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

Nazir Gul; Muhammad Munir Babar; Asadullah Sarki; Irfan Ahmed Shaikh; Munir Ahmed Mangrio

doi:10.22581/muet1982.1801.18

Nazir Gul Drainage and Reclamation Institute of Pakistan, Tando Jam.
Muhammad Munir Babar US-Pakistan Centres for Advanced Studies in Water, Mehran University of Engineering and Technology, Jamshoro
Asadullah Sarki Sindh Agriculture University, Tando Jam.
Irfan Ahmed Shaikh Sindh Agriculture University, Tando Jam.
Munir Ahmed Mangrio Sindh Agriculture University, Tando Jam.

DOI: https://doi.org/10.22581/muet1982.1801.18

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. T₁, T₂, and T₃ 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 T₁ treatment, followed by T₂ and then by T₃ treatment. Accordingly, the contribution of SWTs towards the CWR is 94.8, 93.2 and 42.9% of the total CWR under the T₁, T₂, and T₃ treatments, respectively. Maximum yield is attained under T₃ treatment, followed by T₂ treatment and then by T₁ treatment. Likewise, maximum water productivity is achieved under T3 treatment, followed by T2 treatment and then by T₁ treatment. The dry bulk density (ρ_d) of the soil, under T₁ and T₂ treatments, increased slightly; however, it remained unchanged under the T₃ 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_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.