Assessing the Effect of Different Water Table Depths on Water Use, Yield and Water Productivity of the Okra Crop

Abstract

An experimental study was carried out on a Lysimeter with the aim of partially meeting WRs (Water Requirements) of the Okra crop through SWT (Shallow Water Table) while maintaining the SWT at various levels below the ground surface. Under the study, CWR (Crop Water Requirement), yield, water productivity, salt accrual and contribution of SWTs towards meeting the CWR are assessed. The study was designed in accordance with the principles of CRD (Complete Randomized Design) with three treatments and four replications. The treatments; viz. T 1 , T 2 , and T 3 consisted of maintaining the WTDs (Water Table Depths) at 45, 60 and 75 cm, respectively, below the ground surface. The crop was irrigated with a good quality water having EC w = 0.50 dS m -1 and pH = 7.3. The results of the study showed that the crop consumed the maximum amount of water under T 1 treatment, followed by T 2 and then by T 3 treatment. Accordingly, the contribution of SWTs towards the CWR is 94.8, 93.2 and 42.9% of the total CWR under the T 1 , T 2 , and T 3 treatments, respectively. Maximum yield is attained under T 3 treatment, followed by T 2 treatment and then by T 1 treatment. Likewise, maximum water productivity is achieved under T 3 treatment, followed by T 2 treatment and then by T 1 treatment. The dry bulk density (ρ ρ ρ ρ ρ d ) of the soil, under T 1 and T 2 treatments, increased slightly; however, it remained unchanged under the T 3 treatment. The EC se (Electrical Conductivity) of the soil increased, whereas, the pH value of the soil decreased under all the treatments. Statistically, significant difference (p < 0.05) is observed in CWR, yield, water productivity, contribution of SWT towards crop water use, plant height and weight of the Okra pod; whereas, the difference in ρ ρ ρ ρ ρ d , EC se , pH and length of the pod is observed as not significant (p > 0.05) under the three treatments. Accordingly, to make profitable use of SWTs, improve WUE and productivity, and maintain soil fertility, the depth of SWT be controlled at 75 cm for growing of the Okra crop. Adapting to this guideline will help in availing the maximum contribution of SWTs towards meeting the CWR and achieve the larger aim of water conservation.

Water requirements of banana and papaya under different water table depths and soil types in the Lower Indus Basin of Pakistan

“…Crops grown at ≤ 1.00 WTDs do not need surface irrigation, as all of their water requirements can be met from the shallow water table. However, the water requirements of the crops cultivated at WTDs > 1.00 m are fulfilled from both sources, that is, surface irrigation and groundwater contribution (Gul et al, 2018; Kahlown et al, 2005). Hence, both facilities were arranged in this experiment.…”

“…No work could have been carried out to determine the GW contribution towards meeting banana and papaya ET at different WTDs and soil types. However, Ashraf et al (2018) and Gul et al (2018) found that the GW contribution towards meeting the ET of the major crops decreased with the increase in WTD. The regression analysis shows a strong inverse correlation between GW contribution, WTDs and soil types (Figure 9).…”

Potential Impacts of Climate Change Using Long-Term Historical Climate Data on Evapotranspiration (ET) and Groundwater Contribution to Wheat and Cotton Crop

“…Due to inappropriate drainage system in Sindh, this will raise water-table depths leading to water-logging and salinity. High water-table (≤ 1.50 m) is already prevailing in the Sindh province [25]. The situation will become worsen if the management practices shall not carry out.…”