NUMERICAL MODELING FOR SOIL WATER MOVEMENT UNDER DEFICIT IRRIGATION AND PARTIAL ROOT ZONE DRYING | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 12, Volume 36, Issue 1, January 2019, Page 195-216 PDF (905.49 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2019.94448 | ||||
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| Author | ||||
| A. A. Farag | ||||
| Lecturer at Dept. of Agric. and Bio-systems Eng., Fac. of Agric., Benha Univ., Egypt. | ||||
| Abstract | ||||
| The successful water management is considered one of the best solutions for the problem of water shortage. The first step in successful water management is to estimate the water requirements for crops accurately and monitoring the residual water content in soil during the growth season, but that cost a lot of everts and money. Others most important techniques for water saving are deficit irrigation (DI), partial root zone drying (PRD) and the integration between them. So, the aim of this study is to simulate the water flow in soil by Hydraus-1D as an easy and a cheap method. Also, studying the applied full irrigation (FI), two levels of sustainable deficit irrigation (DI) applied 75% of total crop evapotranspiration (ETc) (DI75%)and applied 50% of ETc (DI50%), partial root zone drying (PRD) and the integration between DI and PRD on eggplant yield and water productivity efficiency (WP). The experimental work was carried out during the summer seasons of 2017 and 2018 at the experimental farm of Faculty of Agriculture (Moshtohor), Benha University. The soil water content (θ) was measured several times during the growth season by using soil moisture sensor (ML3-Theta-Probe) at depths of 10, 30 and 50 cm. In addition, a numerical modeling was used for predicting the soil water content and comparing the output of model with the actual measured soil water content. The results of the numerical model showed that, the simulated and measured θ values were very close to each other. Moreover, the soil water content under subsurface drip irrigation (SSDI) at a depth of 10 cm were higher by 15.44 % than the corresponding ones under surface drip irrigation (SDI), while at depths of 30 and 50 cm, the values of θ under SDI were higher by 7.16 % and 11.41 % than the corresponding ones under SSDI, respectively. PRD technique with full irrigation (FIPRD) treatment increase the yield and WP by average values about 7.5 % and 16.25 % than that obtained without PRD, respectively under SDI and SSDI. In addition, the PRD technique associated with deficit irrigation treatments resulted in lower fluctuation in the water contents in the vertical distribution than that obtained by the corresponding treatments without PRD technique. While, the using DI decreased the yield and increase WP by different percentage. DI75% decrease the yield by average value 14.9 % than that obtained at FI and increase WP by 29.1 % under SDI and SSDI. DI50% significantly decreased the yield by average value 36.25 % and increase significantly the WP by 59.1 % than the corresponding values at FI. The statistical analysis showed that, there were no significant differences among the FIPRD, FI and DI75+PRD. The SDI resulted in increasing in yield by 4.11 % but not significant than that obtained by SSDI, and SSDI increased WP by 7.15 % than that achieved under the SDI, however the differences between these values were not significant. | ||||
| Keywords | ||||
| Hydrus-1D; sustainable deficit irrigation; soil water content; surface drip irrigation; subsurface drip irrigation and water productivity | ||||
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