Investigating the effect of irrigation water salinity on wheat irrigation scheduling using CWSI and WDI indices (Case study of Iranshahr)

Document Type : Research Paper

Authors

1 PhD student in Irrigation and Drainage/Department of Water Engineering/ Faculty of Water and Soil/ University of Zabol/ Zabol/ Iran

2 Scientific staff in Department of Water Engineering/ Faculty of Water and Soil/ University of Zabol/ Zabol/ Iran

3 Soil and Water Research Institute/ Karaj/ Iran

10.22059/ijswr.2022.329849.669072

Abstract

The presence of salts in irrigation water and the high evapotranspiration rate in Sistan and Baluchestan cause salt accumulation in soil increasing the soil osmotic force. One method for crop irrigation planning is the use of Idso crop water stress index (CWSI) and Moran water deficit index (WDI). In order to investigate the effect of irrigation water salinity on CWSI and WDI and also wheat irrigation planning, an experiment was performed with three different irrigation water quality in Iranshahr, through the 1398-99 crop year. The experiment was performed as a randomized complete block design with 4 replications and 3 treatments including (1) irrigation water with salinity of 0.7, (2) irrigation water with salinity of 2.5 and (3) irrigation water with salinity of 5.2 dSm-1. The results showed that water with salinity of 0.7 and 2.5 dSm-1 have no significant difference in terms of yield and water use efficiency. However, the use of water with a salinity of 5.2 dSm-1 caused a significant reduction in yield and water use efficiency at a significance level of 1%. Moreover, the salinity of irrigation water increased the upper baseline in the Idso diagram and the upper side of the proposed trapezoid of Moran, but it had no effect on the baseline (plant transpiration limit under standard conditions). As a result, according to the definition of CWSI and WDI indices, these two indices decreased by 19% and 22%, respectively compared to the control treatment. The average optimal CWSI and WDI in the first treatment (non-saline) were 0.39 and 0.38, respectively, and they were 0.33 and 0.32 in the very saline treatment, respectively. This showed a decreasing trend of irrigation frequency with increasing salinity of irrigation water.

Keywords

Main Subjects

Iranian Journal of Soil and Water Research

Articles in Press, Accepted Manuscript
Available Online from 04 December 2022

Files

Share

How to cite

Statistics