was 80% of the active root depth.
- The amount of deep percolation under the root depth were 21.02%, 9.59% and 9.37% for T1, T2 and T3, respectively.
The production of chickpeas for the three treatments (T1,T2 and T3) showed a significant variation among them where there was a significant difference between T3 and T1 by 21.39 % and between T2 and T3 by 32.39%
- The highest value of chickpea crops for T2 was 1218.09 kg / ha compared to T1 and T3 (1170.37, 919.99 kg / ha), respectively.
- FWUE results showed that there was a significant difference between T1 and T2. There was no significant difference between T2 and T3 and between T1 and T3. However, CWUE results showed no significant difference between the three treatments.
Three water treatments (100%, 80%, and 60%) of ARD were established. The results showed that 80% (T2) treatment recorded the highest results in chickpea yield (1218.09 kg/ha), crop water use efficiency (0.27 kg/m3) and water saving (28.8%) in comparison with (T1), which gave the greatest value from deep percolation (166.8 mm) that cause to increase applied water and decrease both of yield and crop water use efficiency.